Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2014

Fair Value Measurements [Abstract]

Fair Value, by Balance Sheet Grouping

	Assets and Liabilities at Fair Value
	As of December 31, 2014
	Level 1		Level 2		Level 3		Total
	(in thousands)
Assets
Cash and cash equivalents	$	137,266	$	—	$	—	$	137,266
Short-term investments	201,521		552		—		202,073
Total cash and cash equivalents and investments	$	338,787	$	552	$	—	$	339,339
Liabilities
Other long-term liabilities	$	—	$	—	$	17,638	$	17,638
Total liabilities	$	—	$	—	$	17,638	$	17,638

	Assets and Liabilities at Fair Value
	As of December 31, 2013
	Level 1		Level 2		Level 3		Total
	(in thousands)
Assets
Cash and cash equivalents	$	37,499	$	—	$	—	$	37,499
Short-term investments	91,077		552		—		91,629
Total cash and cash equivalents and investments	$	128,576	$	552	$	—	$	129,128
Liabilities
Other long-term liabilities	$	—	$	—	$	27,710	$	27,710
Total liabilities	$	—	$	—	$	27,710	$	27,710

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation

	Other Long-term Liabilities
	(in thousands)
Balance at December 31, 2011	$	55,033
Change in valuation of purchase consideration payable to former Symphony Icon stockholders	9,887
Payment of base payment obligation with common stock	(35,000		)
Balance at December 31, 2012	29,920
Change in valuation of purchase consideration payable to former Symphony Icon stockholders	(2,210		)
Balance at December 31, 2013	27,710
Change in valuation of purchase consideration payable to former Symphony Icon stockholders	1,428
Payment of contingent payment obligation with common stock and cash	(11,500		)
Balance at December 31, 2014	$	17,638