Leases - Supplemental cash flow information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Leases
Operating cash flows from operating leases	$ 247,413	$ 301,524
Operating cash flows from finance leases	17,595	9,826
Financing cash flows from finance leases	49,231	31,841
Operating leases	$ 37,899	81,198
Finance leases		175,311
Right-of-use assets and liabilities recognized at January 1, 2019 upon adoption of ASC 842		$ 730,180