Supplemental Information - Schedule of Revenues by Geographic Region (Parenthetical) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Revenues From External Customers And Long Lived Assets [Line Items]
Net revenues	$ 86,713	$ 61,514	$ 160,022	$ 113,639	$ 248,069
Germany
Revenues From External Customers And Long Lived Assets [Line Items]
Net revenues	$ 22,139	$ 17,651	$ 42,377	$ 31,009	$ 67,849