Consolidated Statement of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income(Loss)	Total
Balance at the beginning of the period at Dec. 31, 2012	$ 997	$ 230,021	$ 698,423	$ (372,404)	$ (46,797)	$ 510,240
Balance (in shares) at Dec. 31, 2012	99,701
Increase (Decrease) in Stockholders' Equity
Net income			252,998			252,998
Recognition of equity compensation		52,992	187			53,179
Net issuance/forfeiture of nonvested shares		(28,564)		28,564
Dividends accrued, $1.18, $1.45 and $1.75 per share			(101,008)			(101,008)
Exercise of stock options		(35)		170		135
Excess tax benefits from share-based payment arrangements		12,992				12,992
Repurchase of common stock				(72,132)		(72,132)
Other comprehensive income					30,938	30,938
Balance at the end of the period at Dec. 31, 2013	$ 997	267,406	850,600	(415,802)	(15,859)	687,342
Balance (in shares) at Dec. 31, 2013	99,701
Increase (Decrease) in Stockholders' Equity
Net income			313,331			313,331
Recognition of equity compensation		53,912	232			54,144
Net issuance/forfeiture of nonvested shares		(21,817)		21,817
Dividends accrued, $1.18, $1.45 and $1.75 per share			(122,254)			(122,254)
Excess tax benefits from share-based payment arrangements		19,135				19,135
Repurchase of common stock				(131,030)		(131,030)
Other comprehensive income					(34,584)	(34,584)
Balance at the end of the period at Dec. 31, 2014	$ 997	318,636	1,041,909	(525,015)	(50,443)	786,084
Balance (in shares) at Dec. 31, 2014	99,701
Increase (Decrease) in Stockholders' Equity
Net income			245,536			245,536
Recognition of equity compensation		47,256	262			47,518
Net issuance/forfeiture of nonvested shares		(39,094)		39,094
Dividends accrued, $1.18, $1.45 and $1.75 per share			(146,099)			(146,099)
Excess tax benefits from share-based payment arrangements		4,813				4,813
Repurchase of common stock				(80,335)		(80,335)
Other comprehensive income					(11,062)	(11,062)
Balance at the end of the period at Dec. 31, 2015	$ 997	$ 331,611	$ 1,141,608	$ (566,256)	$ (61,505)	$ 846,455
Balance (in shares) at Dec. 31, 2015	99,701