Empire State Realty Trust (ESRT) 10-K 28 Feb 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Feb. 22, 2019	Jun. 29, 2018
Entity Registrant Name	Empire State Realty Trust, Inc.
Entity Central Index Key	1,541,401
Document Type	10-K
Current Fiscal Year End Date	--12-31
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Entity Filer Category	Large Accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Class A Common Stock
Entity Common Stock, Shares Outstanding		175,039,980
Entity Public Float			$ 2,849,868,000
Class B Common Stock
Entity Common Stock, Shares Outstanding		1,037,574

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Commercial real estate properties, at cost:
Land	$ 201,196	$ 201,196
Development costs	7,987	7,986
Building and improvements	2,675,303	2,458,473
Commercial real estate properties, at cost, gross	2,884,486	2,667,655
Less: accumulated depreciation	(747,304)	(656,900)
Commercial real estate properties, net	2,137,182	2,010,755
Cash and cash equivalents	204,981	464,344
Restricted cash	65,832	65,853
Short-term investments	400,000	0
Tenant and other receivables, net of allowance of $488 and $1,422 in 2018 and 2017, respectively	29,437	28,329
Deferred rent receivables, net of allowance of $19 and $185 in 2018 and 2017, respectively	200,903	178,629
Prepaid expenses and other assets	64,345	61,028
Deferred costs, net	241,223	262,701
Acquired below market ground leases, net	360,398	368,229
Goodwill	491,479	491,479
Total assets	4,195,780	3,931,347
Liabilities:
Mortgage notes payable, net	608,567	717,164
Senior unsecured notes, net	1,046,219	707,895
Unsecured term loan facility, net	264,147	263,662
Unsecured revolving credit facility	0	0
Accounts payable and accrued expenses	130,676	110,849
Acquired below market leases, net	52,450	66,047
Deferred revenue and other liabilities	44,810	40,907
Tenants’ security deposits	57,802	47,086
Total liabilities	2,204,671	1,953,610
Commitments and contingencies
Empire State Realty Trust, Inc. stockholders' equity:
Preferred stock, $0.01 par value per share, 50,000,000 shares authorized, none issued or outstanding	0	0
Additional paid-in capital	1,204,075	1,128,460
Accumulated other comprehensive loss	(8,853)	(8,555)
Retained earnings	41,511	46,762
Total Empire State Realty Trust, Inc.'s stockholders' equity	1,238,482	1,168,282
Non-controlling interests in operating partnership	744,623	801,451
Private perpetual preferred units, $16.62 per unit liquidation preference, 1,560,360 issued and outstanding in 2018 and 2017	8,004	8,004
Total equity	1,991,109	1,977,737
Total liabilities and equity	4,195,780	3,931,347
Class A Common Stock
Empire State Realty Trust, Inc. stockholders' equity:
Common stock	1,739	1,604
Class B Common Stock
Empire State Realty Trust, Inc. stockholders' equity:
Common stock	$ 10	$ 11

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Tenant and other receivables allowance	$ 488	$ 1,422
Deferred rent receivables allowance	$ 19	$ 185
Preferred stock, par value (USD per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	50,000,000	50,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Private perpetual preferred units, liquidation preference per share (in dollars per share)	$ 16.62	$ 16.62
Private perpetual preferred units, issued, shares	1,560,360	1,560,360
Private perpetual preferred units, outstanding, shares	1,560,360	1,560,360
Class A Common Stock
Common stock, par value (USD per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	400,000,000	400,000,000
Common stock, shares issued (in shares)	173,872,536	160,424,575
Common stock, shares outstanding (in shares)	173,872,536	160,424,575
Class B Common Stock
Common stock, par value (USD per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	50,000,000	50,000,000
Common stock, shares issued (in shares)	1,038,090	1,052,469
Common stock, shares outstanding (in shares)	1,038,090	1,052,469

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues:
Rental revenue													$ 493,231	$ 483,944	$ 460,653
Tenant expense reimbursement													72,372	73,679	73,459
Observatory revenue													131,227	127,118	124,814
Lease termination fees													20,847	13,551	7,676
Third-party management and other fees													1,440	1,400	1,766
Other revenue and fees													12,394	9,834	8,985
Total revenues	$ 199,309	$ 186,402	$ 178,529	$ 167,271	$ 182,297	$ 186,547	$ 176,349	$ 164,333	$ 178,807	$ 175,704	$ 165,785	$ 157,057	731,511	709,526	677,353
Operating expenses:
Property operating expenses													167,379	163,531	153,850
Ground rent expenses													9,326	9,326	9,326
General and administrative expenses													52,674	50,315	49,078
Observatory expenses													32,767	30,275	29,833
Real estate taxes													110,000	102,466	96,061
Acquisition expenses													0	0	98
Depreciation and amortization													168,508	160,710	155,211
Total operating expenses													540,654	516,623	493,457
Total operating income (loss)	58,490	48,538	49,665	34,164	50,191	56,008	50,659	36,045	52,195	53,442	44,162	34,097	190,857	192,903	183,896
Other income (expense):
Interest income													10,661	2,942	647
Interest expense													(79,623)	(68,473)	(70,595)
Loss on early extinguishment of debt													0	(2,157)	(552)
Loss from derivative financial instruments													0	(289)	0
Income before income taxes													121,895	124,926	113,396
Income tax expense													(4,642)	(6,673)	(6,146)
Net income	$ 39,781	$ 29,230	$ 30,184	$ 18,058	$ 32,260	$ 35,489	$ 31,359	$ 19,145	$ 33,008	$ 32,897	$ 24,640	$ 16,705	117,253	118,253	107,250
Private perpetual preferred unit distributions													(936)	(936)	(936)
Net income attributable to non-controlling interests													(50,714)	(54,670)	(54,858)
Net income attributable to common stockholders													$ 65,603	$ 62,647	$ 51,456
Total weighted average shares:
Basic (in shares)													167,571	158,380	133,881
Diluted (in shares)													297,259	298,049	277,568
Earnings per share attributable to common stockholders:
Basic (USD per share)													$ 0.39	$ 0.40	$ 0.38
Diluted (USD per share)													$ 0.39	$ 0.39	$ 0.38

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 117,253	$ 118,253	$ 107,250
Other comprehensive loss:
Unrealized loss on valuation of interest rate swap agreements	(2,721)	(11,658)
Unrealized loss on valuation of interest rate swap agreements			(3,054)
Amount reclassified into interest expense	1,845	1,142
Amount reclassified into interest expense			0
Other comprehensive loss	(876)	(10,516)	(3,054)
Comprehensive income	116,377	107,737	104,196
Net income attributable to non-controlling interests and private perpetual preferred unitholders	(51,650)	(55,606)	(55,794)
Other comprehensive loss attributable to non-controlling interests	382	4,901	1,576
Comprehensive income attributable to common stockholders	$ 65,109	$ 57,032	$ 49,978

