Fair Value Measurements - Schedule of Changes in Level 3 Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Contingent consideration assumed in asset acquisition	$ 0	$ 3,660	$ 0
Payment of contingent consideration	0	(1,583)	0
Significant Unobservable Inputs (Level 3)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	2,081	0
Contingent consideration assumed in asset acquisition	585	3,660
Payment of contingent consideration	0	(1,583)
Change in fair value of contingent consideration	(2,081)	4
Ending Balance	$ 585	$ 2,081	$ 0