Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	COMMON STOCK	CAPITAL SURPLUS	ACCUMULATED OTHER COMPREHENSIVE INCOME	RETAINED EARNINGS
Balance at beginning of period, (in shares) at Dec. 31, 2012		139,439
Balance at beginning of period at Dec. 31, 2012		$ 139	$ 798,093	$ 43,779	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net issuances of restricted stock, (in shares)		1,091
Net issuances of restricted stock		$ 1	(1)
Repurchases of common stock, (in shares)		(4,461)
Repurchases of common stock		$ (4)			(162,029)
Exercises of stock options, (in shares)	1,397	1,397
Exercises of stock options		$ 1	33,285
Cash dividends			(12,256)		(76,851)
Stock-based compensation expense			38,867
Tax impact of equity incentive plans			10,132
Foreign currency translation adjustments, net of tax	$ (5,708)			(5,708)
Net income	$ 252,195				252,195
Balance at end of period, (in shares) at Dec. 31, 2013		137,466
Balance at end of period at Dec. 31, 2013		$ 137	868,120	38,071	13,315
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net issuances of restricted stock, (in shares)		938
Net issuances of restricted stock		$ 1	(1)
Repurchases of common stock, (in shares)		(3,798)
Repurchases of common stock		$ (4)			(183,969)
Exercises of stock options, (in shares)	528	528
Exercises of stock options		$ 1	14,323
Cash dividends			0		(98,438)
Stock-based compensation expense			40,821
Tax impact of equity incentive plans			4,894
Foreign currency translation adjustments, net of tax	$ (23,341)			(23,341)
Net income	305,928				305,928
Balance at end of period, (in shares) at Dec. 31, 2014		135,134
Balance at end of period at Dec. 31, 2014	$ 979,858	$ 135	928,157	14,730	36,836
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net issuances of restricted stock, (in shares)		785
Net issuances of restricted stock		$ 1	(1)
Repurchases of common stock, (in shares)		(4,817)
Repurchases of common stock		$ (5)			(252,916)
Exercises of stock options, (in shares)	54	54
Exercises of stock options		$ 0	1,529
Cash dividends			0		(107,249)
Stock-based compensation expense			41,292
Tax impact of equity incentive plans			8,500
Foreign currency translation adjustments, net of tax	$ (25,024)			(25,024)
Net income	357,796				357,796
Balance at end of period, (in shares) at Dec. 31, 2015		131,156
Balance at end of period at Dec. 31, 2015	$ 1,003,781	$ 131	$ 979,477	$ (10,294)	$ 34,467