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Class A Common Stock	Class B Common Stock	Total Stockholders' Equity	Common StockClass A Common Stock	Common StockClass B Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Non-controlling Interests	Private Perpetual Preferred Units
Beginning balance (in shares) at Dec. 31, 2015					118,903,000	1,120,000
Beginning balance at Dec. 31, 2015	$ 1,372,686			$ 524,729	$ 1,189	$ 11	$ 469,152	$ (883)	$ 55,260	$ 839,953	$ 8,004
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Class A shares, net of costs (in shares)					29,610,854
Issuance of Class A shares, net of costs	611,206			611,206	$ 296		610,910
Conversion of operating partnership units and Class B shares to Class A shares (in shares)					6,191,000	(24,000)
Conversion of operating partnership units and Class B shares to Class A shares	0			23,678	$ 62		24,044	(428)		(23,678)
Equity compensation:
LTIP Units, net of forfeitures	9,372									9,372
Restricted stock, net of forfeitures (in shares)					40,000
Restricted stock, net of forfeitures	357			357			357
Dividends and distributions	(114,954)			(55,812)					(55,812)	(58,206)	(936)
Net income	107,250			51,456					51,456	54,858	936
Other comprehensive income (loss)	(3,054)			(1,478)				(1,478)		(1,576)
Ending balance (in shares) at Dec. 31, 2016					154,745,000	1,096,000
Ending balance at Dec. 31, 2016	1,982,863			1,154,136	$ 1,547	$ 11	1,104,463	(2,789)	50,904	820,723	8,004
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of operating partnership units and Class B shares to Class A shares (in shares)					5,659,000	(44,000)
Conversion of operating partnership units and Class B shares to Class A shares	0			23,435	$ 57		23,529	(151)		(23,435)
Equity compensation:
LTIP Units, net of forfeitures	13,632									13,632
Restricted stock, net of forfeitures (in shares)					21,000
Restricted stock, net of forfeitures	468			468			468
Dividends and distributions	(126,963)			(66,789)					(66,789)	(59,238)	(936)
Net income	118,253			62,647					62,647	54,670	936
Other comprehensive income (loss)	(10,516)			(5,615)				(5,615)		(4,901)
Ending balance (in shares) at Dec. 31, 2017		160,424,575	1,052,469		160,425,000	1,052,000
Ending balance at Dec. 31, 2017	1,977,737			1,168,282	$ 1,604	$ 11	1,128,460	(8,555)	46,762	801,451	8,004
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Class A shares, net of costs (in shares)					284,000
Issuance of Class A shares, net of costs	4,749			4,749	$ 3		4,746
Conversion of operating partnership units and Class B shares to Class A shares (in shares)					13,141,000	(14,000)
Conversion of operating partnership units and Class B shares to Class A shares	0			70,779	$ 132	$ (1)	70,452	196		(70,779)
Equity compensation:
LTIP Units, net of forfeitures	18,368									18,368
Restricted stock, net of forfeitures (in shares)					24,000
Restricted stock, net of forfeitures	417			417			417
Dividends and distributions	(126,539)			(70,854)					(70,854)	(54,749)	(936)
Net income	117,253			65,603					65,603	50,714	936
Other comprehensive income (loss)	(876)			(494)				(494)		(382)
Ending balance (in shares) at Dec. 31, 2018		173,872,536	1,038,090		173,874,000	1,038,000
Ending balance at Dec. 31, 2018	$ 1,991,109			$ 1,238,482	$ 1,739	$ 10	$ 1,204,075	$ (8,853)	$ 41,511	$ 744,623	$ 8,004

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash Flows From Operating Activities
Net income	$ 117,253	$ 118,253	$ 107,250
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	168,508	160,710	155,211
Amortization of non-cash items within interest expense	7,215	1,039	739
Amortization of acquired above and below-market leases, net	(6,120)	(5,721)	(8,795)
Amortization of acquired below-market ground leases	7,831	7,831	7,831
Straight-lining of rental revenue	(22,107)	(26,544)	(30,147)
Equity based compensation	18,785	14,100	9,729
Settlement of derivative contracts	0	(15,695)	0
Loss on early extinguishment of debt	0	2,157	552
Increase (decrease) in cash flows due to changes in operating assets and liabilities:
Security deposits	10,717	(97)	(1,707)
Tenant and other receivables	(1,275)	(5,787)	(3,760)
Deferred leasing costs	(26,899)	(31,743)	(22,622)
Prepaid expenses and other assets	(781)	(7,893)	(3,289)
Accounts payable and accrued expenses	1,993	(25,103)	2,939
Deferred revenue and other liabilities	3,902	8,695	824
Net cash provided by operating activities	279,022	194,202	214,755
Cash Flows From Investing Activities
Short-term investments	(400,000)	0	0
Additions to building and improvements	(243,022)	(222,979)	(181,923)
Development costs	(1)	(34)	(453)
Net cash used in investing activities	(643,023)	(223,013)	(182,376)
Cash Flows From Financing Activities
Proceeds from unsecured revolving credit facility	0	0	50,000
Repayments of unsecured revolving credit facility	0	0	(90,000)
Proceeds from mortgage notes payable	160,000	315,000	50,000
Repayment of mortgage notes payable	(266,613)	(346,615)	(32,305)
Proceeds from senior unsecured notes	335,000	115,000	0
Repayment of unsecured term loan	0	(265,000)	0
Proceeds from unsecured revolving credit and term loan facility	0	265,000	0
Deferred financing costs	(1,980)	(13,299)	(3,006)
Net proceeds from the sale of common stock	4,749	0	611,206
Private perpetual preferred unit distributions	(936)	(936)	(936)
Dividends paid to common stockholders	(70,854)	(66,789)	(55,812)
Distributions paid to noncontrolling interests in the operating partnership	(54,749)	(59,238)	(58,206)
Net cash provided by (used in) financing activities	104,617	(56,877)	470,941
Net (decrease) in cash and cash equivalents and restricted cash	(259,384)	(85,688)	503,320
Cash and cash equivalents and restricted cash—beginning of period	530,197	615,885	112,565
Cash and cash equivalents and restricted cash—end of period	270,813	530,197	615,885
Reconciliation of Cash and Cash Equivalents and Restricted Cash:
Cash and cash equivalents at beginning of period	464,344	554,371	46,685
Restricted cash at beginning of period	65,853	61,514	65,880
Cash and cash equivalents and restricted cash—end of period	204,981	464,344	554,371
Restricted cash at end of period	65,832	65,853	61,514
Cash and cash equivalents and restricted cash	530,197	615,885	112,565
Supplemental disclosures of cash flow information:
Cash paid for interest	74,160	66,911	69,062
Interest capitalized	1,596	459	0
Cash paid for income taxes	4,847	5,783	6,238
Non-cash investing and financing activities:
Building and improvements included in accounts payable and accrued expenses	85,242	71,769	66,620
Write-off of fully depreciated assets	39,665	19,136	15,381
Conversion of operating partnership units and Class B shares to Class A shares	$ 70,779	$ 23,435	$ 23,678

