Fair Value Measurements - Reconciliation of Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Common stock warrant liabilities	$ 222		$ 809
Contingent consideration	53,400		52,800
Contingent Consideration Liabilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		$ 51,000
Changes in fair value	600	1,300
Ending Balance		52,300
Contingent consideration			$ 52,800
Common Stock Warrant Liabilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		6,196
Changes in fair value	$ (587)	(4,527)
Ending Balance		$ 1,669