Income Taxes (Tables)

12 Months Ended

Dec. 31, 2015

Income Taxes [Abstract]

Schedule of Deferred Tax Assets and Liabilities

	As of December 31,
	2015			2014
	(in thousands)
Deferred tax assets:
Net operating loss carryforwards	$	263,138		$	255,518
Research and development tax credits	43,728			40,173
Capitalized research and development	85,385			95,946
Stock-based compensation	8,160			7,648
Deferred revenue	4,363			4,457
Other	8,831			8,681
Total deferred tax assets	413,605			412,423
Deferred tax liabilities:
Deferred tax liability related to acquisition of Symphony Icon	(18,675		)	(18,675		)
Total deferred tax liabilities	(18,675		)	(18,675		)
Less: valuation allowance	(413,605		)	(412,423		)
Net deferred tax liabilities	$	(18,675	)	$	(18,675	)