Lease Obligations - Lease Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Operating lease liabilities
2021	$ 120,376
2022	117,783
2023	115,532
2024	110,853
2025	103,471
Thereafter	765,838
Total lease payments	1,333,853
Less: Imputed interest	(466,893)
Total lease obligations	866,960
Less: Current portion	(62,405)	$ (58,613)
Operating lease liabilities - non-current	804,555	$ 843,312
Finance Lease, Liability, Payment, Due [Abstract]
2021	3,977
2022	4,011
2023	2,777
2024	2,494
2025	2,376
Thereafter	33,776
Total lease payments	49,411
Less: Imputed interest	(19,429)
Total lease liabilities	29,982
Less: Current portion	(2,240)
Noncurrent lease obligations	$ 27,742