CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (USD $) In Thousands	Total	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Treasury Stock [Member]
Beginning Balance at Dec. 31, 2011	$ 348,280	$ (464,710)	$ (41)	$ 2,075	$ 810,956	$ 0
Beginning Balance (in shares) at Dec. 31, 2011				20,752		0
Net loss	(39,362)	(39,362)
Stock options exercised, net	1,741			19	1,722
Stock options exercised, net (in shares)				181
Issuance of restricted stock, net	94			3	91
Issuance of restricted stock, net (in shares)				(35)
Stock-based compensation expense	2,014				2,014
Repurchase of common stock	(5,283)				(5,283)
Equity component of convertible senior debentures issued, net of issuance costs	6,446				6,446
Other comprehensive income	41		41
Ending Balance at Dec. 31, 2012	313,971	(504,072)	0	2,097	815,946	0
Ending Balance (in shares) at Dec. 31, 2012				20,968		0
Net loss	(35,525)	(35,525)
Stock options exercised, net	4,417			55	4,261	101
Stock options exercised, net (in shares)				559		7
Issuance of restricted stock, net	99			3	75	21
Issuance of restricted stock, net (in shares)				(26)		(3)
Stock-based compensation expense	1,821				1,821
Repurchase of common stock	(122)				0
Repurchase of common stock (in shares)						8
Repurchase of common stock						(122)
Ending Balance at Dec. 31, 2013	284,661	(539,597)	0	2,155	822,103	0
Ending Balance (in shares) at Dec. 31, 2013				21,553		4
Net loss	(5,149)	(5,149)
Stock options exercised, net	1,289			2	(2,716)	4,003
Stock options exercised, net (in shares)				18		198
Issuance of restricted stock, net	98				(1,594)	1,692
Issuance of restricted stock, net (in shares)						(79)
Stock-based compensation expense	1,935				1,935
Repurchase of common stock (in shares)						1,194
Repurchase of common stock	(25,036)					(25,036)
Conversion of convertible senior debentures to common stock	29				29
Conversion of convertible senior debentures to common stock (in shares)				2
Ending Balance at Dec. 31, 2014	$ 257,827	$ (544,746)	$ 0	$ 2,157	$ 819,757	$ (19,341)
Ending Balance (in shares) at Dec. 31, 2014				21,573		921