Real Estate Investments, Net (Summary of Intangible Lease Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Intangible assets:
Gross Carrying Amount	$ 269,616	$ 256,452
Accumulated Amortization	167,073	155,742
Net Carrying Amount	102,543	100,710
Market lease liabilities
Gross Carrying Amount	21,777	26,241
Accumulated Amortization	9,725	9,137
Net Carrying Amount	12,052	17,104
In-place leases
Intangible assets:
Gross Carrying Amount	229,300	214,953
Accumulated Amortization	156,428	144,669
Net Carrying Amount	72,872	70,284
Market lease assets
Intangible assets:
Gross Carrying Amount	13,616	30,910
Accumulated Amortization	9,501	9,970
Net Carrying Amount	4,115	20,940
Other intangible assets
Intangible assets:
Gross Carrying Amount	26,700	10,589
Accumulated Amortization	1,144	1,103
Net Carrying Amount	$ 25,556	$ 9,486