Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash flows from operating activities:
Net income	$ 217,997	$ 202,691	$ 175,804
Adjustments to reconcile net income to net cash provided from operating activities:
Depreciation and amortization	25,292	21,950	16,448
Accretion of contingent consideration liabilities	1,083	967	268
Stock-based compensation expense	27,092	25,693	24,320
Deferred income taxes	8,063	24,375	7,447
Changes in assets and liabilities:
Accounts receivable	(48,993)	(16,951)	(2,049)
Prepaid expenses and other assets	(3,433)	3,882	(1,188)
Other assets	3,932	(3,601)	(1,669)
Accounts payable and accrued expenses	21,480	(38,918)	25,421
Income taxes payable	6,704	18,706	(18,884)
Long-term professional liabilities	9,843	1,915	14,060
Other liabilities	1,959	(151)	1,396
Net cash provided from operating activities	271,019	240,558	241,374
Cash flows from investing activities:
Acquisition payments, net of cash acquired	(154,885)	(338,596)	(151,321)
Purchases of investments	(42,526)	(26,478)	(19,601)
Proceeds from sales or maturities of investments	38,170	15,575	22,735
Purchases of property and equipment	(31,332)	(12,113)	(14,947)
Net cash used in investing activities	(190,573)	(361,612)	(163,134)
Cash flows from financing activities:
Borrowings on line of credit	512,500	684,000	473,500
Payments on line of credit	(630,000)	(587,500)	(563,000)
Payments for amendment of line of credit	(1,970)
Payments of contingent consideration liabilities	(6,561)	(4,405)
Payments on capital lease obligations	(463)	(262)	(316)
Excess tax benefit from exercises of stock options and vesting of restricted stock	7,031	3,043	5,774
Excess tax benefit related to resolution of income tax matters		3,394
Proceeds from issuance of common stock	31,362	22,532	17,959
Net cash (used in) provided from financing activities	(88,101)	120,802	(66,083)
Net (decrease) increase in cash and cash equivalents	(7,655)	(252)	12,157
Cash and cash equivalents at beginning of year	26,251	26,503	14,346
Cash and cash equivalents at end of year	18,596	26,251	26,503
Supplemental disclosure of cash flow information:
Interest	2,569	2,559	3,666
Income taxes	119,261	88,601	113,202
Non-cash financing activities:
Equipment financed through capital leases	$ 751		$ 145

Tax benefit related to resolution of income tax matters involving share-based compensation plans. The tax benefit results from the deduction by the entity on its tax return for an award of stock that exceeds the cumulative compensation cost for common stock or preferred stock recognized for financial reporting. Includes any resulting tax benefit that exceeds the previously recognized deferred tax asset (excess tax benefits).

No definition available.