Income Taxes (Tables)

12 Months Ended

Dec. 31, 2014

Income Taxes [Abstract]

Schedule of Deferred Tax Assets and Liabilities

	As of December 31,
	2014			2013
	(in thousands)
Deferred tax assets:
Net operating loss carryforwards	$	255,518		$	238,608
Research and development tax credits	40,173			37,453
Capitalized research and development	95,946			83,375
Stock-based compensation	7,648			7,703
Deferred revenue	4,457			4,760
Other	8,681			4,712
Total deferred tax assets	412,423			376,611
Deferred tax liabilities:
Deferred tax liability related to acquisition of Symphony Icon	(18,675		)	(18,745		)
Total deferred tax liabilities	(18,675		)	(18,745		)
Less: valuation allowance	(412,423		)	(376,611		)
Net deferred tax liabilities	$	(18,675	)	$	(18,745	)