Condensed Consolidated Statement Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Cash flows from operating activities:
Net earnings	$ 28,539	$ 30,935
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	4,926	5,109
Amortization of discount or premium of investments	319	102
Share-based compensation	2,280	2,205
Excess tax benefits from share-based compensation	(286)	(679)
Provision for doubtful accounts	1,289	970
Deferred income taxes	(3,498)	(47)
Decrease (increase) in:
Accounts receivable	936	(1,681)
Prepaid expenses and other current assets	(1,055)	(687)
Other assets	150	83
(Decrease) increase in:
Accounts payable and accrued expenses	(4,488)	(143)
Income taxes payable	7,532	2,450
Deferred revenue	700	11,157
Liability for uncertain tax positions	1,536	(11,873)
Other	62	252
Net cash provided by operating activities	38,942	38,153
Cash flows from investing activities:
Purchase of certificate of deposit	(5,822)	0
Redemptions/sales of available-for-sale investments	45,164	3,600
Purchase of available-for-sale investments	(15,537)	(1,243)
Purchases of property and equipment	(1,159)	(625)
Acquisition of businesses, net of cash received	(18,843)	324
Purchases of intangible assets	(900)	(1,142)
Net cash provided by investing activities	2,903	914
Cash flows from financing activities:
Repurchases of common stock and restricted stock	(40,273)	(1,091)
Issuance of common stock under employee stock purchase plan	29	38
Exercise of stock options	2,591	2,600
Dividends paid	(9,975)	0
Excess tax benefits from share-based compensation	286	679
Net cash provided by (used in) financing activities	(47,342)	2,226
Effect of exchange rate changes on cash and cash equivalents	1,820	871
Net change in cash and cash equivalents	(3,677)	42,164
Cash and cash equivalents at beginning of period	139,359	64,752
Cash and cash equivalents at end of period	$ 135,682	$ 106,916