Fair Value Measurement (Tables)

12 Months Ended

Dec. 31, 2014

Fair Value Disclosures [Abstract]

Schedule of Fair Value Assets Measured on Recurring Basis

The following table presents the balances of assets measured at fair value on a recurring basis as of December 31, 2014 and 2013:

	December 31, 2014						December 31, 2013
	Level 1		Level 2		Level 3		Level 1		Level 2		Level 3
	(in thousands)
Money market funds	$	—	$	1,386	$	—	$	—	$	—	$	—
Commercial paper		—		38,055		—		—		—		—
Corporate bonds		—		75,080		—		—		—		—
Redeemable common stock		—		—		—		—		—		18,415
Total	$	—	$	114,521	$	—	$	—	$	—	$	18,415

Schedule of Fair Value, Valuation Techniques and Related Unobservable Inputs

The following table presents the fair value, valuation techniques and related unobservable inputs for the Level 3 measurement as of December 31, 2013:

	Fair value measurement (Level 3) (in thousands)				Range
	December 31, 2013		Valuation technique	Unobservable input	December 31, 2013
Redeemable common stock	$	18,415	Probability-Weighted	Discount rate		15.3	%
			Expected Return Method	Lack of marketability per common share		14.9	%