CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Thousands, unless otherwise specified	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Total
Balance at Dec. 31, 2011	$ 997	$ 216,426	$ 721,281	$ (366,954)	$ (48,107)	$ 523,643
Balance (in shares) at Dec. 31, 2011	99,701
Increase (Decrease) in Stockholders' Equity
Net income			150,952			150,952
Recognition of equity compensation		49,937	56			49,993
Net issuance/forfeiture of nonvested shares		(43,106)		43,106
Dividends accrued, $1.45, $1.18 and $2.03 per share for the year ended 2014, 2013, and 2012 respectively			(173,866)			(173,866)
Exercise of stock options		(27)		132		105
Excess tax benefits from share-based payment arrangements		6,791				6,791
Repurchase of common stock				(48,688)		(48,688)
Other comprehensive income					1,310	1,310
Balance 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, $1.45, $1.18 and $2.03 per share for the year ended 2014, 2013, and 2012 respectively			(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 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, $1.45, $1.18 and $2.03 per share for the year ended 2014, 2013, and 2012 respectively			(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 Dec. 31, 2014	$ 997	$ 318,636	$ 1,041,909	$ (525,015)	$ (50,443)	$ 786,084
Balance (in shares) at Dec. 31, 2014	99,701