Segment Reporting [Abstract] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Entity by Location [Axis] Entity by Location [Axis] Location [Domain] Location [Domain] London, Bermuda and Cayman Islands London Bermuda And Cayman Islands Operations [Member] London Bermuda and Cayman Islands operations. Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Number of reportable segments Number of Reportable Segments Total revenues Revenues Debt Disclosure [Abstract] Long-Term Debt Instrument Schedule of Long-term Debt Instruments [Table Text Block] Condensed Financial Information of Parent Company Only Disclosure [Abstract] Basis of Financial Reporting Condensed Financial Information of Parent Company Only Disclosure [Text Block] Statement of Financial Position [Abstract] Statement [Table] Statement [Table] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Statement [Line Items] Statement [Line Items] Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Common stock, shares authorized (in shares) Common Stock, Shares Authorized Common stock, shares issued (in shares) Common Stock, Shares, Issued Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Treasury stock shares (in shares) Treasury Stock, Shares Tax effect of accumulated other comprehensive income Other Comprehensive Income (Loss), Tax Goodwill and Intangible Assets Disclosure [Abstract] Amortizable Intangible Assets Intangible Assets Disclosure [Text Block] Investments, Debt and Equity Securities [Abstract] Schedule of Investments in Fixed Maturity Securities Available For Sale Securities Debt Maturities Table [Table Text Block] Available For Sale Securities Debt Maturities Table [Text Block] Summary of Unrealized Loss Position Unrealized Loss Position Investments Table [Table Text Block] Unrealized Loss Position Investments Table [Text Block] Amortized Cost and Fair Value of Fixed Maturity Securities by Contractual Maturity Investments Classified by Contractual Maturity Date [Table Text Block] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Maximum Maximum [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] 5.370% senior notes, Series D, quarterly interest payments, balloon due 2015 Five Point Three Seven Zero Percent Senior Notes Due Two Thousand Fifteen [Member] Five Point Three Seven Zero Percent Senior Notes Due Two Thousand Fifteen [Member] 5.660% senior notes, Series C, semi-annual interest payments, balloon due 2016 Five Point Six Six Zero Percent Senior Notes Due Two Thousand Sixteen [Member] Five Point Six Six Zero Percent Senior Notes Due Two Thousand Sixteen [Member] 4.500% senior notes, Series E, quarterly interest payments, balloon due 2018 Four Point Five Zero Zero Percent Senior Notes Due Two Thousand Eighteen [Member] Four Point Five Zero Zero Percent Senior Notes Due Two Thousand Eighteen [Member] 4.200% senior notes, semi-annual interest payments, balloon due 2024 Four Point Two Zero Zero Percent Senior Notes Due Two Thousand Twenty Four [Member] Four Point Two Zero Zero Percent Senior Notes Due Two Thousand Twenty Four [Member] 5-year term-loan facility, periodic interest and principal payments, currently LIBOR plus 1.375%, expires May 20, 2019 Five Year Term Loan Facility Expires In Two Thousand Ninteen [Member] Five Year Term Loan Facility Expires In Two Thousand Ninteen [Member] 5-year revolving-loan facility, periodic interest payments, currently LIBOR plus 1.175%, plus commitment fees of 0.20%, expires May 20, 2019 Five Year Revolving Loan Facility Expires In Two Thousand Ninteen [Member] Five Year Revolving Loan Facility Expires In Two Thousand Ninteen [Member] Revolving credit loan, quarterly interest payments, LIBOR plus up to 1.40% and availability fee up to 0.25%, expires December 31, 2016 Revolving Credit Loan Expires In Two Thousand Sixteen [Member] Revolving Credit Loan Expires In Two Thousand Sixteen [Member] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] LIBOR London Interbank Offered Rate (LIBOR) [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Line of credit facility, expiration period Line of Credit Facility, Expiration Period Debt instrument, interest rate, stated percentage Debt Instrument, Interest Rate, Stated Percentage Line of credit facility, commitment fee percentage Line of Credit Facility, Unused Capacity, Commitment Fee Percentage Debt instrument maturity year Debt Instruments Maturity Year Debt Instruments Maturity Year Debt instrument, variable interest rate Debt Instrument, Basis Spread on Variable Rate Line of credit facility, expiration date Line of Credit Facility, Expiration Date Business Combinations [Abstract] Fair Value Of Assets And Liabilities Statement [Table] Fair Value Of Assets And Liabilities Statement [Table] Fair Value Of Assets And Liabilities Statement [Table] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Wholesale Brokerage Wholesale Brokerage [Member] Wholesale Brokerage [Member] Business Combination, Separately Recognized Transactions [Axis] Business Combination, Separately Recognized Transactions [Axis] Business