Segment information - Revenues Generated in United States and All International Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Revenues	$ 516,105	$ 472,075	$ 956,005	$ 870,595
United States
Segment Reporting Information [Line Items]
Revenues	489,945	441,614	904,072	818,096
International
Segment Reporting Information [Line Items]
Revenues	$ 26,160	$ 30,461	$ 51,933	$ 52,499