Description of Business and Org

Description of Business and Organization	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Organization	Description of Business and Organization As used in these consolidated financial statements, unless the context otherwise requires, “we,” “us,” "our," the "company,” and "ESRT" mean Empire State Realty Trust, Inc. and its consolidated subsidiaries. We are a self-administered and self-managed real estate investment trust, or REIT, that owns, manages, operates, acquires and repositions office and retail properties in Manhattan and the greater New York metropolitan area. We were organized as a Maryland corporation on July 29, 2011. As of December 31, 2018 , our total portfolio contained 10.1 million rentable square feet of office and retail space. We owned 14 office properties (including three long-term ground leasehold interest) encompassing approximately 9.4 million rentable square feet of office space. Nine of these properties are located in the midtown Manhattan market and encompass in the aggregate approximately 7.6 million rentable square feet of office space, including the Empire State Building. Our Manhattan office properties also contain an aggregate of 513,606 rentable square feet of premier retail space on their ground floor and/or lower levels. Our remaining five office properties are located in Fairfield County, Connecticut and Westchester County, New York, encompassing in the aggregate approximately 1.8 million rentable square feet. The majority of square footage for these five properties is located in densely populated metropolitan communities with immediate access to mass transportation. Additionally, we have entitled land at the Stamford Transportation Center in Stamford, Connecticut, adjacent to one of our office properties, that will support the development of an approximately 380,000 rentable square foot office building and garage, which we refer to herein as Metro Tower. As of December 31, 2018 , our portfolio also included four standalone retail properties located in Manhattan and two standalone retail properties located in the city center of Westport, Connecticut, encompassing 205,748 rentable square feet in the aggregate. Empire State Realty OP, L.P. (the "operating partnership") holds substantially all of our assets and conducts substantially all of our business. As of December 31, 2018 , we owned approximately 57.7% of the aggregate operating partnership units in our operating partnership. We, as the sole general partner in our operating partnership, have responsibility and discretion in the management and control of our operating partnership, and the limited partners in our operating partnership, in such capacity, have no authority to transact business for, or participate in the management activities of our operating partnership. Accordingly, our operating partnership has been consolidated by us. We elected to be taxed as a REIT and operate in a manner that we believe allows us to qualify as a REIT for federal income tax purposes commencing with our taxable year ended December 31, 2013. We have two entities that elected to be treated as taxable REIT subsidiaries, or TRSs, and are owned by our operating partnership. The TRSs, through several wholly owned limited liability companies, conduct third-party services businesses, which include the Empire State Building Observatory, cleaning services, cafeteria, restaurant and health clubs, and asset and property management services.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation and Principles of Consolidation The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”) and with the rules and regulations of the Securities and Exchange Commission (the "SEC") represent our assets and liabilities and operating results. The consolidated financial statements include our accounts and our wholly owned subsidiaries as well as our operating partnership and its subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. We consolidate entities in which we have a controlling financial interest. In determining whether we have a controlling financial interest in a partially owned entity and the requirement to consolidate the accounts of that entity, we consider factors such as ownership interest, board representation, management representation, authority to make decisions, and contractual and substantive participating rights of the partners/members as well as whether the entity is a variable interest entity (“VIE”) and we are the primary beneficiary. The primary beneficiary of a VIE is the entity that has (i) the power to direct the activities that most significantly impact the entity's economic performance and (ii) the obligation to absorb losses of the VIE or the right to receive benefits from the VIE that could be significant to the VIE. The primary beneficiary is required to consolidate the VIE. Our operating partnership, Empire State Realty OP, L.P., is a variable interest entity of our company, Empire State Realty Trust, Inc. As the operating partnership is already consolidated in the financial statements of Empire State Realty Trust, Inc., the identification of this entity as a variable interest entity had no impact on our consolidated financial statements. We will assess the accounting treatment for each investment we may have in the future. This assessment will include a review of each entity’s organizational agreement to determine which party has what rights and whether those rights are protective or participating. For all VIEs, we will review such agreements in order to determine which party has the power to direct the activities that most significantly impact the entity’s economic performance and benefit. In situations where we or our partner could approve, among other things, the annual budget, or leases that cover more than a nominal amount of space relative to the total rentable space at each property, we would not consolidate the investment as we consider these to be substantive participation rights that result in shared power of the activities that would most significantly impact the performance and benefit of such joint venture investment. A non-controlling interest in a consolidated subsidiary is defined as the portion of the equity (net assets) in a subsidiary not attributable, directly or indirectly, to a parent. Non-controlling interests are required to be presented as a separate component of equity in the consolidated balance sheets and in the consolidated statements of income by requiring earnings and other comprehensive income to be attributed to controlling and non-controlling interests. Accounting Estimates The preparation of the consolidated financial statements in accordance with GAAP requires management to use estimates and assumptions that in certain circumstances affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities, and the reported revenues and expenses. Significant items subject to such estimates and assumptions include allocation of the purchase price of acquired real estate properties among tangible and intangible assets, determination of the useful life of real estate properties and other long-lived assets, valuation and impairment analysis of commercial real estate properties and other long-lived assets, estimate of tenant expense reimbursements, estimate of percentage of completion on construction contracts, valuation of the allowance for doubtful accounts, and valuation of derivative instruments, senior unsecured notes, mortgage notes payable, unsecured notes, unsecured revolving credit and term loan facilities, and equity based compensation. These estimates are prepared using management’s best judgment, after considering past, current, and expected events and economic conditions. Actual results could differ from those estimates. Revenue Recognition Rental Revenue Rental revenue includes base rents that each tenant pays in accordance with the terms of its respective lease and is reported on a straight-line basis over the non-cancellable term of the lease which includes the effects of rent steps and rent abatements under the leases. In general, we commence rental revenue recognition when the tenant takes possession of the leased space or controls the physical use of the leased space and the leased space is substantially ready for its intended use. We account for all of our leases as operating leases. Deferred rent receivables, including free rental periods and leasing arrangements allowing for increased base rent payments, are accounted for in a manner that provides an even amount of fixed lease revenues over the respective non-cancellable lease terms. Differences between rental income recognized and amounts due under the respective lease agreements are recognized as an increase or decrease to deferred rent receivables. In addition to base rent, our tenants also generally will pay their pro rata share of increases in real estate taxes and operating expenses for the building over a base year. In some leases, in lieu of paying additional rent based upon increases in building operating expenses, the tenant will pay additional rent based upon increases in an index such as the Consumer Price Index over the index value in effect during a base year, or contain fixed percentage increases over the base rent to cover escalations. We will recognize rental revenue of acquired in-place above- and below-market leases at their fair values over the terms of the respective leases, including, for below-market leases, fixed option renewal periods, if any. Lease termination fees are recognized when the fees are determinable, tenant vacancy has occurred, collectability is reasonably assured, we have no continuing obligation to provide services to such former tenants and the payment is not subject to any conditions that must be met or waived. Observatory Revenue Revenues from the sale of Observatory tickets are recognized upon admission or ticket expirations. Deferred revenue related to unused and unexpired tickets as of December 31, 2018 and 2017 was $4.1 million and $4.1 million , respectively, and is included in deferred revenue and other liabilities on the consolidated balance sheets. Gains on Sale of Real Estate We record a gain on sale of real estate when title is conveyed to the buyer and we have no substantial economic involvement with the property. If the sales criteria for the full accrual method are not met, we defer some or all of the gain recognition and account for the continued operations of the property by applying the finance, leasing, profit sharing, deposit, installment or cost recovery methods, as appropriate, until the sales criteria are met. Third-Party Management and Other Fees We earn revenue arising from contractual agreements with related party entities for asset and property management services. This revenue is recognized as the related services are performed under the respective agreements in place. Other Revenues and Fees Other revenues and fees includes parking income, percentage rent, legal, tax and insurance settlements, demand response energy use earnings and sales from our restaurant at the Empire State Building. Advertising and Marketing Costs Advertising and marketing costs are expensed as incurred. The expense for the years ended December 31, 2018 , 2017, and 2016 was $8.9 million , $7.6 million and $9.4 million , respectively, and is included within operating expenses in our consolidated statements of income. Real Estate Properties and Related Intangible Assets Land and buildings and improvements are