Combination, Separately Recognized Transactions [Domain] Business Combination, Separately Recognized Transactions [Domain] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Liberty Insurance Brokers, Inc. and Affiliates (Liberty) Liberty Insurance Brokers, Inc. and Affiliates [Member] Liberty Insurance Brokers, Inc. and Affiliates [Member] Spain Agency, Inc. Spain Agency, Inc. [Member] Spain Agency, Inc. [Member] Bellingham Underwriters, Inc. [Member] Bellingham Underwriters, Inc. [Member] Bellingham Underwriters, Inc. [Member] Fitness Insurance, LLC [Member] Fitness Insurance, LLC [Member] Fitness Insurance, LLC [Member] Other Strategic Benefit Advisors, Inc. [Member] Strategic Benefit Advisors, Inc. [Member] Other Acquisitions [Member] Other Acquisitions [Member] Other Acquisitions [Member] Fair Value Of Assets And Liabilities Statement [Line Items] Fair Value Of Assets And Liabilities Statement [Line Items] Fair Value Of Assets And Liabilities Statement [Line Items] Effective Date of Acquisition Business Acquisition, Effective Date of Acquisition Payments to Acquire Businesses, Gross Payments to Acquire Businesses, Gross Recorded Earn-Out Payable Business Acquisitions Contingent Consideration At Fair Value Business Acquisitions Contingent Consideration At Fair Value Other current assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets Business Acquisition Purchase Price Allocation Current Assets Prepaid Expenses And Other Assets Business Acquisition Purchase Price Allocation Current Assets Prepaid Expenses And Other Assets Business Acquisition Purchase Price Allocation Current Assets Prepaid Expenses And Other Assets Fixed assets Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment Business Acquisitions Purchase Price Allocation Property Plant And Equipment Business Acquisitions Purchase Price Allocation Property Plant And Equipment Business Acquisitions Purchase Price Allocation Property Plant And Equipment Goodwill Goodwill, Fair Value Disclosure Purchased customer accounts Business Acquisitions Purchase Price Allocation Amortizable Intangible Assets Business Acquisitions Purchase Price Allocation Amortizable Intangible Assets Non-compete agreements Business Acquisitions Purchase Price Allocation Noncompete Agreements Gross Business acquisitions purchase price allocation non-compete agreements gross. Total assets acquired Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets Business Acquisitions Purchase Price Allocation Assets Acquired Business Acquisitions Purchase Price Allocation Assets Acquired Business Acquisitions Purchase Price Allocation Assets Acquired Other current liabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other Deferred Tax Liabilities, Net Deferred Tax Liabilities, Net Other liabilities Business Acquisition Purchase Price Allocation Other Liabilities Assumed Business Acquisition Purchase Price Allocation Other Liabilities Assumed Total liabilities assumed Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities Net assets acquired Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net Maximum Potential Earn- Out Payable Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High Earnings Per Share [Abstract] Net Income Per Share Earnings Per Share [Text Block] Business Combination, Separately Recognized Transactions [Table] Business Combination, Separately Recognized Transactions [Table] Retail Retail [Member] Retail [Member] National Programs National Programs [Member] National Programs [Member] National Programs Divisions [Member] National Programs Divisions [Member] National Programs Divisions [Member] Various Various [Member] Various [member] Business Combination, Separately Recognized Transactions [Line Items] Business Combination, Separately Recognized Transactions [Line Items] Cash Paid Other Payable Business Acquisition Cost Of Acquired Entity Other Payable Business Acquisition Cost Of Acquired Entity Other Payable Net Assets Acquired Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Operating Segments Operating Segments [Member] Other Segment Reconciling Items [Member] Services Services [Member] Services [Member] Investment income Investment Income, Nonoperating Amortization Amortization Depreciation Depreciation Interest expense Interest Expense Income before income taxes Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Total assets Assets Capital expenditures Payments to Acquire Property, Plant, and Equipment Income Statement [Abstract] REVENUES Revenues [Abstract] Commissions and fees Insurance Commissions and Fees Other income, net Other Income Total revenues EXPENSES Costs and Expenses [Abstract] Employee compensation and benefits Employee Compensation And Benefits The aggregate amount of expenditures for salaries, wages, profit sharing and incentive compensation, and other employee benefits, including pension and other postretirement benefit expense, but excluding share-based compensation.) Non-cash stock-based compensation Share-based Compensation Other operating expenses Other Cost and