Real Estate Investments (Summary of Amortization and Accretion of Market Lease Assets and Liabilities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Amortization and (accretion) of above- and below-market leases, net	$ (1,563)	$ (2,044)	$ (2,247)
Depreciation and Amortization
Finite-Lived Intangible Assets [Line Items]
Amortization of leases and other intangibles	10,509	11,319	12,669
Depreciation and Amortization | In-place leases
Finite-Lived Intangible Assets [Line Items]
Amortization of leases and other intangibles	9,344	10,154	11,503
Depreciation and Amortization | Other intangibles
Finite-Lived Intangible Assets [Line Items]
Amortization of leases and other intangibles	1,165	1,165	1,166
Rental Income
Finite-Lived Intangible Assets [Line Items]
Amortization of below market lease	(3,213)	(3,532)	(3,775)
Rental Income | Above-market leases
Finite-Lived Intangible Assets [Line Items]
Amortization of leases and other intangibles	(1,602)	(1,438)	(1,479)
Rental Income | Amortization and (accretion) of above- and below-market leases, net
Finite-Lived Intangible Assets [Line Items]
Amortization and (accretion) of above- and below-market leases, net	1,611	2,094	2,296
Operating Expense | Amortization of below-market ground lease
Finite-Lived Intangible Assets [Line Items]
Amortization of leases and other intangibles	$ 48	$ 50	$ 49