CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY (USD $)	Total	Common Stock	Treasury Stock	Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings
Balance at Dec. 31, 2011	$ 2,104,768,000	$ 41,804,000	$ (3,349,000)	$ 703,475,000	$ 104,547,000	$ 1,258,291,000
Balance (in shares) at Dec. 31, 2011		418,039,000	808,000
Increase (Decrease) in Stockholders' Equity
Net income	131,730,000					131,730,000
Exercise of stock appreciation rights	(6,708,000)	44,000		(6,752,000)
Exercise of stock options and stock appreciation rights (in shares)		438,000
Stock amortization and vesting	(919,000)	238,000		(1,157,000)
Stock amortization and vesting (in shares)		2,384,000
Purchase of treasury stock	0
Purchase of treasury stock (in shares)	0
Cash dividends at $0.08, $0.06 and $0.04 per share for the year ended December 31, 2014, 2013 and 2012, respectively	(16,757,000)					(16,757,000)
Other comprehensive income (loss)	(80,667,000)				(80,667,000)
Balance at Dec. 31, 2012	2,131,447,000	42,086,000	(3,349,000)	695,566,000	23,880,000	1,373,264,000
Balance (in shares) at Dec. 31, 2012		420,861,000	808,000
Increase (Decrease) in Stockholders' Equity
Net income	279,773,000					279,773,000
Exercise of stock appreciation rights	(13,226,000)	38,000		(13,264,000)
Exercise of stock options and stock appreciation rights (in shares)		382,000
Stock amortization and vesting	9,802,000	77,000		9,725,000
Stock amortization and vesting (in shares)		772,000
Tax benefit of stock-based compensation	18,913,000			18,913,000
Purchase of treasury stock	(164,634,000)		(164,634,000)
Purchase of treasury stock (in shares)	4,800,000		4,810,000
Cash dividends at $0.08, $0.06 and $0.04 per share for the year ended December 31, 2014, 2013 and 2012, respectively	(25,232,000)					(25,232,000)
Other comprehensive income (loss)	(32,241,000)				(32,241,000)
Balance at Dec. 31, 2013	2,204,602,000	42,201,000	(167,983,000)	710,940,000	(8,361,000)	1,627,805,000
Balance (in shares) at Dec. 31, 2013		422,015,000	5,618,000
Increase (Decrease) in Stockholders' Equity
Net income	104,468,000					104,468,000
Stock amortization and vesting	958,000	91,000		867,000
Stock amortization and vesting (in shares)		900,000
Tax benefit of stock-based compensation	(1,375,000)			(1,375,000)
Purchase of treasury stock	(138,852,000)		(138,852,000)
Purchase of treasury stock (in shares)	4,300,000		4,275,000
Cash dividends at $0.08, $0.06 and $0.04 per share for the year ended December 31, 2014, 2013 and 2012, respectively	(33,278,000)					(33,278,000)
Other comprehensive income (loss)	6,210,000				6,210,000
Balance at Dec. 31, 2014	$ 2,142,733,000	$ 42,292,000	$ (306,835,000)	$ 710,432,000	$ (2,151,000)	$ 1,698,995,000
Balance (in shares) at Dec. 31, 2014		422,915,000	9,893,000