Expense, Operating Gain on disposal Gain (Loss) on Disposition of Assets Interest Change in estimated acquisition earn-out payables Change In Estimated Acquisition Earn Out Payable Change In Estimated Acquisition Earn Out Payable Total expenses Operating Expenses Income before income taxes Income taxes Income Tax Expense (Benefit) Net income Net Income (Loss) Attributable to Parent Net income per share: Basic (in dollars per share) Earnings Per Share, Basic Diluted (in dollars per share) Earnings Per Share, Diluted Dividends declared per share (in dollars per share) Common Stock, Dividends, Per Share, Declared Segment Information Schedule of Segment Reporting Information, by Segment [Table Text Block] Investments Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Statement of Cash Flows [Abstract] Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Net income Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Deferred income taxes Deferred Income Tax Expense (Benefit) Amortization of debt discount Amortization of Debt Discount (Premium) Income tax benefit from exercise of shares from the stock benefit plans Excess Tax Benefit from Share-based Compensation, Operating Activities Payments On Acquisition Earn Outs In Excess Of Original Estimated Payables Payments On Acquisition Earn Outs In Excess Of Original Estimated Payables Payments on acquisition earn-outs in excess of original estimated payables. Net gain on sales of investments, fixed assets and customer accounts Net Loss Gain On Sales Of Investments Fixed Assets And Customer Accounts Net loss (gain) on sales of investments, fixed assets and customer accounts Changes in operating assets and liabilities, net of effect from acquisitions and divestitures: Increase (Decrease) in Operating Capital [Abstract] Restricted cash and investments decrease (increase) Increase (Decrease) in Restricted Cash Premiums, commissions and fees receivable decrease (increase) Increase Decrease In Premiums Commission And Fees Receivable The net change during the reporting period in other amounts due to the reporting entity, which are not otherwise defined in the taxonomy. Reinsurance recoverables (increase) Increase (Decrease) in Reinsurance Recoverable Prepaid reinsurance premiums decrease (increase) Increase (Decrease) in Prepaid Reinsurance Premiums Other assets (increase) Increase (Decrease) in Other Operating Assets Premiums payable to insurance companies increase Increase Decrease In Premiums Payable To Insurance Companies The net change during the reporting period in the premiums payable to insurance companies. Premium deposits and credits due customers increase Increase Decrease In Premium Deposits And Credits Due Customers Decrease Increase The net change during the reporting period in the premiums deposits and credits due customers. Losses and loss adjustment reserve increase Increase Decrease For Loss And Loss Adjustment Expense Increase decrease for loss and loss adjustment expense. Unearned premiums (decrease) increase Increase (Decrease) in Unearned Premiums Accounts payable increase Increase (Decrease) in Accounts Payable Accrued expenses and other liabilities (decrease) Increase (Decrease) in Accrued Liabilities and Other Operating Liabilities Other liabilities (decrease) Increase (Decrease) in Other Operating Liabilities Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities, Continuing Operations Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Additions to fixed assets Payments for businesses acquired, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired Proceeds from sales of fixed assets and customer accounts Proceeds from Sale of Productive Assets Purchases and proceeds from sales of investments Payments to Acquire Investments Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities, Continuing Operations Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Payments on acquisition earn-outs Payments On Acquisition Earn Outs Payments on acquisition earn-outs Proceeds from Issuance of Long-term Debt Proceeds from Issuance of Long-term Debt Payments on long-term debt Repayments of Long-term Debt Income tax benefit from exercise of shares from the stock benefit plans Excess Tax Benefit from Share-based Compensation, Financing Activities Issuances of common stock for employee stock benefit plans Proceeds from Stock Options Exercised Repurchase stock benefit plan shares for employees to fund tax withholdings Repurchase Of Stock Benefit Plan Shares For Employees To Fund Tax Withholdings Repurchase of stock benefit plan shares for employees to fund tax withholdings Purchase of treasury stock Payments for Repurchase of Common Stock Prepayment of accelerated share repurchase program Payments for Repurchase of Other Equity Cash dividends paid Payments of Dividends Net cash (used) provided by financing activities Net Cash Provided by (Used in) Financing Activities, Continuing Operations Net (decrease) increase in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents at beginning of period Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents