CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities:
Net income	$ 62,070	$ 56,951
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization	21,610	21,625
Depreciation	5,318	5,183
Non-cash stock-based compensation	2,772	6,357
Change in estimated acquisition earn-out payables	(821)	1,363
Deferred income taxes	9,933	6,625
Amortization of debt discount	39	39
Deferred Finance Costs, Own-share Lending Arrangement, Issuance Costs, Amortization Expense	420	390
Accretion (Amortization) of Discounts and Premiums, Investments	18	0
Income tax benefit from exercise of shares from the stock benefit plans	(1,249)	(1,783)
Payments On Acquisition Earn Outs In Excess Of Original Estimated Payables	3,550	0
Net gain on sales of investments, fixed assets and customer accounts	(1,911)	(190)
Changes in operating assets and liabilities, net of effect from acquisitions and divestitures:
Restricted cash and investments (increase)	(1,322)	(25,040)
Premiums, commissions and fees receivable decrease (increase)	5,229	(5,126)
Reinsurance recoverables (increase)	(26,161)	(64)
Prepaid reinsurance premiums decrease	29,859	29,549
Other assets (increase)	(21,247)	(7,040)
Premiums payable to insurance companies (decrease) increase	(21,139)	18,538
Premium deposits and credits due customers increase (decrease)	6,238	(2,894)
Losses and loss adjustment reserve increase	26,161	64
Unearned premiums (decrease)	(29,859)	(29,549)
Accounts payable increase	22,962	32,019
Accrued expenses and other liabilities (decrease)	(50,034)	(54,100)
Other liabilities (decrease)	(3,436)	(2,215)
Net cash provided by operating activities	31,900	50,702
Cash flows from investing activities:
Additions to fixed assets	(4,252)	(3,727)
Payments for businesses acquired, net of cash acquired	(40,603)	(36,195)
Proceeds from sales of fixed assets and customer accounts	2,467	3,712
Purchases of investments	(10,106)	(7,719)
Proceeds from Sale, Maturity and Collection of Investments	7,604	9,126
Net cash used in investing activities	(44,890)	(34,803)
Cash flows from financing activities:
Payments on acquisition earn-outs	(5,527)	(4,590)
Payments on long-term debt	(6,875)	(25,000)
Income tax benefit from exercise of shares from the stock benefit plans	1,249	1,783
Issuances of common stock for employee stock benefit plans	916	500
Repurchase Of Stock Benefit Plan Shares For Employees To Fund Tax Withholdings	1,385	2,124
Purchase of treasury stock	(11,250)	(85,000)
Prepayment of accelerated share repurchase program	11,250	(15,000)
Cash dividends paid	(16,962)	(15,785)
Net cash (used in) financing activities	(28,584)	(145,216)
Net (decrease) in cash and cash equivalents	(41,574)	(129,317)
Cash and cash equivalents at beginning of period	443,420
Cash and cash equivalents at end of period	$ 401,846	$ 340,731