Revenue (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)
Revenue from Contract with Customer [Abstract]
Weighted Average Remaining Term Of Tenant Leases at the Tenant's Option	5 years
Operating Leases, Future Minimum Payments Receivable, 2019	$ 3,968
Operating Leases, Future Minimum Payments Receivable, 2020	3,761
Operating Leases, Future Minimum Payments Receivable, 2021	3,552
Operating Leases, Future Minimum Payments Receivable, 2022	3,317
Operating Leases, Future Minimum Payments Receivable, in 2023	2,587
Operating Leases, Future Minimum Payments Receivable, Thereafter	6,229
Operating Leases, Future Minimum Payments Receivable	$ 23,414