Deferred Acquisition Consideration (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance of contingent payments			$ 82,598	$ 119,086
Payments			30,719	54,947
Redemption value adjustments			15,451	3,512
Additions			7,145	14,943
Foreign translation adjustment			196	4
Ending balance of contingent payments	$ 74,671	$ 82,598	74,671	82,598
Deferred acquisition consideration	75,220	83,695	75,220	83,695
Stock-based compensation			10,048	7,191
Fixed payments
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Deferred acquisition consideration	549	1,097	549	1,097
Contingent Payment
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
(Income) loss attributable to fair value adjustments	$ 9,030	$ (8,979)	$ 5,403	$ (3,679)