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	7,214	$ 0	7,214	0	0	0
Issuance of common stock under Equity Incentive Plans, shares		468
Issuance of common stock under Equity Incentive Plans, value	5,481	$ 1	5,480	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	(100,672)	0	0	(100,672)	0	0
Unrealized gain on investments	132	$ 0	0	0	132	0
Balance, shares at Sep. 30, 2017		105,710
Balance, value at Sep. 30, 2017	78,376	$ 106	1,433,263	(1,353,026)	(63)	(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	8,849	$ 0	8,849	0	0	0
Issuance of common stock under Equity Incentive Plans, shares		423
Issuance of common stock under Equity Incentive Plans, value	550	$ 0	550	0	0	0
Repurchase of common stock	(972)	0	0	0	0	(972)
Net loss	(104,293)	0	0	(104,293)	0	0
Unrealized gain on investments	151	$ 0	0	0	151	0
Balance, shares at Sep. 30, 2018		106,134
Balance, value at Sep. 30, 2018	$ (29,401)	$ 106	$ 1,444,925	$ (1,471,485)	$ (71)	$ (2,876)