Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Activities:
Net earnings	$ 432,533	$ 459,497	$ 379,460
Adjustments to reconcile net earnings to net cash from operating activities:
Provision for losses on accounts receivable	2,607	2,173	763
Deferred income tax expense (benefit)	15,835	17,999	(6,576)
Excess tax benefits from stock plans	(386)	(1,850)	(1,115)
Stock compensation expense	45,217	43,415	42,533
Depreciation and amortization	46,796	46,012	49,292
Other	(3,540)	(24)	340
Changes in operating assets and liabilities:
(Increase) decrease in accounts receivable	(102,297)	62,619	(206,887)
Increase (decrease) in accounts payable and accrued expenses	102,716	(84,164)	153,424
(Decrease) increase in income taxes payable, net	(12,370)	18,382	(12,998)
Decrease (increase) in other current assets	1,988	653	(3,270)
Net cash from operating activities	529,099	564,712	394,966
Investing Activities:
Purchase of short-term investments	(54)	(47,026)	(136,726)
Proceeds from maturities of short-term investments	17	87,320	122,726
Purchase of property and equipment	(59,316)	(44,383)	(37,472)
Escrow deposit for land acquisition	0	0	(27,101)
Other, net	6,157	(3,337)	(338)
Net cash from investing activities	(53,196)	(7,426)	(78,911)
Financing Activities:
Proceeds from issuance of common stock	185,313	130,964	69,269
Repurchases of common stock	(337,658)	(629,991)	(550,781)
Excess tax benefits from stock plans	386	1,850	1,115
Dividends paid	(145,123)	(135,673)	(124,634)
Distributions to noncontrolling interest	(1,335)	(2,122)	(503)
Net cash from financing activities	(298,417)	(634,972)	(605,534)
Effect of exchange rate changes on cash and cash equivalents	(10,847)	(41,625)	(31,066)
Increase (decrease) in cash and cash equivalents	166,639	(119,311)	(320,545)
Cash and cash equivalents at beginning of year	807,796	927,107	1,247,652
Cash and cash equivalents at end of year	974,435	807,796	927,107
Taxes Paid:
Income taxes	$ 254,312	$ 239,367	$ 254,439