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	$ 133,306	$ 125,096	$ 111,764
Adjustments to reconcile net income to net cash provided by operating activities:
Stock-based compensation	9,170	7,443	8,289
Excess tax benefits from the exercise of stock options	(351)	(545)	(1,121)
Gain on sale of investments	(3,745)	0	0
Deferred income taxes	(3,259)	4,688	(201)
Depreciation and amortization	55,189	28,878	17,747
Change in assets and liabilities-net of effects from acquired businesses:
Receivables-net	6,131	(36,226)	9,296
Prepaid expenses and other	(5,179)	(4,770)	4,640
Accounts payable and accrued expenses	(1,907)	39,643	997
Accrued salaries and related expenses	5,261	2,029	(20,050)
Billings in excess of revenue earned	23,846	3,381	(714)
Accrued retirement	366	1,550	6,103
Other	2,527	278	(4,503)
Net cash flow from operating activities	221,355	171,445	132,247
CASH FLOWS FROM INVESTING ACTIVITIES:
Acquisition of businesses, net of cash acquired	(109,043)	(368,853)	(13,775)
Purchases of property and equipment	(54,460)	(10,257)	(4,021)
Investment in capitalized software for internal use	(5,227)	(3,051)	(2,218)
Proceeds from sale of investments	3,255	0	0
Net cash flow from investing activities	(165,475)	(382,161)	(20,014)
CASH FLOWS FROM FINANCING ACTIVITIES:
Dividends paid	(30,846)	0	0
Proceeds from exercise of stock options	8,186	13,807	12,561
Debt issuance costs	(3,873)	(4,997)	0
Excess tax benefits from the exercise of stock options	351	545	1,121
Treasury stock acquired	(44)	0	0
Issuance of senior unsecured notes	0	200,000	0
Net repayments under the revolving credit facility	0	0	(44,100)
Net cash flow from financing activities	(26,226)	209,355	(30,418)
NET CHANGE IN CASH AND CASH EQUIVALENTS	29,654	(1,361)	81,815
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	84,829	86,190	4,375
CASH AND CASH EQUIVALENTS, END OF PERIOD	114,483	84,829	86,190
SUPPLEMENTAL CASH FLOW INFORMATION
Cash paid for interest	15,357	8,908	868
Noncash financing activities:
Employee Stock Ownership Plan Contributions	$ 4,103	$ 1,923	$ 3,937