Deferred Acquisition Consideration (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2019
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Payments			$ 30,719
Redemption value adjustments	$ 3,483	$ 14,079	(2,617)
Additions			6,344
Foreign translation adjustment			35
Ending balance of contingent payments	55,641		55,641
Deferred acquisition consideration	56,190		56,190
Stock-based compensation	1,540	3,076	1,010	$ 7,758
Fixed payments
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Deferred acquisition consideration					$ 549
Contingent Payment
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
(Income) loss attributable to fair value adjustments	$ 1,943	$ 11,003	$ (3,627)	$ 8,522