recorded at cost less accumulated depreciation and amortization. The recorded cost includes cost of acquisitions, development and construction and tenant allowances and improvements. Expenditures for ordinary repairs and maintenance are charged to property operating expense as incurred. Significant replacements and betterments which improve or extend the life of the asset are capitalized. Tenant improvements which improve or extend the life of the asset are capitalized. If a tenant vacates its space prior to the contractual termination of its lease, the unamortized balance of any tenant improvements are written off if they are replaced or have no future value. For developed properties, direct and indirect costs that clearly relate to projects under development are capitalized. Costs include construction costs, professional services such as architectural and legal costs, capitalized interest and direct payroll costs. We begin capitalization when the project is probable. The assets relating to the project are stated at cost and are not depreciated. Once construction is completed and the assets are placed in service, the assets are reclassified to the appropriate asset class and depreciated in accordance with the useful lives as indicated below. Capitalization of interest ceases when the asset is ready for its intended use, which is generally near the date that a certificate of occupancy is obtained. Total capitalized interest for the years ended December 31, 2018 and 2017 was $1.6 million and $0.5 million , respectively. There was no capitalized interest for the year ended December 31, 2016. Depreciation and amortization are computed using the straight-line method for financial reporting purposes. Buildings and improvements are depreciated over the shorter of 39 years, the useful life, or the remaining term of any leasehold interest. Tenant improvement costs, which are included in building and improvements in the consolidated balance sheets, are depreciated over the shorter of (i) the related remaining lease term or (ii) the life of the improvement. Corporate equipment, which is included in “Other assets,” is depreciated over three to seven years. Acquisitions of properties are accounted for utilizing the acquisition method and accordingly the purchase cost is allocated to tangible and intangible assets and liabilities based on their fair values. The fair value of tangible assets acquired is determined by valuing the property as if it were vacant, applying methods similar to those used by independent appraisers of income-producing property. The resulting value is then allocated to land, buildings and improvements, and tenant improvements based on our determination of the fair value of these assets. The assumptions used in the allocation of fair values to assets acquired are based on our best estimates at the time of evaluation. Fair value is assigned to above-market and below-market leases based on the difference between (a) the contractual amounts to be paid by the tenant based on the existing lease and (b) our estimate of current market lease rates for the corresponding in-place leases, over the remaining terms of the in-place leases. Capitalized above-market lease amounts are amortized as a decrease to rental revenue over the remaining terms of the respective leases. Capitalized below-market lease amounts are amortized as an increase to rental revenue over the remaining terms of the respective leases. If a tenant vacates its space prior to the contractual termination of the lease and no rental payments are being made on the lease, any unamortized balance of the related intangible will be written off. The aggregate value of other acquired intangible assets consists of acquired ground leases and acquired in-place leases and tenant relationships. The fair value allocated to acquired in-place leases consists of a variety of components including, but not necessarily limited to: (a) the value associated with avoiding the cost of originating the acquired in-place leases (i.e. the market cost to execute a lease, including leasing commissions and legal fees, if any); (b) the value associated with lost revenue related to tenant reimbursable operating costs estimated to be incurred during the assumed lease-up period (i.e. real estate taxes, insurance and other operating expenses); (c) the value associated with lost rental revenue from existing leases during the assumed lease-up period; and (d) the value associated with any other inducements to secure a tenant lease. We assess the potential for impairment of our long-lived assets, including real estate properties, annually or whenever events occur or a change in circumstances indicate that the recorded value might not be fully recoverable. We determine whether impairment in value has occurred by comparing the estimated future undiscounted cash flows expected from the use and eventual disposition of the asset to its carrying value. If the undiscounted cash flows do not exceed the carrying value, the real estate is adjusted to fair value and an impairment loss is recognized. Assets held for sale are recorded at the lower of cost or fair value less costs to sell. We do not believe that the value of any of our properties and intangible assets were impaired during the years ended December 31, 2018, 2017 and 2016. Cash and Cash Equivalents Cash and cash equivalents consist of cash on hand, government money markets, demand deposits with financial institutions and short-term liquid investments with original maturities of three months or less when purchased. Cash and cash equivalents held at major commercial banks may at times exceed the Federal Deposit Insurance Corporation limit. To date, we have not experienced any losses on our invested cash. Restricted Cash Restricted cash consists of amounts held for tenants in accordance with lease agreements such as security deposits and amounts held by lenders and/or escrow agents to provide for future real estate tax expenditures and insurance expenditures, tenant vacancy related costs and debt service obligations. Short-term Investments Short-term investments include time deposits with original maturities of greater than three months and remaining maturities of less than one year. Tenant and Other Receivables Tenant and other receivables, other than deferred rent receivable, are generally expected to be collected within one year. Allowance for Doubtful Accounts We maintain an allowance against tenant and other receivables and deferred rents receivables for future potential tenant credit losses. The credit assessment is based on the estimated accrued rental revenue that is recoverable over the term of the respective lease. The computation of this allowance is based on the tenants’ payment history and current credit status. If our estimate of collectability differs from the cash received, then the timing and amount of our reported revenue could be impacted. Bad debt expense is included in operating expenses on our consolidated statements of income and includes the impact of changes in the allowance for doubtful accounts on our consolidated balance sheets. Deferred Leasing Costs Deferred leasing costs consist of fees and direct costs incurred to initiate and renew leases, are amortized on a straight-line basis over the related lease term and the expense is included in depreciation and amortization in our consolidated statements of income. Upon the early termination of a lease, unamortized deferred leasing costs are charged to expense. Deferred Financing Costs Fees and costs incurred to obtain long-term financing have been deferred and are amortized as a component of interest expense in our consolidated statements of income over the life of the respective long-term financing on the straight-line method which approximates the effective interest method. Unamortized deferred financing costs are expensed when the associated debt is refinanced or repaid before maturity. Costs incurred in seeking debt, which do not close, are expensed in the period in which it is determined that the financing will not close. Equity Method Investments We account for investments under the equity method of accounting where we do not have control but have the ability to exercise significant influence. Under this method, investments are recorded at cost, and the investment accounts are adjusted for our share of the entities’ income or loss and for distributions and contributions. Equity income (loss) is allocated based on the portion of the ownership interest that is controlled by us. The agreements may designate different percentage allocations among investors for profits and losses; however, our recognition of the entity’s income or loss generally follows the entity’s distribution priorities, which may change upon the achievement of certain investment return thresholds. To the extent that we contributed assets to an entity, our investment in the entity is recorded at cost basis in the assets that were contributed to the entity. Upon contributing assets to an entity, we make a judgment as to whether the economic substance of the transaction is a sale. If so, gain or loss is recognized on the portion of the asset to which the other partners in the entity obtain an interest. To the extent that the carrying amount of these investments on our combined balance sheets is different than the basis reflected at the entity level, the basis difference would be amortized over the life of the related asset and included in our share of equity in net income of the entity. On a periodic basis, we assess whether there are any indicators that the carrying value of our investments in entities may be impaired on an other than temporary basis. An investment is impaired only if management’s estimate of the fair value of the investment is less than the carrying value of the investment on an other than temporary basis. To the extent impairment has occurred, the loss shall be measured as the excess of the carrying value of the investment over the fair value of the investment. As of December 31, 2018 and 2017, we had no equity method investments. Goodwill Goodwill is tested annually for impairment and is tested for impairment more frequently if events and circumstances indicate that the asset might be impaired. An impairment loss is recognized to the extent that the carrying amount, including goodwill, exceeds the reporting unit’s fair value and the implied fair value of goodwill is less than the carrying amount of that goodwill. Non-amortizing intangible assets, such as trade names and trademarks, are subject to an annual impairment test based on fair value and amortizing intangible assets are tested whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. Fair Value Fair value is a market-based measurement, not an entity-specific measurement, and should be determined based on the assumptions that market participants would use in pricing the asset or liability. As a basis for considering market participant assumptions in fair value measurements, the Financial Accounting Standards Board ("FASB") guidance establishes a fair value hierarchy that distinguishes between market participant assumptions based on market data obtained from sources independent of the reporting entity (observable inputs that are classified within levels one and two of the hierarchy) and the reporting entity's own assumptions about market participant assumptions (unobservable inputs classified within Level 3 of the hierarchy). The methodologies used for valuing financial