Condensed Consolidated Statements of Stockholders' Equity (USD $) In Thousands	Total	COMMON STOCK:	CAPITAL SURPLUS:	ACCUMULATED OTHER COMPREHENSIVE INCOME:	RETAINED EARNINGS:
Balance at beginning of period at Dec. 31, 2012		$ 139	$ 798,093	$ 43,779
Balance at beginning of period, (in shares) at Dec. 31, 2012		139,439
Net issuances of restricted stock, (in shares)		958
Repurchases of common stock, (in shares)		(2,517)
Exercises of stock options, (in shares)		974
Net issuances of restricted stock		1	(1)
Net income	118,952				118,952
Foreign currency translation adjustments, net of tax	(11,261)			(11,261)
Repurchases of common stock		(2)			(86,379)
Cash dividends			(12,256)		(32,514)
Stock-based compensation expense			17,976
Exercise of stock options		1	22,396
Tax impact of equity incentive plans			2,827
Balance at end of period at Jun. 30, 2013		139	829,035	32,518	59
Balance at end of period, (in shares) at Jun. 30, 2013		138,854
Balance at beginning of period at Dec. 31, 2013	919,643	137	868,120	38,071	13,315
Balance at beginning of period, (in shares) at Dec. 31, 2013		137,466
Net issuances of restricted stock, (in shares)		798
Repurchases of common stock, (in shares)		(1,557)
Exercises of stock options, (in shares)		394
Net issuances of restricted stock		1	(1)
Net income	136,691				136,691
Foreign currency translation adjustments, net of tax	2,286			2,286
Repurchases of common stock		(1)			(65,157)
Cash dividends					(49,413)
Stock-based compensation expense			19,149
Exercise of stock options			10,628
Tax impact of equity incentive plans			1,735
Balance at end of period at Jun. 30, 2014	$ 975,561	$ 137	$ 899,631	$ 40,357	$ 35,436
Balance at end of period, (in shares) at Jun. 30, 2014		137,101