at end of period Proceeds from Lines of Credit Proceeds from Lines of Credit Minimum Minimum [Member] Trading Activity [Axis] Trading Activity [Axis] Trading Activity, by Type [Domain] Trading Activity, by Type [Domain] Master Agreement Master Agreement [Member] Master Agreement [Member] New Master Agreement New Master Agreement [Member] New Master Agreement [Member] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Line of Credit Line of Credit [Member] Term Loan Term Loan [Member] Term Loan [Member] Revolving Credit Facility Revolving Credit Facility [Member] Uncommitted Facility Uncommitted Facility [Member] Uncommitted Facility [Member] Lender Name [Axis] Lender Name [Axis] Line of Credit Facility, Lender [Domain] Line of Credit Facility, Lender [Domain] Wells Fargo Revolver Wells Fargo [Member] Wells Fargo [Member] Auction Market Preferred Securities, Stock Series [Axis] Auction Market Preferred Securities, Stock Series [Axis] Auction Market Preferred Securities, Stock Series, Title [Domain] Auction Market Preferred Securities, Stock Series, Title [Domain] Series C Series C [Member] Series C [Member] Series D Series D [Member] Series D [Member] Series E Series E [Member] Series E [Member] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Beecher Acquisition Beecher [Member] Beecher [Member] Credit Agreement Credit Agreement [Member] Credit Agreement [Member] Unsecured Senior Notes Unsecured Senior Notes [Member] Unsecured Senior Notes [Member] Unsecured senior notes outstanding Unsecured Debt Debt instrument interest rate stated percentage Current portion of senior notes Senior Notes, Current Credit facility, outstanding amount Long-term Line of Credit Number of extension periods Debt Instrument, Number of Extension Periods Debt Instrument, Number of Extension Periods Extension period Debt Instrument, Extension Period Debt Instrument, Extension Period Debt instrument, maturity date Debt Instrument, Maturity Date Revolving and term loan Debt Instrument Revolving And Term Loan Debt instrument, revolving and term loan Potential increased in line of credit facility Line of Credit Facility, Maximum Borrowing Capacity Letter of credit usage fee, minimum Letter Of Credit Usage Fee Minimum Letter Of Credit Usage Fee Minimum Letter of credit usage fee, maximum Letter Of Credit Usage Fee Maximum Letter Of Credit Usage Fee Maximum LIBOR below base rate Libor Rate Below Base Rate LIBOR Rate Below Base Rate Availability fees, minimum Fees On Loans Minimum Fees On Loans Minimum Availability fees, maximum Fees On Loans Maximum Fees On Loans Maximum Borrowings outstanding Line of Credit Facility, Remaining Borrowing Capacity Letter of credit fees Issuance period Debt Instrument, Issuance Term Debt Instrument, Issuance Term Maturity period Debt Instrument, Term Unsecured revolving credit facility Unsecured Revolving Credit Facility Unsecured Revolving Credit Facility Unsecured term loans Unsecured Long-term Debt, Noncurrent Facility fee Line of Credit Facility, Commitment Fee Percentage Proceeds from lines of credit First principal payment Debt Instrument, Periodic Payment, Principal Debt instrument, face amount Debt Instrument, Face Amount Outstanding debt balance Long-term Debt 30-day Adjusted LIBOR Rate Adjusted Libor Rate Adjusted LIBOR rate Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Purchased customer accounts Customer Relationships [Member] Non-compete agreements Noncompete Agreements [Member] Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Gross Carrying Value Finite-Lived Intangible Assets, Gross Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Net Carrying Value Intangible Assets, Net (Excluding Goodwill) Weighted Average Life (Years) Finite-Lived Intangible Asset, Useful Life Current portion of loan facility Line of Credit, Current Total current portion of long-term debt Long-term Debt, Current Maturities Total notes Senior Notes Long-term credit agreements Total long-term debt Long-term Debt, Excluding Current Maturities Current portion of long-term debt Total debt Supplemental Cash Flow Elements [Abstract] Summary of Supplemental Disclosures of Cash Flow Information and Non-Cash Financing and Investing Activities Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Subsegments [Axis] Subsegments [Axis] Subsegments [Domain] Subsegments [Domain] Subsegments Consolidation Items [Axis] Subsegments Consolidation Items [Axis] Subsegments Consolidation Items [Domain] Subsegments Consolidation Items [Domain] ASSETS Assets [Abstract] Current Assets: Assets, Current [Abstract] Cash and cash equivalents Restricted cash and investments Restricted Cash and Investments, Current Short-term investments Short-term Investments Premiums, commissions and fees receivable Premiums Commissions And Fees Receivable Insurance premiums, commissions and fees due from insured or insurance companies that are currently due, including notes receivables, accrued direct bill commissions due from carriers, guaranteed supplemental commissions and