Lease Obligations - Future Sublease Payments for Ground Lease Rentals (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Lessor, Operating Lease, Payments, Fiscal Year Maturity [Abstract]
2020	$ 335,451
2021	292,146
2022	238,559
2023	191,552
2024	144,329
Thereafter	451,531
Total	1,653,568
Capital Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Finance lease		$ 14,382
2019		22,528
2020		20,903
2021		18,886
2022		17,245
2023		15,128
Thereafter		43,439
Total		$ 138,129
Lessee, Finance Leases, Sublease Rentals [Member]
Lessor, Operating Lease, Payments, Fiscal Year Maturity [Abstract]
Finance lease	10,279
Lessee, Operating Leases, Sublease Rentals [Member]
Lessor, Operating Lease, Payments, Fiscal Year Maturity [Abstract]
2020	24,137
2021	22,168
2022	20,400
2023	18,583
2024	13,567
Thereafter	39,111
Total	$ 137,966