Basis of Presentation and Significant Accounting Policies - Additional Information (Details)		12 Months Ended
	Jan. 01, 2018 USD ($)	Dec. 31, 2018 USD ($) Segment	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Feb. 29, 2016
Property Plant And Equipment [Line Items]
Minimum percentage of taxable income distributed to shareholders		90.00%
Income tax expense		$ 3,139,000	$ 5,177,000	$ 1,785,000
Number of reportable segments | Segment		3
Capitalized internal leasing costs		$ 5,653,000	7,003,000	5,027,000
Adjustment to investments in unconsolidated joint ventures		7,086,000
ASU 2016-02 [Member]
Property Plant And Equipment [Line Items]
Lease term, in months					12 months
ASU 2016-18 [Member]
Property Plant And Equipment [Line Items]
Increase in cash provided by used in operating activities continuing operations				3,000,000
Increase in cash provided by used in investing activities continuing operations				15,449,000
ASU 2017-05 [Member] | RDF [Member] | 75 Howard [Member]
Property Plant And Equipment [Line Items]
Adjustment to investments in unconsolidated joint ventures	$ 7,086,000
Taxable REIT Subsidiaries [Member]
Property Plant And Equipment [Line Items]
Income tax expense		622,000	5,758,000	780,000
Deferred income tax expense (benefit)		$ 87,000	$ 922,000	$ 479,000
Minimum [Member]
Property Plant And Equipment [Line Items]
Estimated useful lives of the assets, years		5
Maximum [Member]
Property Plant And Equipment [Line Items]
Estimated useful lives of the assets, years		40