profit-sharing contingent commissions, and fees in lieu of commissions earned) Reinsurance recoverable Reinsurance Recoverables, Gross Prepaid reinsurance premiums Prepaid Reinsurance Premiums Deferred income taxes Deferred Tax Assets, Net of Valuation Allowance, Current Other current assets Other Assets, Current Total current assets Assets, Current Fixed assets, net Property, Plant and Equipment, Net Goodwill Goodwill Amortizable intangible assets, net Investments Investments Other assets Other Assets, Noncurrent Total assets LIABILITIES AND SHAREHOLDERS’ EQUITY Liabilities and Equity [Abstract] Current Liabilities: Liabilities, Current [Abstract] Premiums payable to insurance companies Premiums Payable To Insurance Companies Insurance premiums payable (net of commissions) to insurance carriers, commissions payable to agents, brokers, third parties, etc that are currently due; also includes other insurance-related liabilities such as surplus lines and other premium related taxes and fees. Losses and loss adjustment reserve Liability for Claims and Claims Adjustment Expense Unearned premiums Unearned Premiums Premium deposits and credits due customers Premium Deposits And Credits Due Customers Liability for net credit balance due customers resulting from changes, cancellation of coverage or payments collected for premiums not yet effective. Accounts payable Accounts Payable, Current Accrued expenses and other liabilities Accrued Liabilities, Current Current portion of long-term debt Total current liabilities Liabilities, Current Long-term debt Deferred income taxes, net Deferred Tax Liabilities, Net, Noncurrent Other liabilities Other Liabilities, Noncurrent Shareholders’ Equity: Stockholders' Equity Attributable to Parent [Abstract] Common stock, par value $0.10 per share; authorized 280,000 shares; issued 145,874 shares and outstanding 140,821 shares at 2015, issued 145,871 shares and outstanding 143,486 shares at 2014 Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital, Common Stock Treasury stock, at cost 5,053 and 2,385 shares at 2015 and 2014, respectively Treasury Stock, Value Retained earnings Retained Earnings (Accumulated Deficit) Accumulated other comprehensive income, net of tax effect of $15 at 2015, of $0 at 2014 Accumulated Other Comprehensive Income (Loss), Net of Tax Total shareholders’ equity Stockholders' Equity Attributable to Parent Total liabilities and shareholders’ equity Liabilities and Equity Organization, Consolidation and Presentation of Financial Statements [Abstract] Nature of Operations Nature of Operations [Text Block] Amortization expense estimated, year one (2015) Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months Amortization expense estimated, year two (2016) Finite-Lived Intangible Assets, Amortization Expense, Year Two Amortization expense estimated, year three (2017) Finite-Lived Intangible Assets, Amortization Expense, Year Three Amortization expense estimated, year four (2018) Finite-Lived Intangible Assets, Amortization Expense, Year Four Amortization expense estimated, year five (2019) Finite-Lived Intangible Assets, Amortization Expense, Year Five Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Domain] Major Types of Debt and Equity Securities [Domain] U.S. Treasury securities, obligations of U.S. Government agencies and Municipals US Treasury Securities [Member] Foreign government Foreign Government Debt Securities [Member] Corporate debt Corporate Debt Securities [Member] Short duration fixed income fund Short Duration Fixed Income Fund [Member] Short Duration Fixed Income Fund [Member] Schedule of Available-for-sale Securities [Line Items] Schedule of Available-for-sale Securities [Line Items] Cost Available-for-sale Debt Securities, Amortized Cost Basis Gross Unrealized Gains Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax Gross Unrealized Losses Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax Fair Value Available-for-sale Securities Cash paid during the period for: Interest Paid [Abstract] Interest Interest Paid Income taxes Income Taxes Paid Significant non-cash investing and financing activities Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Other payable issued for purchased customer accounts Other Payables Obligations of a business that arise from the acquisition of merchandise, materials, supplies and services used in the production and/or sale of goods and services not classified as Trade Payables. Estimated acquisition earn-out payables and related charges Recorded Earn Out Payable Recorded Earn-out Payable Notes received on the sale of fixed assets and customer accounts Notes Receivable On Sale Of Fixed Assets And Customer Accounts Notes Receivable on the Sale of Fixed Assets and Customer Accounts Changes in Carrying Value of Goodwill by Operating Segment Schedule of Goodwill [Table Text Block] Reinsurance Disclosures [Abstract] Effects of Reinsurance on Premiums Written and Earned Effects of Reinsurance [Table Text Block] Disclosure of Restrictions on Dividends, Loans and