CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Accumulated Deficit [Member]	AOCI Attributable to Parent [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Treasury Stock [Member]
Beginning Balance at Dec. 31, 2012	$ 313,971	$ (504,072)	$ 0	$ 2,097	$ 815,946	$ 0
Beginning 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)					$ (122)
Repurchase of common stock (in shares)						8
Share of other comprehensive loss of equity method investments	0
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	(25,036)					$ (25,036)
Repurchase of common stock (in shares)						1,194
Conversion of convertible senior debentures to common stock	29				29
Conversion of convertible senior debentures to common stock (in shares)				2
Share of other comprehensive loss of equity method investments	0
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
Net loss	(59,524)	(59,524)
Stock options exercised, net	676				(1,051)	$ 1,727
Stock options exercised, net (in shares)						83
Issuance of restricted stock, net	158				(2,883)	$ 3,041
Issuance of restricted stock, net (in shares)						149
Stock-based compensation expense	1,611				1,611
Repurchase of common stock	(4,997)					$ (4,997)
Repurchase of common stock (in shares)						304
Share of other comprehensive loss of equity method investments	(246)		(246)
Ending Balance at Dec. 31, 2015	$ 195,505	$ (604,270)	$ (246)	$ 2,157	$ 817,434	$ (19,570)
Ending Balance (in shares) at Dec. 31, 2015				21,573		993