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Leases - Operating Leases - Vehicle fleet leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Apr. 30, 2018
Operating leases
Restricted cash, noncurrent	$ 971	$ 6,426
Operating lease cost	16,452
Vehicles, 2018 Vehicle Leases
Operating leases
Operating lease, term			12 months
Operating lease, renewal term			1 month
Restricted cash, noncurrent			$ 1,300
Operating lease cost	$ 1,500	800
Vehicles
Operating leases
Capital lease obligations		$ 0