Business Segment Information - Revenue By Geographic Location (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Net revenues	$ 158,356	$ 212,575	$ 204,625	$ 164,262	$ 163,266	$ 163,260	$ 150,329	$ 104,528	$ 739,818	$ 581,383	$ 487,582
United States
Segment Reporting Information [Line Items]
Net revenues									271,260	283,933	298,279
United Kingdom
Segment Reporting Information [Line Items]
Net revenues									194,434	155,954	123,581
Brazil
Segment Reporting Information [Line Items]
Net revenues									208,054	70,710	2,543
Other
Segment Reporting Information [Line Items]
Net revenues									$ 66,070	$ 70,786	$ 63,179