Description of Business and Organization (Details) ft² in Millions	6 Months Ended
	Jun. 30, 2021 ft² parcel office_and_property
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Area of real estate property (in square feet)	10.1
Empire state realty trust | Empire state realty OP
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
OP units owned by the Company (as a percent)	60.70%
Office Building
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Area of real estate property (in square feet)	9.4
Number of properties | office_and_property	14
Office Building | Manhattan
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Area of real estate property (in square feet)	7.6
Number of properties | office_and_property	9
Office Building | Fairfield County, Connecticut and Westchester County, New York
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Area of real estate property (in square feet)	1.8
Number of properties | office_and_property	5
Long-term ground leasehold interests
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Number of properties | parcel	3
Retail Site | Manhattan and Westport, Connecticut
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Area of real estate property (in square feet)	0.2
Retail Site | Manhattan
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Area of real estate property (in square feet)	0.5
Number of properties | office_and_property	4
Retail Site | Westport, Connecticut
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Number of properties | office_and_property	2
Other Property | Stamford, Connecticut
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Area of real estate property (in square feet)	0.4