Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Operating Activities:
Net earnings	$ 116,439	$ 118,329	$ 213,486	$ 225,661
Adjustments to reconcile net earnings to net cash from operating activities:
Provision for losses on accounts receivable	562	584	1,140	861
Deferred income tax (benefit) expense	(6,115)	8,986	3,781	20,923
Excess tax benefits from stock plans	(132)	(366)	(132)	(1,846)
Stock compensation expense	12,957	11,663	23,788	21,570
Depreciation and amortization	11,642	11,420	22,971	22,949
Other	(6)	27	30	113
Changes in operating assets and liabilities:
(Increase) decrease in accounts receivable	(48,344)	63,234	64,366	16,444
Increase in accounts payable and accrued expenses	51,422	8,038	36,078	22,933
Decrease in income taxes payable, net	(34,734)	(39,000)	(23,809)	(15,868)
Decrease (increase) in other current assets	1,361	(1,187)	(694)	2,382
Net cash from operating activities	105,052	181,728	341,005	316,122
Investing Activities:
Purchase of short-term investments	(2)	(46,986)	(54)	(47,008)
Proceeds from maturities of short-term investments	0	0	17	40,296
Purchase of property and equipment	(13,279)	(12,912)	(27,314)	(22,357)
Other, net	4,416	(14)	3,892	184
Net cash from investing activities	(8,865)	(59,912)	(23,459)	(28,885)
Financing Activities:
Proceeds from issuance of common stock	48,488	25,047	90,123	60,095
Repurchases of common stock	(96,115)	(128,137)	(166,407)	(205,505)
Excess tax benefits from stock plans	132	366	132	1,846
Dividends paid	(73,000)	(68,781)	(73,000)	(68,781)
Distributions to noncontrolling interest	0	0	0	(857)
Net cash from financing activities	(120,495)	(171,505)	(149,152)	(213,202)
Effect of exchange rate changes on cash and cash equivalents	(9,345)	2,272	4,074	(15,415)
(Decrease) increase in cash and cash equivalents	(33,653)	(47,417)	172,468	58,620
Cash and cash equivalents at beginning of period	1,013,917	1,033,144	807,796	927,107
Cash and cash equivalents at end of period	980,264	985,727	980,264	985,727
Taxes Paid:
Income taxes	$ 108,369	$ 101,389	$ 146,353	$ 129,650