Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Gain (Loss)	Treasury Stock
Balance, shares at Dec. 31, 2016		104,582
Balance, value at Dec. 31, 2016	$ 157,401	$ 105	$ 1,411,222	$ (1,250,363)	$ (195)	$ (3,368)
Cumulative effect from accounting change	0		1,991	(1,991)	0	0
Issuance of common stock to designees of Symphony Icon Holdings LLC, shares		660
Issuance of common stock to designees of Symphony Icon Holdings LLC, value	10,499	$ 0	10,499	0	0	0
Stock-based compensation	2,231	$ 0	2,231	0	0	0
Issuance of common stock under Equity Incentive Plans, shares		96
Issuance of common stock under Equity Incentive Plans, value	1,111	$ 0	1,111	0	0	0
Stock Issued During Period, Value, Treasury Stock Reissued	0		(3,143)	0	0	(3,143)
Repurchase of common stock	(1,679)	0	0	0	0	(1,679)
Net loss	(34,891)	0	0	(34,891)	0	0
Unrealized loss on investments	(69)	$ 0	0	0	(69)	0
Balance, shares at Mar. 31, 2017		105,338
Balance, value at Mar. 31, 2017	134,603	$ 105	1,423,911	(1,287,245)	(264)	(1,904)
Balance, shares at Dec. 31, 2017		105,711
Balance, value at Dec. 31, 2017	52,102	$ 106	1,435,526	(1,381,404)	(222)	(1,904)
Cumulative effect from accounting change	14,212	0	0	14,212	0	0
Issuance of common stock to designees of Symphony Icon Holdings LLC, value	0
Stock-based compensation	3,074	$ 0	3,074	0	0	0
Issuance of common stock under Equity Incentive Plans, shares		337
Issuance of common stock under Equity Incentive Plans, value	25	$ 0	25	0	0	0
Repurchase of common stock	(972)	0	0	0	0	(972)
Net loss	(42,075)	0	0	(42,075)	0	0
Unrealized loss on investments	(172)	$ 0	0	0	(172)	0
Balance, shares at Mar. 31, 2018		106,048
Balance, value at Mar. 31, 2018	$ 26,194	$ 106	$ 1,438,625	$ (1,409,267)	$ (394)	$ (2,876)