Commitments and Contingencies (Litigation and contingencies) (Details) ft² in Thousands, $ in Thousands	1 Months Ended		12 Months Ended
	Mar. 31, 2016 USD ($)	Feb. 28, 2014 fire	Dec. 31, 2021 USD ($) ft²
Commitments And Contingencies Disclosure
Standby letters of credit, outstanding			$ 960
Rego Park I | Sears
Commitments And Contingencies Disclosure
Area of land | ft²			195
Number of fires | fire		2
Minimum | Rego Park I | Sears
Commitments And Contingencies Disclosure
Loss contingency, damages sought, value			$ 4,000
Estimated Future Damages | Rego Park I | Sears
Commitments And Contingencies Disclosure
Loss contingency, damages sought, value	$ 650
Estimated Future Damages | Minimum | Rego Park I | Sears
Commitments And Contingencies Disclosure
Loss contingency, damages sought, value			25,000
Estimated Future Damages | Maximum | Rego Park I | Sears
Commitments And Contingencies Disclosure
Loss contingency, estimate of possible loss			$ 650