Consolidated Statements of Shareholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, shares	62,534,636		62,534,636			63,820,126
Balance, value	$ 518,433	$ 547,680	$ 518,433	$ 547,680	$ 510,445	$ 495,064
Net income (loss)	(2,579)	(1,292)	(38,018)	(35,932)	30,032
Exercise of options and related income tax effect, value			8,368	1,266	693
Purchase of treasury stock, value			(1,135)	(631)	(360)
Issuance of restricted stock, value			0	0	0
Stock-based compensation expense			7,617	6,371	7,319
Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, shares	62,753,000	62,166,000	62,753,000	62,166,000	61,877,000	64,137,000
Balance, value	6,275	6,217	6,275	6,217	6,188	6,414
Stock Issued During Period, Shares, Other			929,000	271,000	172,000
Exercise of options and related income tax effect, value			93	27	17
Issuance of restricted stock, shares			455,000	316,000	117,000
Issuance of restricted stock, value			46	31	12
Treasury [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, shares	220,000	135,000	220,000	135,000	95,000	317,000
Balance, value	(1,895)	(1,264)	(1,895)	(1,264)	(904)	(3,030)
Purchase of treasury stock, shares			(97,000)	(85,000)	(40,000)
Purchase of treasury stock, value			(1,135)	(631)	(360)
Additional Paid In Capital [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, value	456,812	449,554	456,812	449,554	442,020	472,457
Exercise of options and related income tax effect, value			8,275	1,239	676
Issuance of restricted stock, value			(46)	(31)	(12)
Stock-based compensation expense			7,617	6,371	7,319
Retained Earnings [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, value	57,241	93,173	57,241	93,173	63,141	19,223
Net income (loss)			(38,018)	(35,932)	30,032
Stock Options [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Income tax effect from share-based compensation, net			(201)	(56)	(449)
Stock Options [Member] | Additional Paid In Capital [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Income tax effect from share-based compensation, net			(201)	(56)	(449)
Restricted Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Income tax effect from share-based compensation, net				(265)
Restricted Stock [Member] | Additional Paid In Capital [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Income tax effect from share-based compensation, net				$ (265)