Advances Disclosure [Abstract] Dividend Restrictions [Table] Dividend Restrictions [Table] Dividend Restrictions [Table] Wright Flood Wright National Flood Insurance Company [Member] Wright National Flood Insurance Company [Member] Scenario, Forecast Scenario, Forecast [Member] Dividend Restrictions [Line Items] Dividend Restrictions [Line Items] [Line Items] for Dividend Restrictions [Table] Dividend rate as a percentage of net income Fair Value Assumptions, Expected Dividend Rate Ordinary dividends payment description Statutory Dividend Payment Restrictions Disclosure Maximum dividend payout that may be made without prior approval Statutory Accounting Practices, Statutory Amount Available for Dividend Payments without Regulatory Approval Statutory Accounting Practices [Abstract] Statutory Accounting Practices [Abstract] Statutory Accounting Practices [Table] Statutory Accounting Practices [Table] Statutory Accounting Practices [Line Items] Statutory Accounting Practices [Line Items] Statutory capital and surplus required Statutory Accounting Practices, Statutory Capital and Surplus Required Statutory capital and surplus Statutory Accounting Practices, Statutory Capital and Surplus, Balance Statutory net Income Statutory Accounting Practices, Statutory Net Income Amount Goodwill Goodwill and Intangible Assets Disclosure [Text Block] Long-Term Debt Debt Disclosure [Text Block] Amortizable Intangible Assets Schedule of Finite-Lived Intangible Assets [Table Text Block] Beginning balance Business Acquisition Earn Out Payables Business acquisition earn out payables. Additions to estimated acquisition earn-out payables Additions To Estimated Acquisition Earn Out Payables Additions to estimated acquisition earn out payables. Payments for estimated acquisition earn-out payables Payments For Estimated Acquisition Earn Out Payables Payments for estimated acquisition earn out payables. Subtotal Business Acquisition Earn Out Payable After Change In Additions And Payments Business Acquisition Earn Out Payable After Change In Additions And Payments Net change in earnings from estimated acquisition earn-out payables: Net Change in Earnings from Estimated Acquisition Earn-out Payables [Abstract] Net Change in Earnings from Estimated Acquisition Earn-out Payables [Abstract] Change in fair value on estimated acquisition earn-out payables Change In Fair Value Estimated Acquisition Earn Out Payables Change In Fair Value Estimated Acquisition Earn Out Payables. Interest expense accretion Asset Retirement Obligation, Accretion Expense Net change in earnings from estimated acquisition earn-out payables Ending balance Nature of Operations Nature Of Operation Policy [Text Block] Nature Of Operation Policy. Basis of Accounting Basis of Accounting, Policy [Policy Text Block] Recently Issued Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Number of securities in unrealized loss position Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions Proceeds from sale of investment in fixed maturity securities Proceeds from Sale and Maturity of Available-for-sale Securities Investment security maturity date, start Investment Maturity Date Range Start Investment security maturity date, End Investment Maturity Date Range End Gross realized gains and losses of securities Available-for-sale Securities, Restrictions, Additional Information Investments on deposit with the state insurance department Assets Held by Insurance Regulators Subsidiary Dividend Restrictions Dividend Payment Restrictions [Text Block] Written Premiums Written, Net [Abstract] Direct premiums Direct Premiums Written Assumed premiums Assumed Premiums Written Ceded premiums Ceded Premiums Written Net premiums Premiums Written, Net Earned Premiums Earned, Net [Abstract] Direct premiums Direct Premiums Earned Assumed premiums Assumed Premiums Earned Ceded premiums Ceded Premiums Earned Net premiums Premiums Earned, Net Fair Value, Less than 12 Months Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value Unrealized Losses, Less than 12 Months Available For Sale Securities Continuous Unrealized Loss Position Less Than 12 Months Aggregate Losses Accumulated In AOCI Amount of accumulated pre-tax unrealized loss on investments in available-for-sale securities that have been in a loss position for less than twelve months recognized in Accumulated Other Comprehensive Income (AOCI). Fair Value, 12 Months or More Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value Unrealized Losses, 12 Months or More Available For Sale Securities Continuous Unrealized Loss Position 12 Months Or Longer Aggregate Losses Accumulated In AOCI Amount of accumulated pre-tax unrealized loss on securities classified as available-for-sale that have been in a loss position for twelve months or longer recognized in Accumulated Other Comprehensive Income (AOCI). Fair Value Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value Unrealized Losses Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses Accumulated In AOCI Amount of accumulated pre-tax unrealized