instruments have been categorized into three broad levels as follows: Level 1 - Quoted prices in active markets for identical instruments. Level 2 - Valuations based principally on other observable market parameters, including: • Quoted prices in active markets for similar instruments; • Quoted prices in less active or inactive markets for identical or similar instruments; • Other observable inputs (such as risk free interest rates, yield curves, volatilities, prepayment speeds, loss severities, credit risks and default rates); and • Market corroborated inputs (derived principally from or corroborated by observable market data). Level 3 - Valuations based significantly on unobservable inputs, including: • Valuations based on third-party indications (broker quotes or counterparty quotes) which were, in turn, based significantly on unobservable inputs or were otherwise not supportable; and • Valuations based on internal models with significant unobservable inputs. These levels form a hierarchy. We follow this hierarchy for our financial instruments measured or disclosed at fair value on a recurring and nonrecurring basis and other required fair value disclosures. The classifications are based on the lowest level of input that is significant to the fair value measurement. We use the following methods and assumptions in estimating fair value disclosures for financial instruments. Cash and cash equivalents, restricted cash, short term investments, tenant and other receivables, prepaid expenses and other assets, deferred revenue, tenant security deposits, accounts payable and accrued expenses carrying values approximate their fair values due to the short term maturity of these instruments. The fair value of our senior unsecured notes - exchangeable was derived from quoted prices in active markets and is classified as Level 2 since trading volumes are low. The fair value of derivative instruments is determined using widely accepted valuation techniques, including discounted cash flow analysis on the expected cash flows of each derivative. Although the majority of the inputs used to value our derivatives fall within Level 2 of the fair value hierarchy, the credit valuation adjustments associated with our derivatives utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default by ourselves and our counterparties. The impact of such credit valuation adjustments, determined based on the fair value of each individual contract, was not significant to the overall valuation. As a result, all of our derivatives were classified as Level 2 of the fair value hierarchy. The fair value of our mortgage notes payable, unsecured revolving credit and term loan facility, and senior unsecured notes - Series A, B, C, D, E and F which are determined using Level 3 inputs, are estimated by discounting the future cash flows using current interest rates at which similar borrowings could be made to us. Derivative Instruments We are exposed to the effect of interest rate changes and manage these risks by following policies and procedures including the use of derivatives. To manage exposure to interest rates, derivatives are used primarily to fix the rate on debt based on floating-rate indices. We also hedge exposure to the variability in future cash flows for forecast transactions over a maximum period of 11 months (excluding forecast transactions related to the payment of variable interest on existing financial instruments). We record all derivatives on the balance sheet at fair value. We incorporate credit valuation adjustments to appropriately reflect both our own nonperformance risk and the respective counterparty’s nonperformance risk in the fair value measurements. We measure the credit risk of our derivative instruments that are subject to master netting agreements on a net basis by counterparty portfolio. For derivatives that qualify as cash flow hedges, we report the gain or loss on the derivative designated as a hedge as part of other comprehensive income (loss) and subsequently reclassify the gain or loss into income in the period that the hedged transaction affects income. Income Taxes We elected to be taxed as a REIT under sections 856 through 860 of the Internal Revenue Code of 1986, as amended, (the "Code"), commencing with the taxable year ended December 31, 2013 and believe we qualify as a REIT at December 31, 2018. REITs are subject to a number of organizational and operational requirements, including a requirement that 90% of ordinary “REIT taxable income” (as determined without regard to the dividends paid deduction or net capital gains) be distributed. As a REIT, we will generally not be subject to U.S. federal income tax to the extent that we meet the organizational and operational requirements and our distributions equal or exceed REIT taxable income. For all periods subsequent to the effective date of our REIT election, we have met the organizational and operational requirements and distributions have exceeded net taxable income. Accordingly, no provision has been made for federal and state income taxes. We have elected to treat ESRT Observatory TRS, L.L.C., our subsidiary which holds our observatory operations, and ESRT Holdings TRS, L.L.C., our subsidiary that holds our third party management, restaurant, cafeteria, health clubs and certain cleaning operations, as taxable REIT subsidiaries. Taxable REIT subsidiaries may participate in non-real estate activities and/or perform non-customary services for tenants and their operations are generally subject to regular corporate income taxes. Our taxable REIT subsidiaries accounts for its income taxes in accordance with GAAP, which includes an estimate of the amount of taxes payable or refundable for the current year and deferred tax liabilities and assets for the future tax consequences of events that have been recognized in our financial statements or tax returns. The calculation of the taxable REIT subsidiaries' tax provisions may require interpreting tax laws and regulations and could result in the use of judgments or estimates which could cause its recorded tax liability to differ from the actual amount due. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The taxable REIT subsidiaries periodically assess the realizability of deferred tax assets and the adequacy of deferred tax liabilities, including the results of local, state, or federal statutory tax audits or estimates and judgments used. We apply provisions for measuring and recognizing tax benefits associated with uncertain income tax positions. Penalties and interest, if incurred, would be recorded as a component of income tax expense. As of December 31, 2018 and 2017, we do not have a liability for uncertain tax positions. As of December 31, 2018 , the tax years ended December 31, 2015 through December 31, 2018 remain open for an audit by the Internal Revenue Service, state or local authorities. Share-Based Compensation Share-based compensation is measured at the fair value of the award on the date of grant and recognized as an expense on a straight-line basis over the vesting period. The determination of fair value of these awards is subjective and involves significant estimates and assumptions including expected volatility of our stock, expected dividend yield, expected term, and assumptions of whether these awards will achieve parity with other operating partnership units or achieve performance thresholds. We believe that the assumptions and estimates utilized are appropriate based on the information available to management at the time of grant. Per Share Data Basic and diluted earnings per share are computed based upon the weighted average number of shares outstanding during the respective period. Segment Reporting We have identified two reportable segments: (1) Real Estate and (2) Observatory. Our real estate segment includes all activities related to the ownership, management, operation, acquisition, repositioning and disposition of our real estate assets. Our observatory segment operates the 86th and 102nd floor observatories at the Empire State Building. These two lines of businesses are managed separately because each business requires different support infrastructures, provides different services and has dissimilar economic characteristics such as investments needed, stream of revenues and different marketing strategies. We account for intersegment sales and rent as if the sales or rent were to third parties, that is, at current market prices. Reclassification Certain prior year balances have been reclassified to conform to our current year presentation. The 2017 and 2016 balance of other revenues and fees has been reclassified to separately present lease termination fees and interest income and conform to our current year presentation. Recently Issued or Adopted Accounting Standards During August 2018, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (a consensus of the FASB Emerging Issues Task Force), which contain amendments that align the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal use software license). Accordingly, for entities in a hosting arrangement that is a service contract, costs for implementation activities in the application development stage are capitalized depending on the nature of the costs, while costs incurred during the preliminary project and post-implementation stages are expensed as the activities are performed. The amendments in ASU No. 2018-15 also require the entity (customer) to expense the capitalized implementation costs of a hosting arrangement that is a service contract over the term of the hosting arrangement. The amendments are effective for public business entities for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Early adoption of the amendments is permitted, including adoption in any interim period. The amendments in ASU No. 2018-15 should be applied either retrospectively or prospectively to all implementation costs incurred after the date of adoption. We are evaluating the impact of adopting this new accounting standard on our consolidated financial statements. During January 2017, the FASB issued ASU No. 2017-04, Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment, which contain amendments that modify the concept of impairment from the condition that exists when the carrying amount of goodwill exceeds its implied fair value to the condition that exists when the carrying amount of a reporting unit exceeds its fair value. An entity no longer will determine goodwill impairment by calculating the implied fair value of goodwill by assigning the fair value of a reporting unit to all of its assets and liabilities as if that reporting unit had been acquired in a business combination. Because these amendments eliminate Step 2 from the goodwill impairment test, they should reduce the cost and complexity of evaluating goodwill for impairment. ASU No. 2017-04 should be applied on a prospective basis and the amendments adopted for the annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. We are evaluating the impact of adopting this new accounting standard on our consolidated financial statements. During January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business, which contain amendments to clarify the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The amendments in ASU No. 2017-01 provide a screen to determine when an integrated set of assets and activities (collectively referred to as a “set”) is not a business. The screen requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a

