Commitments and Contingencies (Narrative) (Details)		3 Months Ended	12 Months Ended
	Jan. 13, 2017 plaintiff	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($) lease	Dec. 31, 2018 USD ($)
Lessee, Lease, Description [Line Items]
Number of properties subject to ground leases | lease			8
Operating lease right-of-use assets			$ 18,959,000
Operating lease liabilities			$ 19,318,000
Weighted average remaining lease term			9 years
Prior period reclassification adjustment		$ 900,000
Legal costs			$ 1,300,000	$ 1,900,000
Insurance recoveries			$ (2,300,000)
Land
Lessee, Lease, Description [Line Items]
Weighted average remaining lease term			28 years 10 months 24 days
Discount rate			7.50%
Operating lease payments			$ 1,500,000
Operating lease cost			$ 2,700,000
Minimum | Land
Lessee, Lease, Description [Line Items]
Term of contract			18 years
Maximum | Land
Lessee, Lease, Description [Line Items]
Term of contract			44 years 9 months 18 days
Putative Class Action Lawsuit
Lessee, Lease, Description [Line Items]
Number of plaintiffs | plaintiff	4
Loss contingency accrual, provision			$ 0