loss on securities classified as available-for-sale recognized in Accumulated Other Comprehensive Income (AOCI). Business Acquisition, Pro Forma Information, Nonrecurring Adjustments [Table] Business Acquisition, Pro Forma Information, Nonrecurring Adjustments [Table] Nonrecurring Adjustment [Axis] Nonrecurring Adjustment [Axis] Nonrecurring Adjustment [Domain] Nonrecurring Adjustment [Domain] Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items] Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual Business Combination Pro Forma Information Income Loss Before Income Taxes Of Acquiree Since Acquisition Date Actual Business Combination Pro Forma Information Income Loss Before Income Taxes Of Acquiree Since Acquisition Date Actual Business Combination Pro Forma Information Income Loss Before Income Taxes Of Acquiree Since Acquisition Date Actual Total revenues Business Acquisition, Pro Forma Revenue Income before income taxes Business Acquisition, Pro Forma Income (Loss) from Continuing Operations, Net of Tax Net income Business Acquisition, Pro Forma Net Income (Loss) Basic (in dollars per share) Business Acquisition, Pro Forma Income (Loss) from Continuing Operations, Net of Tax, Per Share, Basic Diluted (in dollars per share) Business Acquisition, Pro Forma Income (Loss) from Continuing Operations, Net of Tax, Per Share, Diluted Weighted Average Basic Shares Outstanding, Pro Forma Weighted Average Basic Shares Outstanding, Pro Forma Weighted average number of shares outstanding: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Pro Forma Weighted Average Shares Outstanding, Diluted Pro Forma Weighted Average Shares Outstanding, Diluted Commitments and Contingencies Disclosure [Abstract] Legal and Regulatory Proceedings Commitments and Contingencies Disclosure [Text Block] Schedule of Goodwill [Table] Schedule of Goodwill [Table] Goodwill [Line Items] Goodwill [Line Items] Goodwill [Roll Forward] Goodwill [Roll Forward] Beginning balance Goodwill of acquired businesses Goodwill, Acquired During Period Goodwill disposed of relating to sales of businesses Goodwill, Written off Related to Sale of Business Unit Ending balance Amortized Cost Available-for-sale Securities, Amortized Cost Basis [Abstract] Due in one year or less Available-for-sale Securities, Debt Maturities, Next Twelve Months, Amortized Cost Basis Due after one year through five years Available-for-sale Securities, Debt Maturities, Year Two Through Five, Amortized Cost Basis Due after five years through ten years Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Amortized Cost Basis Amortized Cost, Total Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Amortized Cost Basis Fair Value Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract] Due in one year or less Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value Due after one year through five years Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value Due after five years through ten years Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Fair Value Fair Value, Total Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value Document And Entity Information [Abstract] Document and Entity Information [Abstract] Document Type Document Type Amendment Flag Amendment Flag Amendment Description Amendment Description Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Trading Symbol Trading Symbol Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Reinsurance Premiums for Insurance Companies, by Product Segment [Table] Reinsurance Premiums for Insurance Companies, by Product Segment [Table] Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] Quota Share Agreement Quota Share Agreement Member [Member] Quota Share Agreement Member [Member] Reinsurance Policy, Type [Axis] Reinsurance Policy, Type [Axis] Reinsurance Policy [Domain] Reinsurance Policy [Domain] Homeowners Homeowners [Member] Homeowners [Member] Private Passenger Auto Liability Private Passenger Auto Liability [Member] Private Passenger Auto Liability [Member] Other Liability Other Liability [Member] Other Liability [Member] Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items] Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items] Ceded rate of premiums under insurance program Percentage of Ceded Premiums Percentage of ceded premiums. Expenses and allowance rate received in premiums Percentage of reinsurance recoverables allowance Percentage of reinsurance recoverables allowance. Premiums written net Effective cedes rate under quota share agreement Percentage of flood premiums ceded Percentage of flood premiums ceded. Commission rate, percent of ceded written premiums Reinsurance percentage of ceding commission Reinsurance percentage of ceding commission. Ceded amount Reinsurance Recoverables, Including Reinsurance Premium Paid Ceded unpaid loss Reinsurance Recoverable for Unpaid Claims and Claims Adjustments Reinsurance recoverable, incurred but not reported claims Reinsurance Recoverables, Incurred but Not Reported Claims The reinsurance recoverable