Leases (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Lessor, Lease, Description [Line Items]
Weighted average remaining lease term, operating lease	13 years
Weighted average remaining lease term, finance lease	25 years
Incremental borrowing rate, operating lease	4.10%
Incremental borrowing rate, finance lease	3.90%
Lease revenue			$ 3,000,000
Revenues	$ 814,515	$ 744,368
Initial direct costs			37,000
Rental and other services
Lessor, Lease, Description [Line Items]
Revenues	812,030	592,298	2,100,000
Tenant reimbursements
Lessor, Lease, Description [Line Items]
Revenues	$ 0	$ 150,079	$ 600,000