Deferred Costs, Acquired Lease

Deferred Costs, Acquired Lease Intangibles and Goodwill	12 Months Ended
	Dec. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Deferred Costs, Acquired Lease Intangibles and Goodwill	Deferred Costs, Acquired Lease Intangibles and Goodwill Deferred costs, net, consisted of the following at December 31, 2018 and 2017 (amounts in thousands): 2018 2017 Leasing costs $ 178,120 $ 164,751 Acquired in-place lease value and deferred leasing costs 214,550 237,364 Acquired above-market leases 52,136 67,415 444,806 469,530 Less: accumulated amortization (209,839 ) (215,102 ) Total deferred costs, net, excluding net deferred financing costs $ 234,967 $ 254,428 At December 31, 2018 and 2017, $6.3 million and $8.3 million , respectively, of net deferred financing costs associated with the unsecured revolving credit facility was included in deferred costs, net on the consolidated balance sheets. Amortization expense related to deferred leasing and acquired deferred leasing costs was $26.3 million , $24.1 million , and $24.2 million , for the years ended December 31, 2018 , 2017, and 2016, respectively. Amortization expense related to acquired lease intangibles was $12.1 million , $17.1 million and $24.6 million for the years ended December 31, 2018 , 2017 and 2016, respectively. Amortizing acquired intangible assets and liabilities consisted of the following at December 31, 2018 and 2017 (amounts in thousands): 2018 2017 Acquired below-market ground leases $ 396,916 $ 396,916 Less: accumulated amortization (36,518 ) (28,687 ) Acquired below-market ground leases, net $ 360,398 $ 368,229 2018 2017 Acquired below-market leases $ (118,462 ) $ (132,026 ) Less: accumulated amortization 66,012 65,979 Acquired below-market leases, net $ (52,450 ) $ (66,047 ) Rental revenue related to the amortization of below market leases, net of above market leases was $6.1 million , $5.7 million and $8.8 million for the years ended December 31, 2018 , 2017 and 2016, respectively. The remaining weighted-average amortization period as of December 31, 2018 is 24.5 years, 4.5 years, 3.8 years and 4.0 years for below-market ground leases, in-place leases and deferred leasing costs, above-market leases and below-market leases, respectively. We expect to recognize amortization expense and rental revenue from the acquired intangible assets and liabilities as follows (amounts in thousands): For the year ending: Future Ground Rent Amortization Future Amortization Expense Future Rental Revenue 2019 $ 7,831 $ 15,829 $ 6,875 2020 7,831 12,967 3,651 2021 7,831 11,250 2,868 2022 7,831 10,433 3,185 2023 7,831 9,756 3,181 Thereafter 321,243 31,690 9,532 $ 360,398 $ 91,925 $ 29,292 As of December 31, 2018 , we had goodwill of $491.5 million . In 2013, we acquired the interests in Empire State Building Company, L.L.C. and 501 Seventh Avenue Associates, L.L.C. for an amount in excess of their net tangible and identified intangible assets and liabilities and as a result we recorded goodwill related to the transaction. Goodwill was allocated $227.5 million to the observatory operations of the Empire State Building, $250.8 million to Empire State Building, and $13.2 million to 501 Seventh Avenue. We performed an annual review of goodwill for impairment and concluded there was no impairment of goodwill. Our methodology to review goodwill impairment, which includes a significant amount of judgment and estimates, provides a reasonable basis to determine whether impairment has occurred. However, many of the factors employed in determining whether or not goodwill is impaired are outside of our control and it is reasonably likely that assumptions and estimates will change in future periods.

