Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Operating Activities:
Net earnings	$ 80,610	$ 76,722
Adjustments to reconcile net earnings to net cash from operating activities:
Provision for losses (recoveries) on accounts receivable	941	(467)
Deferred income tax expense	7,122	5,481
Excess tax benefits from stock plans	(1,099)	(3,426)
Stock compensation expense	11,005	10,600
Depreciation and amortization	11,278	9,545
Other	208	217
Changes in operating assets and liabilities:
Decrease in accounts receivable	38,856	12,968
(Increase) decrease in other current assets	(485)	1,924
(Decrease) increase in accounts payable and accrued expenses	(1,390)	13,559
Increase in income taxes payable, net	18,218	20,274
Net cash from operating activities	165,264	147,397
Investing Activities:
Decrease (increase) in short-term investments, net	38	(15,780)
Purchase of property and equipment	(10,068)	(17,088)
Other, net	(444)	470
Net cash from investing activities	(10,474)	(32,398)
Financing Activities:
Proceeds from issuance of common stock	10,929	12,920
Repurchases of common stock	(17,681)	(21,865)
Excess tax benefits from stock plans	1,099	3,426
Purchase of noncontrolling interest	(7,730)	0
Net cash from financing activities	(13,383)	(5,519)
Effect of exchange rate changes on cash and cash equivalents	(7,562)	9,079
Increase in cash and cash equivalents	133,845	118,559
Cash and cash equivalents at beginning of period	1,260,842	1,294,356
Cash and cash equivalents at end of period	1,394,687	1,412,915
Taxes Paid:
Income taxes	$ 26,951	$ 26,512