Leases - Operating Leases - Vehicle Fleet Leases (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Apr. 30, 2018
Operating leases
Restricted cash, noncurrent	$ 971		$ 971		$ 971
Operating lease cost	633	$ 3,155	1,266	$ 7,680
Vehicles, 2018 Vehicle Leases
Operating leases
Operating lease, term						12 months
Operating lease, renewal term						1 month
Restricted cash, noncurrent	1,300		1,300		$ 1,300
Operating lease cost	$ 400	$ 400	$ 700	$ 800