Commitments and Contingencies - Lease Commitments (Details) $ in Thousands	3 Months Ended
Mar. 31, 2019 USD ($) property	Mar. 31, 2018 USD ($)
Lease Commitments
Properties subject to ground leases \| property	23
Lease Cost
Operating lease cost	$ 7,165
Variable lease cost	4,144
Sublease income	(167)
Total lease cost	11,142
Lease expense		$ 12,125
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases	$ 12,068
Weighted-average remaining lease term - operating leases	36 years 2 months 12 days
Weighted-average discount rate - operating leases	4.87%
Operating Lease Liabilities
2019	$ 32,444
2020	32,438
2021	32,722
2022	32,733
2023	32,864
Thereafter	949,754
Future minimum gross lease payments	1,112,955
Impact of discounting	(590,761)
Operating lease liabilities	$ 522,194

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