Segment Reporting Reportable Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015 segment	Mar. 31, 2014	Dec. 31, 2014
Segment Reporting Information [Line Items]
Rental revenue	$ 110,058	$ 90,204
Intercompany rental revenue	0esrt_IntercompanyRentalRevenue	0esrt_IntercompanyRentalRevenue
Tenant expense reimbursement	18,200us-gaap_TenantReimbursements	15,153us-gaap_TenantReimbursements
Observatory revenue	18,223esrt_ObservatoryRevenue	17,301esrt_ObservatoryRevenue
Construction revenue	1,607us-gaap_ConstructionRevenue	14,963us-gaap_ConstructionRevenue
Third-party management and other fees	446us-gaap_ManagementFeesRevenue	611us-gaap_ManagementFeesRevenue
Other revenue and fees	3,348us-gaap_OtherRealEstateRevenue	2,074us-gaap_OtherRealEstateRevenue
Total revenues	151,882us-gaap_Revenues	140,306us-gaap_Revenues
Property operating expenses	42,452us-gaap_OperatingCostsAndExpenses	35,860us-gaap_OperatingCostsAndExpenses
Intercompany rent expense	0esrt_IntercompanyRentExpense	0esrt_IntercompanyRentExpense
Ground rent expenses	2,331esrt_GroundRentExpense	451esrt_GroundRentExpense
Marketing, general, and administrative expenses	9,100	10,155
Observatory expenses	6,977esrt_ObservatoryExpense	6,981esrt_ObservatoryExpense
Construction expenses	2,869us-gaap_ConstructionAndDevelopmentCosts	14,283us-gaap_ConstructionAndDevelopmentCosts
Real estate taxes	22,978us-gaap_RealEstateTaxExpense	18,373us-gaap_RealEstateTaxExpense
Depreciation and amortization	41,418us-gaap_DepreciationAndAmortization	30,115us-gaap_DepreciationAndAmortization
Total operating expenses	128,125us-gaap_OperatingExpenses	116,218us-gaap_OperatingExpenses
Total operating income	23,757us-gaap_OperatingIncomeLoss	24,088us-gaap_OperatingIncomeLoss
Interest expense	(16,047)us-gaap_InterestExpense	(14,337)us-gaap_InterestExpense
Income before income taxes	7,710	9,751
Income tax (expense) benefit	178us-gaap_IncomeTaxExpenseBenefit	1,480us-gaap_IncomeTaxExpenseBenefit
Net income	7,888us-gaap_ProfitLoss	11,231us-gaap_ProfitLoss
Segment assets	3,272,988us-gaap_Assets	2,450,416us-gaap_Assets	3,296,495us-gaap_Assets
Expenditures for segment assets	37,393	17,243
Number of reportable segments	2us-gaap_NumberOfReportableSegments
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Rental revenue	0	0
Intercompany rental revenue	(11,664)	(15,268)
Tenant expense reimbursement	0	0
Observatory revenue	0	0
Construction revenue	(2,315)	(962)
Third-party management and other fees	0	0
Other revenue and fees	0	0
Total revenues	(13,979)	(16,230)
Property operating expenses	0	0
Intercompany rent expense	(11,664)	(15,268)
Ground rent expenses	0	0
Marketing, general, and administrative expenses	0	0
Observatory expenses	0	0
Construction expenses	(2,104)	(832)
Real estate taxes	0	0
Depreciation and amortization	0	0
Total operating expenses	(13,768)	(16,100)
Total operating income	(211)	(130)
Interest expense	0	0
Income before income taxes	(211)	(130)
Income tax (expense) benefit	0	0
Net income	(211)	(130)
Segment assets	0	0
Expenditures for segment assets	0	0
Real Estate, Segment [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Rental revenue	110,058	90,204
Intercompany rental revenue	11,664	15,268
Tenant expense reimbursement	18,200	15,153
Observatory revenue	0	0
Construction revenue	0	0
Third-party management and other fees	446	611
Other revenue and fees	3,348	2,074
Total revenues	143,716	123,310
Property operating expenses	42,452	35,860
Intercompany rent expense	0	0
Ground rent expenses	2,331	451
Marketing, general, and administrative expenses	9,100	10,155
Observatory expenses	0	0
Construction expenses	0	0
Real estate taxes	22,978	18,373
Depreciation and amortization	41,233	30,051
Total operating expenses	118,094	94,890
Total operating income	25,622	28,420
Interest expense	(16,047)	(14,337)
Income before income taxes	9,575	14,083
Income tax (expense) benefit	(351)	(300)
Net income	9,224	13,783
Segment assets	3,017,669	2,191,390
Expenditures for segment assets	37,393	17,243
Observatory, Segment [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Rental revenue	0	0
Intercompany rental revenue	0	0
Tenant expense reimbursement	0	0
Observatory revenue	18,223	17,301
Construction revenue	0	0
Third-party management and other fees	0	0
Other revenue and fees	0	0
Total revenues	18,223	17,301
Property operating expenses	0	0
Intercompany rent expense	11,664	15,268
Ground rent expenses	0	0
Marketing, general, and administrative expenses	0	0
Observatory expenses	6,977	6,981
Construction expenses	0	0
Real estate taxes	0	0
Depreciation and amortization	79	61
Total operating expenses	18,720	22,310
Total operating income	(497)	(5,009)
Interest expense	0	0
Income before income taxes	(497)	(5,009)
Income tax (expense) benefit	256	2,203
Net income	(241)	(2,806)
Segment assets	251,662	245,999
Expenditures for segment assets	0	0
Other Segments [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Rental revenue	0	0
Intercompany rental revenue	0	0
Tenant expense reimbursement	0	0
Observatory revenue	0	0
Construction revenue	3,922	15,925
Third-party management and other fees	0	0
Other revenue and fees	0	0
Total revenues	3,922	15,925
Property operating expenses	0	0
Intercompany rent expense	0	0
Ground rent expenses	0	0
Marketing, general, and administrative expenses	0	0
Observatory expenses	0	0
Construction expenses	4,973	15,115
Real estate taxes	0	0
Depreciation and amortization	106	3
Total operating expenses	5,079	15,118
Total operating income	(1,157)	807
Interest expense	0	0
Income before income taxes	(1,157)	807
Income tax (expense) benefit	273	(423)
Net income	(884)	384
Segment assets	3,657	13,027
Expenditures for segment assets	$ 0	$ 0

