Income Taxes - Reconciliation of Tax Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Statutory tax rate	12.50%	33.30%	33.30%
Non-deductible changes in fair value of contingent consideration	(165.00%)	11.90%	(24.80%)
Change in valuation allowance	11.80%	(9.60%)	5.30%
Income tax deferred charge	(9.70%)	1.30%	(16.90%)
International tax rates differential	(31.90%)	11.00%	6.70%
Nondeductible stock based compensation	(14.80%)	1.30%	(0.80%)
Cross-border merger	(100.60%)	0.00%	0.00%
Unrecognized tax benefit	(15.20%)	0.40%	0.00%
State and local taxes (net of federal)	(9.60%)	1.50%	0.30%
Other	(2.30%)	(4.90%)	(2.30%)
Effective income tax rate	(324.80%)	46.20%	0.80%
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income tax provision (benefit) - at statutory tax rate	$ (1,215)	$ 25,876	$ (30,013)
Non-deductible changes in fair value of contingent consideration	16,036	9,249	22,326
Change in valuation allowance	(1,143)	(7,425)	(4,732)
Income tax deferred charge	938	980	15,273
International tax rates differential	3,097	8,547	(6,023)
Nondeductible stock based compensation	1,436	1,004	693
Cross-border merger	9,773	0	0
Unrecognized tax benefit	1,475	290	0
State and local taxes (net of federal)	934	1,170	(228)
Other	227	(3,784)	2,060
Income tax provision (benefit)	$ 31,558	$ 35,907	$ (644)