Debt

Debt	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Debt	Debt Debt consisted of the following as of December 31, 2018 and 2017 (amounts in thousands): As of December 31, 2018 Principal Balance as Principal Balance as Stated Effective (1) Maturity (2) Fixed rate mortgage debt Metro Center $ 91,838 $ 93,948 3.59 % 3.68 % 11/5/2024 10 Union Square 50,000 50,000 3.70 % 3.97 % 4/1/2026 1542 Third Avenue 30,000 30,000 4.29 % 4.53 % 5/1/2027 First Stamford Place (3) 180,000 180,000 4.28 % 4.45 % 7/1/2027 1010 Third Avenue and 77 West 55th Street 38,995 39,710 4.01 % 4.22 % 1/5/2028 10 Bank Street 33,779 34,602 4.23 % 4.35 % 6/1/2032 383 Main Avenue 30,000 30,000 4.44 % 4.55 % 6/30/2032 1333 Broadway 160,000 66,602 4.21 % 4.29 % 2/5/2033 1400 Broadway (first lien mortgage loan) — 66,632 — — — (second lien mortgage loan) — 9,172 — — — 111 West 33rd Street (first lien mortgage loan) — 74,045 — — — (second lien mortgage loan) — 9,369 — — — 1350 Broadway — 37,144 — — — Total mortgage debt 614,612 721,224 Senior unsecured notes - exchangeable 250,000 250,000 2.63 % 3.93 % 8/15/2019 Senior unsecured notes: (4) Series A 100,000 100,000 3.93 % 3.96 % 3/27/2025 Series B 125,000 125,000 4.09 % 4.12 % 3/27/2027 Series C 125,000 125,000 4.18 % 4.21 % 3/27/2030 Series D 115,000 115,000 4.08 % 4.11 % 1/22/2028 Series E 160,000 — 4.26 % 4.27 % 3/22/2030 Series F 175,000 — 4.44 % 4.45 % 3/22/2033 Unsecured revolving credit facility (4) — — (5) (5) 8/29/2021 Unsecured term loan facility (4) 265,000 265,000 (6) (6) 8/29/2022 Total principal 1,929,612 1,701,224 Unamortized (discount) premiums, net of unamortized premiums (discount) (1,647 ) (3,370 ) Deferred financing costs, net (9,032 ) (9,133 ) Total $ 1,918,933 $ 1,688,721 ______________ (1) The effective rate is the yield as of December 31, 2018, including the effects of debt issuance costs and the amortization of the fair value of debt adjustment. (2) Pre-payment is generally allowed for each loan upon payment of a customary pre-payment penalty. (3) Represents a $164 million mortgage loan bearing interest of 4.09% and a $16 million loan bearing interest at 6.25% . (4) At December 31, 2018, we were in compliance with all debt covenants. (5) At December 31, 2018, the unsecured revolving credit facility bears a floating rate at 30 day LIBOR plus 1.10% . The rate at December 31, 2018 was 3.60% . (6) The unsecured term loan facility bears a floating rate at 30 day LIBOR plus 1.20% . Pursuant to an interest rate swap agreement, the LIBOR rate is fixed at 2.1485% through maturity. The rate at December 31, 2018 was 3.35% . Mortgage Debt During January 2018, we refinanced and increased our mortgage debt on 1333 Broadway from $66.6 million to $160.0 million . A portion of this increase was applied to release the $75.8 million mortgage lien on 1400 Broadway. During March 2018, we repaid our mortgage indebtedness on 111 West 33rd Street and 1350 Broadway. Principal Payments Aggregate required principal payments at December 31, 2018 are as follows (amounts in thousands): Year Amortization Maturities Total 2019 $ 3,790 $ 250,000 $ 253,790 2020 3,938 — 3,938 2021 4,090 — 4,090 2022 5,628 265,000 270,628 2023 7,876 — 7,876 Thereafter 33,868 1,355,422 1,389,290 Total principal maturities $ 59,190 $ 1,870,422 $ 1,929,612 Deferred Financing Costs Deferred financing costs, net, consisted of the following at December 31, 2018 and 2017 (amounts in thousands): 2018 2017 Financing costs $ 25,315 $ 24,446 Less: accumulated amortization (10,027 ) (7,039 ) Total deferred financing costs, net $ 15,288 $ 17,407 At December 31, 2018 and 2017, $6.3 million and $8.3 million , respectively, of net deferred financing costs associated with the unsecured revolving credit facility were included in deferred costs, net on the consolidated balance sheet. Amortization expense related to deferred financing costs was $4.1 million , $4.7 million , and $5.0 million , for the years ended December 31, 2018 , 2017 and 2016, respectively, and was included in interest expense. Unsecured Revolving Credit and Term Loan Facility During August 2017, through the Operating Partnership, we entered into an amended and restated senior unsecured revolving credit and term loan facility (the “Facility”) with Bank of America, N.A., as administrative agent, Merrill Lynch, Pierce, Fenner & Smith Incorporated and Wells Fargo Securities, LLC as Joint Lead Arrangers and Joint Bookrunners, Wells Fargo, National Association and Capital One, National Association, as co-syndication agents, and the lenders party thereto. The Facility amended and restated the credit facility dated as of January 23, 2015, with Bank of America, N.A., Merrill Lynch, Goldman Sachs and the other lenders party thereto. In connection with the modification of the credit facility and term loan, we incurred a loss on early extinguishment of debt of $2.2 million which is reflected in our consolidated statement of income for the year ended December 31, 2017. This transaction extended the unsecured revolving credit and term loan facility maturity, lowered borrowing costs and added flexibility to the financial covenants. The Facility is in the original principal amount of up to $1.365 billion which consists of a $1.1 billion revolving credit facility and a $265.0 million term loan facility. The new revolving credit facility replaced a credit facility which was due to mature in January 2019 and was undrawn when amended. The term loan facility was borrowed in full at closing and used to repay a $265.0 million term loan that had been due in 2022. We may request the Facility be increased through one or more increases in the revolving credit facility or one or more increases in the term loan facility or the addition of new pari passu term loan tranches, for a maximum aggregate principal amount not to exceed $1.75 billion. The initial maturity of the unsecured revolving credit facility is August 2021. We have the option to extend the initial term for up to two additional 6 -month periods, subject to certain conditions, including the payment of an extension fee equal to 0.0625% and 0.075% of the then outstanding commitments under the unsecured revolving credit facility on the first and the second extensions, respectively. The term loan facility matures on August 2022. We may prepay the loans under the Facility at any time, subject to reimbursement of the lenders’ breakage and redeployment costs in the case of prepayment of Eurodollar Rate borrowings. The Facility includes the following financial covenants: (i) maximum leverage ratio of total indebtedness to total asset value (as defined in the agreement) of the loan parties and their consolidated subsidiaries will not exceed 60% , (ii) consolidated secured indebtedness will not exceed 40% of total asset value, (iii) tangible net worth will not be less than $1.2 billion plus 75% of net equity proceeds received by the Operating Partnership (other than proceeds received within ninety (90) days after the redemption, retirement or repurchase of ownership or equity interests in us up to the amount paid by us in connection with such redemption, retirement or repurchase, where, the net effect is that the Operating Partnership shall not have increased its net worth as a result of any such proceeds), (iv) adjusted EBITDA (as defined in the Facility) to consolidated fixed charges will not be less than 1.50 x, (v) the aggregate net operating income with respect to all unencumbered eligible properties to the portion of interest expense attributable to unsecured indebtedness will not be less than 1.75 x, and (vi) the ratio of total unsecured indebtedness to unencumbered asset value will not exceed 60% . The Facility contains customary covenants, including limitations on liens, investment, distributions, debt, fundamental changes, and transactions with affiliates, and requires certain customary financial reports. The Facility contains customary events of default (subject in certain cases to specified cure periods), including but not limited to non-payment, breach of covenants, representations or warranties, cross defaults, bankruptcy or other insolvency events, judgments, ERISA events, invalidity of loan documents, loss of real estate investment trust qualification, and occurrence of a change of control (defined in the agreement for the Facility). As of December 31, 2018 , we were in compliance with the covenants under the Facility. Senior Unsecured Notes Exchangeable During August 2014, we issued $250.0 million principal amount of 2.625% Exchangeable Senior Notes (“ 2.625% Exchangeable Senior Notes”) due August 15, 2019. Interest on the 2.625% Exchangeable Senior Notes is payable semi-annually in arrears on February 15 and August 15 of each year. The 2.625% Exchangeable Senior Notes are senior unsecured obligations and rank equally in right of payment with all of our other senior unsecured indebtedness and effectively subordinated in right of payment to all of our secured indebtedness (to the extent of the value of the collateral securing such indebtedness) and structurally subordinated to all liabilities and preferred equity of our subsidiaries. The 2.625% Exchangeable Senior Notes will mature on August 15, 2019, unless earlier exchanged, redeemed or repurchased. Holders may exchange their 2.625% Exchangeable Senior Notes at their option at any time prior to the close of business on the business day immediately preceding May 15, 2019 only under the following circumstances: (i) during any calendar quarter beginning after September 30, 2014 (and only during such quarter) if the closing sale price of our Class A common stock is more than 130% of the then current exchange price for at least 20 trading days (whether or not consecutive) in the period of the 30 consecutive trading days ending on the last trading day of the previous calendar quarter; (ii) during the five consecutive business-day period following any five consecutive trading-day period in which the trading price per 1,000 principal amount of the 2.625% Exchangeable Senior Notes for each trading day during such five consecutive trading-day period in which the trading price per 1,000 principal amount of the 2.625% Exchangeable Senior Notes for each trading day during such five trading-day period was less than 98% of the closing sale price of our Class A common stock, for each trading day during such five trading-day period multiplied by the then current exchange rate; (iii) if we call any or all of the 2.625% Exchangeable Senior Notes for redemption, at any time prior to the close of business on the scheduled trading day immediately preceding the redemption date; or (iv) upon the occurrence of specified corporate transactions (significant consolidation, sale, merger, share exchange, fundamental change, etc.). On or after May 15, 2019, and on or prior to the second scheduled trading day immediately preceding the maturity date, holders may exchange their notes without regard to the foregoing conditions. The 2.625% Exchangeable Senior Notes will be exchangeable into cash, shares of Class A common stock or a combination of cash and shares of Class A common stock, at our election. We have asserted it is our intent and ability to settle the principal amount of the 2.625% Exchangeable Senior Notes in cash. The initial exchange rate of 2.625% Exchangeable Senior Notes is 51.4059 shares per $1,000 principal amount of notes (equivalent to an initial exchange price of approximately $19.45 per share of Class A common stock), subject to adjustment, as described in the related indenture governing the 2.625% Exchangeable Senior Notes. As of December 31, 2018 , the exchange rate of the 2.625% Exchangeable Senior Notes was 52.0116 shares per $1,000 principal amount of notes (equivalent to an initial exchange price of approximately $19.23 per share of Class A common stock), subject to adjustment, as described in the related indenture governing the 2.625% Exchangeable Senior Notes. Following certain corporate transactions which constitute a make-whole fundamental change (defined in the indenture), we will increase the exchange rate for holders who elect to exchange their 2.625% Exchangeable Senior Notes in connection with such make whole fundamental change in certain circumstances. Following certain corporate transactions which constitute a fundamental change, holders may require us to repurchase the 2.625% Exchangeable Senior Notes for cash at a price equal to 100% of the principal amount of the notes to be purchased plus any accrued and unpaid interest to, but excluding, the repurchase date. We have separately accounted for the liability and equity components of the 2.625% Exchangeable Senior Notes by bifurcating gross proceeds between the indebtedness, or liability component, and the embedded conversion option, or the equity component. The bifurcation was done by estimating an effective interest rate as of the date of the issuance for similar notes which do not contain an embedded conversion option. This effective interest rate was estimated to be 3.8% and was used to compute the fair value at the time of issuance for the indebtedness of $236.6 million . The gross proceeds from the issuance of the 2.625% Exchangeable Senior Notes less the initial amount allocated to the indebtedness resulted in a $13.4 million allocation to the embedded conversion option which is included in Equity, net of financing costs, in the consolidated balance sheets as of December 31, 2018 and 2017. The resulting debt discount is being amortized over the five year period in which the 2.625% Exchangeable Senior Notes are expected to be outstanding (that is, through maturity date) as additional non-cash interest expense. As of December 31, 2018 and 2017, the unamortized discount was $1.6 million and $4.3 million , respectively. Underwriting discounts and commissions and issuance costs totaled $3.1 million and were allocated to the indebtedness and the embedded conversion option on a pro-rata basis and accounted for as debt issuance costs and equity issuance costs, respectively. In this connection, $2.9 million attributable to the indebtedness was recorded as part of deferred costs, to be subsequently amortized using the effective interest method as interest expense over the expected term of the 2.625% Exchangeable Senior Notes, and $0.2 million attributable to the embedded conversion option was recorded as a reduction to Equity in the consolidated balance sheets as of December 31, 2018 and 2017. For the years ended December 31, 2018 , 2017 and 2016, total interest expense related to the 2.625% Exchangeable Senior Notes was $9.9 million , $9.9 million and $9.9 million , respectively, consisting of (i) contractual interest expense of $6.6 million , $6.6 million and $6.6 million , respectively, (ii) additional non-cash interest expense of $2.7 million , $2.7 million and $2.7 million , respectively, related to the accretion of the debt discount, and (iii) amortization of deferred financing costs of $0.6 million , $0.6 million and $0.6 million , respectively. Senior Unsecured Notes During December 2017, we entered into an agreement to issue and sell an aggregate principal amount of $450.0 million of senior unsecured notes consisting of $115.0 million of 4.08% Series D Senior Notes due 2028, $160.0 million of 4.26% Series E Senior Notes due 2030, and $175.0 million of 4.44% Series F Senior Notes due 2033. We issued and sold the Series D Senior Notes in December 2017 and the Series E and F Senior Notes in March 2018. In connection with the March 2018 issuance of the notes, we repaid our mortgage indebtedness on 111 West 33rd Street and 1350 Broadway. The terms of the Series A, B, C, D, E, and F senior notes agreements include customary covenants, including limitations on liens, investment, distributions, debt, fundamental changes, and transactions with affiliates and require certain customary financial reports. It also requires compliance with financial ratios including a maximum leverage ratio, a maximum secured leverage ratio, a minimum amount of tangible net worth, a minimum fixed charge coverage ratio, a minimum unencumbered interest coverage ratio, and a maximum unsecured leverage ratio. As of December 31, 2018 , we were in compliance with the covenants under the outstanding Senior Unsecured Notes.

