Other Assets and Deferred Charges, Net (Components of Other Assets and Deferred Charges, Net) (Details) - USD ($)	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Deferred Costs And Other Assets [Line Items]
Lease origination costs	$ 19,947,000		$ 21,623,000
Right-of-use assets	13,638,000	$ 14,600,000
Interest rate swaps	136,000		8,871,000
Prepaid expenses	6,048,000		5,790,000
Unsecured revolving credit facility financing costs	2,769,000		3,536,000
Leasehold improvements, furniture and fixtures	200,000		359,000
Investments related to deferred compensation liabilities	823,000		616,000
Other	326,000		1,756,000
Total other assets and deferred charges, net	42,139,000		40,642,000
Intangible Lease Assets [Member]
Deferred Costs And Other Assets [Line Items]
Deferred charges, net	6,600,000		7,500,000
Cost of intangible lease assets	19,900,000		19,900,000
Accumulated amortization of intangible lease assets	13,300,000		12,400,000
Unsecured Revolving Credit Facility [Member]
Deferred Costs And Other Assets [Line Items]
Unsecured revolving credit facility financing costs	1,021,000		$ 1,627,000
Accumulated amortization of intangible lease assets	$ 32,800,000