Reinsurance Recoverables on Unpaid Losses, Gross Reserve for losses and loss adjustment expense Reserve For Losses And Loss Adjustment Expenses For Reinsurance Liability Reserve For Losses And Loss Adjustment Expenses For Reinsurance Liability Number of reinsurers Number of reinsurers Number of reinsurers. Equity [Abstract] Shareholders' Equity Stockholders' Equity Note Disclosure [Text Block] Purchase price allocation for current year acquisitions and adjustments made for prior year acquisitions Schedule of Business Acquisitions, by Acquisition [Table Text Block] Estimated fair values of aggregate assets and liabilities acquired Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block] Unaudited pro forma results Business Acquisition, Pro Forma Information [Table Text Block] Additions, payments, and net changes, as well as interest expense accretion on estimated acquisition earn-out payables Schedule of Business Acquisitions by Acquisition, Contingent Consideration [Table Text Block] Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Other non-current liability Other Noncurrent Liabilities [Member] Extinguishment of Debt [Axis] Extinguishment of Debt [Axis] Extinguishment of Debt, Type [Domain] Extinguishment of Debt, Type [Domain] Accounts payable Accounts Payable [Member] Business Acquisition [Line Items] Business Acquisition [Line Items] Number of acquisitions Number of Businesses Acquired Number of customer accounts acquired Business Combination, Number of Customer Accounts Acquired Business Combination, Number of Customer Accounts Acquired Aggregate purchase price of acquisitions Business Acquisitions Purchase Price Allocation Adjustment Purchase Price Business acquisitions purchase price allocation adjustment purchase price. Weighted average life (years) Acquired Finite-lived Intangible Assets, Weighted Average Useful Life Goodwill assigned Goodwill currently deductible for income tax purposes Business Acquisition, Goodwill, Expected Tax Deductible Amount Goodwill currently non-deductible for income tax purposes Business Acquisition Purchase Price Allocation Goodwill Non Deductible Amount The amount of goodwill not deductible for tax purposes. Goodwill related to the recorded earn-out payables Earn Out Payable Not Deductible Until Earned Paid Earn out payable not deductible until earned paid Total revenues related to acquisitions Income before income taxes related to acquisitions Estimated acquisition earn-out payables Reconciliation between Basic and Diluted Weighted Average Shares Outstanding Schedule of Weighted Average Number of Shares [Table Text Block] Net income attributable to unvested awarded performance stock Net Income Attributable To Unvested Awarded Performance Stock Net income attributable to unvested awarded performance stock Net income attributable to common shares Net Income (Loss) Available to Common Stockholders, Basic Weighted average number of common shares outstanding - basic (in shares) Weighted Average Number of Shares Issued, Basic Less unvested awarded performance stock included in weighted average number of common shares outstanding - basic (in shares) Incremental Common Shares Attributable to Participating Nonvested Shares with Non-forfeitable Dividend Rights Weighted average number of common shares outstanding for basic earnings per common share (in shares) Weighted Average Number of Shares Outstanding, Basic Dilutive effect of stock options (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Weighted average number of shares outstanding - diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Accelerated Share Repurchases [Table] Accelerated Share Repurchases [Table] Share Repurchase Program [Axis] Share Repurchase Program [Axis] Share Repurchase Program [Domain] Share Repurchase Program [Domain] Accelerated Share Repurchase Agreement Accelerated Share Repurchase Agreement [Member] Accelerated Share Repurchase Agreement [Member] Second Accelerated Share Repurchase Agreement Second Accelerated Share Repurchase Agreement [Member] Second Accelerated Share Repurchase Agreement [Member] Accelerated Share Repurchases [Line Items] Accelerated Share Repurchases [Line Items] Shares repurchased, authorized amount Stock Repurchase Program, Authorized Amount Shares repurchased, aggregate repurchase amount Accelerated Share Repurchases, Settlement (Payment) or Receipt Total number of shares repurchased (in shares) Treasury Stock, Shares, Acquired Shares repurchased, number of shares received initially (in shares) Fair value of common stock repurchased Supplemental Disclosures of Cash Flow Information and Non-Cash Financing and Investing Activities Cash Flow, Supplemental Disclosures [Text Block] Losses and Loss Adjustment Reserve Reinsurance Loss, Loss Adjustment Expenses [Text Block] Reinsurance Loss, Loss Adjustment Expenses [Text Block] Statutory Financial Information Statutory Financial Information [Text Block] The entire disclosure for statutory financial information. Business Combinations Business Combination Disclosure [Text Block]