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)
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	4,634	$ 0	4,634	0	0	0
Issuance of common stock under Equity Incentive Plans, shares		461
Issuance of common stock under Equity Incentive Plans, value	5,427	$ 0	5,427	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	(69,950)	0	0	(69,950)	0	0
Unrealized gain (loss) on investments	(19)	$ 0	0	0	(19)	0
Balance, shares at Jun. 30, 2017		105,703
Balance, value at Jun. 30, 2017	106,313	$ 105	1,430,630	(1,322,304)	(214)	(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	5,972	$ 0	5,972	0	0	0
Issuance of common stock under Equity Incentive Plans, shares		404
Issuance of common stock under Equity Incentive Plans, value	392	$ 0	392	0	0	0
Repurchase of common stock	(972)	0	0	0	0	(972)
Net loss	(76,781)	0	0	(76,781)	0	0
Unrealized gain (loss) on investments	4	$ 0	0	0	4	0
Balance, shares at Jun. 30, 2018		106,115
Balance, value at Jun. 30, 2018	$ (5,071)	$ 106	$ 1,441,890	$ (1,443,973)	$ (218)	$ (2,876)