Ground Rent Expense

No definition available.

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- Definition

Intercompany Rental Revenue

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No definition available.

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- Definition

Intercompany Rent Expense

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No definition available.

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- Definition

Observatory Expense

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No definition available.

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- Definition

Observatory Revenue

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No definition available.

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- Definition

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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- Definition

The aggregate costs related to construction and development services during the reporting period.

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The aggregate revenue from building and real estate development, which may include improvements (such as drainage, utilities, grading and subdividing) to a parcel of land, and general contracting services during the reporting period.

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- Definition

The current period expense charged against earnings on long-lived, physical assets not used in production, and which are not intended for resale, to allocate or recognize the cost of such assets over their useful lives; or to record the reduction in book value of an intangible asset over the benefit period of such asset; or to reflect consumption during the period of an asset that is not used in production.

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This element represents the income or loss from continuing operations attributable to the economic entity which may also be defined as revenue less expenses from ongoing operations, after income or loss from equity method investments, but before income taxes, extraordinary items, and noncontrolling interest.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of the cost of borrowed funds accounted for as interest expense.

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- Definition

Revenue, comprised of base and incentive revenue derived from the management of joint ventures, managing third-party properties, or another entity's operations.

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- Definition

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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No definition available.

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- Definition

Generally recurring costs associated with normal operations except for the portion of these expenses which can be clearly related to production and included in cost of sales or services. Excludes Selling, General and Administrative Expense.

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No definition available.

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Generally recurring costs associated with normal operations except for the portion of these expenses which can be clearly related to production and included in cost of sales or services. Includes selling, general and administrative expense.

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No definition available.

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The net result for the period of deducting operating expenses from operating revenues.

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No definition available.

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The total amount of revenue recognized for the period from operating leases, including minimum lease revenue, contingent revenue, percentage revenue and sublease revenue.

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Other real estate revenue not otherwise specified in the taxonomy.

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The cash outflow for purchases of and capital improvements on property, plant and equipment (capital expenditures), software, and other intangible assets.

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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A tax based on the assessed value of real estate by the local government. The tax is usually based on the value of property (including the land).

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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The aggregate total costs related to selling a firm's product and services, as well as all other general and administrative expenses. Direct selling expenses (for example, credit, warranty, and advertising) are expenses that can be directly linked to the sale of specific products. Indirect selling expenses are expenses that cannot be directly linked to the sale of specific products, for example telephone expenses, Internet, and postal charges. General and administrative expenses include salaries of non-sales personnel, rent, utilities, communication, etc.

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In accordance with the provisions of their lease agreement, this element represents allowable charges due a landlord from its tenant. In retail store and office building leases, for example, tenant reimbursements may cover items such as taxes, utilities, and common area expenses.

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