Leases - Lease Expense and Cash Outflows from Operating and Finance Leases (Details) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Leases [Abstract]
Operating lease cost	$ 9,707	$ 28,212
Short-term lease cost	397	910
Variable lease cost	715	2,405
Amortization	67	186
Interest on lease liabilities	5	12
Total lease cost	$ 10,891	31,725
Cash paid for amounts included in measurement of lease liabilities:
Operating cash flows from operating leases		28,023
Operating cash flows from finance leases		12
Financing cash flows from finance leases		182
Right-of-use assets obtained in exchange for lease obligations:
Operating leases		32,511
Finance leases		$ 159