Leases - Additional information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2020 USD ($) Counterparty	Jun. 01, 2020 Lease	Dec. 31, 2019 USD ($)
Operating Leased Assets [Line Items]
Number of lease agreements, sell and lease back | Counterparty		3
Number of lease agreements | Lease			2
Operating lease right-of-use assets		$ 505,064		$ 145,813
Operating lease, liability		436,121
Prepaid lease costs reclassified as other deferred debits		34,983		33,400
Deferred lease costs		187,448		$ 168,323
Operating lease, expense	$ 18,000
Lease not yet commenced		650,000
Purchased Power Lease Contracts
Operating Leased Assets [Line Items]
Operating lease, liability		$ 372,763
Operating lease, expense	47,000
Contingent rentals	$ 109,000