CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS’ EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Treasury Stock
Shares at beginning of period (in shares) at Dec. 31, 2013		69,480				35,751
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance for stock-based compensation and dividends, net of forfeitures (in shares)		444
Repurchases of common stock (in shares)						4,896
Shares tendered in payment of the exercise price of stock options (in shares)						4
Exercise of stock options (in shares)	105	105
Employee stock purchase plan (in shares)	(35)					(35)
Shares at end of period (in shares) at Dec. 31, 2014		70,029				40,616
Balance at beginning of period at Dec. 31, 2013		$ 695	$ 404,600	$ 317	$ 47,612	$ (295,991)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance for stock-based compensation and dividends, net of forfeitures		4	369
Exercise of stock options		1	1,213
Income tax benefit from stock-based compensation			595
Stock-based compensation expense			5,475
Repurchases of common stock						(103,195)
Shares tendered in payment of the exercise price of stock options						(84)
Employee stock purchase plan	$ 699		390			309
Defined benefit pension and post-retirement plans, net of tax of $89, $429 and $394, respectively	(688)			(688)
Net income	$ 90,915				90,915
Dividends, net of forfeitures ($0.48, $0.45 and $0.41 per share, respectively)					(13,149)
Balance at end of period at Dec. 31, 2014		$ 700	412,642	(371)	125,378	$ (398,961)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance for stock-based compensation and dividends, net of forfeitures (in shares)		497
Repurchases of common stock (in shares)						1,540
Shares tendered in payment of the exercise price of stock options (in shares)						0
Exercise of stock options (in shares)	32	32
Employee stock purchase plan (in shares)	(26)					(26)
Shares at end of period (in shares) at Dec. 31, 2015		70,558				42,130
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance for stock-based compensation and dividends, net of forfeitures		$ 5	556
Exercise of stock options		0	381
Income tax benefit from stock-based compensation			551
Stock-based compensation expense			5,819
Repurchases of common stock						$ (38,058)
Shares tendered in payment of the exercise price of stock options						0
Employee stock purchase plan	$ 578		327			251
Defined benefit pension and post-retirement plans, net of tax of $89, $429 and $394, respectively	689			689
Net income	42,824				42,824
Dividends, net of forfeitures ($0.48, $0.45 and $0.41 per share, respectively)					(13,106)
Balance at end of period at Dec. 31, 2015	$ 139,627	$ 705	420,276	318	155,096	$ (436,768)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance for stock-based compensation and dividends, net of forfeitures (in shares)		695
Repurchases of common stock (in shares)						2,370
Shares tendered in payment of the exercise price of stock options (in shares)						3
Exercise of stock options (in shares)	15	15
Employee stock purchase plan (in shares)	(34)					(34)
Shares at end of period (in shares) at Dec. 31, 2016		71,268				44,469
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance for stock-based compensation and dividends, net of forfeitures		$ 8	447
Exercise of stock options		0	172
Income tax benefit from stock-based compensation			307
Stock-based compensation expense			6,705
Repurchases of common stock						$ (45,873)
Shares tendered in payment of the exercise price of stock options						(63)
Employee stock purchase plan	$ 669		305			364
Defined benefit pension and post-retirement plans, net of tax of $89, $429 and $394, respectively	(134)			(134)
Net income	32,773				32,773
Dividends, net of forfeitures ($0.48, $0.45 and $0.41 per share, respectively)					(12,902)
Balance at end of period at Dec. 31, 2016	$ 121,736	$ 713	$ 428,212	$ 184	$ 174,967	$ (482,340)