Consolidated Stockholders' Equity Statements (USD $) In Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning balance at Dec. 31, 2011	$ 694,549	$ 503	$ 601,484	$ 276,363	$ (161,092)	$ (22,709)
Beginning balance, shares at Dec. 31, 2011		50,335			(4,510)
Net income	194,490			194,490
Foreign currency translation	1,053					1,053
Adjustments to pension and postretirement liability, net of $3.2, $14.0 and $3.6 million tax for the years 2012, 2013 and 2014 respectively	(8,909)					(8,909)
Net current period other comprehensive income (loss)	(7,856)
Exercise of stock options, net of tax withholding forfeitures	737		(8,694)		9,431
Exercise of stock options, net of tax withholding forfeitures, shares					243
Conversion of restricted stock units into common stock, net of tax withholding forfeitures	(2,456)		(11,103)		8,647
Conversion of restricted stock units into common stock, net of tax withholding forfeitures, shares					172
Share repurchase program	(75,000)				(75,000)
Share repurchase program, shares					(2,072)
Share-based compensation	16,493		16,493
Dividends ($0.20 per share)	(9,097)			(9,097)
Ending balance at Dec. 31, 2012	811,860	503	598,180	461,756	(218,014)	(30,565)
Ending balance, shares at Dec. 31, 2012		50,335			(6,167)
Net income	103,313			103,313
Foreign currency translation	(20,720)					(20,720)
Adjustments to pension and postretirement liability, net of $3.2, $14.0 and $3.6 million tax for the years 2012, 2013 and 2014 respectively	22,104					22,104
Net current period other comprehensive income (loss)	1,384
Exercise of stock options, net of tax withholding forfeitures	(184)		(31,003)		30,819
Exercise of stock options, net of tax withholding forfeitures, shares					879
Conversion of restricted stock units into common stock, net of tax withholding forfeitures	(2,815)		(7,012)		4,197
Conversion of restricted stock units into common stock, net of tax withholding forfeitures, shares					120
Share repurchase program	(93,750)				(93,750)
Share repurchase program, shares					(1,712)
Share-based compensation	25,588		25,588
Dividends ($0.20 per share)	(8,855)			(8,855)
Ending balance at Dec. 31, 2013	836,541	503	585,753	556,214	(276,748)	(29,181)
Ending balance, shares at Dec. 31, 2013		50,335			(6,880)
Net income	74,449			74,449
Foreign currency translation	(10,387)					(10,387)
Adjustments to pension and postretirement liability, net of $3.2, $14.0 and $3.6 million tax for the years 2012, 2013 and 2014 respectively	(6,463)					(6,463)
Net current period other comprehensive income (loss)	(16,850)
Exercise of stock options, net of tax withholding forfeitures	(9,728)		(12,123)		2,395
Exercise of stock options, net of tax withholding forfeitures, shares					194
Conversion of restricted stock units into common stock, net of tax withholding forfeitures	(1,979)		(3,958)		1,979
Conversion of restricted stock units into common stock, net of tax withholding forfeitures, shares					77
Share repurchase program	(92,197)				(92,197)
Share repurchase program, shares					(1,262)
Share-based compensation	25,717		25,717
Dividends ($0.20 per share)	(8,767)			(8,767)
Ending balance at Dec. 31, 2014	$ 807,186	$ 503	$ 595,389	$ 621,896	$ (364,571)	$ (46,031)
Ending balance, shares at Dec. 31, 2014		50,335			(7,871)