Leases - Narratives (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Restricted funds	$ 160,823		$ 28,340
Rent expense	$ 14,200	$ 10,900
Lease Agreements
Lessee, Lease, Description [Line Items]
Letters of credit outstanding, amount			3,600
Restricted funds			$ 3,600