Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Operating Activities:
Net earnings	$ 97,047	$ 107,332
Adjustments to reconcile net earnings to net cash from operating activities:
Provision for losses on accounts receivable	578	277
Deferred income tax expense	9,896	11,937
Excess tax benefits from stock plans	0	(1,480)
Stock compensation expense	10,831	9,907
Depreciation and amortization	11,329	11,529
Other	36	86
Changes in operating assets and liabilities:
Decrease (increase) in accounts receivable	112,710	(46,790)
(Decrease) increase in accounts payable and accrued expenses	(15,344)	14,895
Increase in income taxes payable, net	10,925	23,132
(Increase) decrease in other current assets	(2,055)	3,569
Net cash from operating activities	235,953	134,394
Investing Activities:
Purchase of short-term investments	(52)	(22)
Proceeds from maturities of short-term investments	17	40,296
Purchase of property and equipment	(14,035)	(9,445)
Other, net	(524)	198
Net cash from investing activities	(14,594)	31,027
Financing Activities:
Proceeds from issuance of common stock	41,635	35,048
Repurchases of common stock	(70,292)	(77,368)
Excess tax benefits from stock plans	0	1,480
Distributions to noncontrolling interest	0	(857)
Net cash from financing activities	(28,657)	(41,697)
Effect of exchange rate changes on cash and cash equivalents	13,419	(17,687)
Increase in cash and cash equivalents	206,121	106,037
Cash and cash equivalents at beginning of period	807,796	927,107
Cash and cash equivalents at end of period	1,013,917	1,033,144
Taxes Paid:
Income taxes	$ 37,984	$ 28,261