Leases - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from finance leases	$ 3,827
Operating cash flows from operating leases	90,629
Financing cash flows from finance leases	$ 1,640	$ 0