Condensed Consolidated Statements of Stockholders' Equity (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Beginning Balance	$ 794,378	$ 1,065,350	$ 1,052,783	$ 1,011,351
Stock issued for benefit plans	1,909	1,622	1,654
Stock options exercised		4	636
Purchase of treasury shares	(1,065)	(1,513)	(2,805)
Tax benefits from stock-based compensation		(1,607)	175
Employee stock purchase plan	824	946	1,076
Issuance of restricted stock	0	0	0
Amortization of share-based compensation	10,787	15,557	18,995
Net Income (Loss)	(283,427)	(2,442)	21,701
Common Stock
Beginning Balance	444	439	435	430
Stock issued for benefit plans	0	0	0
Stock options exercised		0	1
Purchase of treasury shares	0	0	0
Tax benefits from stock-based compensation		0	0
Employee stock purchase plan	1	1	0
Issuance of restricted stock	4	3	4
Amortization of share-based compensation	0	0	0
Net Income (Loss)	0	0	0
Additional Paid-in Capital
Beginning Balance	771,972	762,242	748,517	727,286
Stock issued for benefit plans	(1,876)	(1,171)	354
Stock options exercised		4	635
Purchase of treasury shares	0	0	0
Tax benefits from stock-based compensation		(1,607)	175
Employee stock purchase plan	823	945	1,076
Issuance of restricted stock	(4)	(3)	(4)
Amortization of share-based compensation	10,787	15,557	18,995
Net Income (Loss)	0	0	0
Treasury Stock
Beginning Balance	(9,855)	(12,575)	(13,855)	(12,350)
Stock issued for benefit plans	3,785	2,793	1,300
Stock options exercised		0	0
Purchase of treasury shares	(1,065)	(1,513)	(2,805)
Tax benefits from stock-based compensation		0	0
Employee stock purchase plan	0	0	0
Issuance of restricted stock	0	0	0
Amortization of share-based compensation	0	0	0
Net Income (Loss)	0	0	0
Retained Earnings
Beginning Balance	31,817	315,244	317,686	295,985
Stock issued for benefit plans	0	0	0
Stock options exercised		0	0
Purchase of treasury shares	0	0	0
Tax benefits from stock-based compensation		0	0
Employee stock purchase plan	0	0	0
Issuance of restricted stock	0	0	0
Amortization of share-based compensation	0	0	0
Net Income (Loss)	$ (283,427)	$ (2,442)	$ 21,701