Supplemental Information - Schedule of Revenues by Geographic Region (Parenthetical) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Revenues From External Customers And Long Lived Assets [Line Items]
Net revenues	$ 61,514	$ 38,376	$ 113,639	$ 73,256	$ 177,026
Germany
Revenues From External Customers And Long Lived Assets [Line Items]
Net revenues	$ 17,651	$ 6,817	$ 31,009	$ 12,216	$ 40,215