Condensed Consolidated Statement of Changes in Stockholders' Equity (USD $) In Thousands, unless otherwise specified	Common Stock	Additional Paid-in Capital	Retained Earnings	Common Stock Held in Treasury	Accumulated Other Comprehensive Income	Total
Balance at Dec. 31, 2011	$ 519	$ 249,469	$ 653,344	$ (240,559)	$ 8,341	$ 671,114
Increase (Decrease) in Stockholders' Equity
Net income			(247,859)			(247,859)
Other comprehensive loss					3,533	3,533
Issuance of common stock for restricted share awards (670,933 shares), (1,029,623 shares) and (1,029,520 shares), and employee stock unit awards (71,580 shares), (0 shares) and (14,228 shares), including tax benefit shortfall and award cancellations of $4.1 million, $1.5 million and excess tax benefit of $0.6 million, respectively for year end 2012, 2013, and 2014 respectively.		(16,306)		13,722		(2,584)
Awards reclassified to liability for cash settlement (259,840 shares)		(2,838)				(2,838)
Issuance of common stock for the employee stock purchase plan (71,587 shares), (121,363 shares) and (137,782 shares), respectively for year end 2012, 2013, and 2014 respectively	1	1,130				1,131
Purchase of common stock for treasury (2,470,000 shares), (2,005,200 shares), and (2,671,637shares), respectively for year end 2012, 2013, and 2014 respectively				(23,457)		(23,457)
Shares withheld for net settlements of sharebased awards (270,467 shares), (352,051 shares), (367,367 shares), respectively for year end 2012, 2013, and 2014 respectively				(2,817)		(2,817)
Share-based compensation		13,547				13,547
Balance at Dec. 31, 2012	520	245,002	405,485	(253,111)	11,874	409,770
Increase (Decrease) in Stockholders' Equity
Net income			31,085			31,085
Other comprehensive loss					(3,338)	(3,338)
Issuance of common stock for restricted share awards (670,933 shares), (1,029,623 shares) and (1,029,520 shares), and employee stock unit awards (71,580 shares), (0 shares) and (14,228 shares), including tax benefit shortfall and award cancellations of $4.1 million, $1.5 million and excess tax benefit of $0.6 million, respectively for year end 2012, 2013, and 2014 respectively.		(19,774)		17,559		(2,215)
Issuance of common stock for the employee stock purchase plan (71,587 shares), (121,363 shares) and (137,782 shares), respectively for year end 2012, 2013, and 2014 respectively	2	933				935
Purchase of common stock for treasury (2,470,000 shares), (2,005,200 shares), and (2,671,637shares), respectively for year end 2012, 2013, and 2014 respectively				(28,169)		(28,169)
Shares withheld for net settlements of sharebased awards (270,467 shares), (352,051 shares), (367,367 shares), respectively for year end 2012, 2013, and 2014 respectively				(4,532)		(4,532)
Share-based compensation		13,896				13,896
Balance at Dec. 31, 2013	522	240,057	436,570	(268,253)	8,536	417,432
Increase (Decrease) in Stockholders' Equity
Net income			50,892			50,892
Other comprehensive loss					(14,430)	(14,430)
Issuance of common stock for restricted share awards (670,933 shares), (1,029,623 shares) and (1,029,520 shares), and employee stock unit awards (71,580 shares), (0 shares) and (14,228 shares), including tax benefit shortfall and award cancellations of $4.1 million, $1.5 million and excess tax benefit of $0.6 million, respectively for year end 2012, 2013, and 2014 respectively.		(16,244)		16,020		(224)
Issuance of common stock for the employee stock purchase plan (71,587 shares), (121,363 shares) and (137,782 shares), respectively for year end 2012, 2013, and 2014 respectively		963				963
Purchase of common stock for treasury (2,470,000 shares), (2,005,200 shares), and (2,671,637shares), respectively for year end 2012, 2013, and 2014 respectively				(48,165)		(48,165)
Shares withheld for net settlements of sharebased awards (270,467 shares), (352,051 shares), (367,367 shares), respectively for year end 2012, 2013, and 2014 respectively				(6,231)		(6,231)
Share-based compensation		15,359				15,359
Balance at Dec. 31, 2014	$ 522	$ 240,135	$ 487,462	$ (306,629)	$ (5,894)	$ 415,596