Accounts Payable and Accrued Ex

Accounts Payable and Accrued Expenses	12 Months Ended
	Dec. 31, 2018
Payables and Accruals [Abstract]
Accounts Payable and Accrued Expenses	Accounts Payable and Accrued Expenses Accounts payable and accrued expenses consist of the following as of December 31, 2018 and 2017 (amounts in thousands): 2018 2017 Accrued capital expenditures $ 85,242 $ 71,769 Accounts payable and accrued expenses 34,585 32,509 Interest rate swap agreements liability 5,243 436 Accrued interest payable 4,990 5,687 Due to affiliated companies 616 448 Total accounts payable and accrued expenses $ 130,676 $ 110,849

Financial Instruments and Fair

Financial Instruments and Fair Values	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Financial Instruments and Fair Values	Financial Instruments and Fair Values Derivative Financial Instruments We use derivative financial instruments primarily to manage interest rate risk and such derivatives are not considered speculative. These derivative instruments are typically in the form of interest rate swap and forward agreements and the primary objective is to minimize interest rate risks associated with investing and financing activities. The counterparties of these arrangements are major financial institutions with which we may also have other financial relationships. We are exposed to credit risk in the event of non-performance by these counterparties; however, we currently do not anticipate that any of the counterparties will fail to meet their obligations. We have agreements with our derivative counterparties that contain a provision where if we either default or are capable of being declared in default on any of our indebtedness, then we could also be declared in default on our derivative obligations. As of December 31, 2018, the fair value of derivatives in a net liability position, which includes accrued interest but excludes any adjustment for nonperformance risk, related to these agreements was $5.3 million . If we had breached any of these provisions at December 31, 2018, we could have been required to settle our obligations under the agreements at their termination value of $5.3 million . As of December 31, 2018 and 2017, we had interest rate LIBOR swaps with an aggregate notional value of $515.0 million and $265.0 million , respectively, which were designated as cash flow hedges of interest rate risk. We are hedging variability in future cash flows associated with our existing variable-rate term loan facility and with a forecasted refinancing of our exchangeable senior notes. The notional value does not represent exposure to credit, interest rate or market risks. As of December 31, 2018 , the fair value of these derivative instruments amounted to $2.5 million which is included in prepaid expenses and other assets and ( $5.2 million ) which is included in accounts payable and accrued expenses on the consolidated balance sheet. As of December 31, 2017, the fair value of the derivative instrument amounted to ( $0.4 million ) which is included in accounts payable and accrued expenses on the consolidated balance sheet. As of December 31, 2018 and 2017, a net unrealized loss of $0.9 million and $10.5 million , respectively, is reflected in the consolidated statements of comprehensive income (loss) relating to both active and terminated cash flow hedges of interest rate risk. Amounts reported in accumulated other comprehensive income (loss) related to derivatives will be reclassified to interest expense as interest payments are made on the debt. We estimate that $0.9 million net loss of the current balance held in accumulated other comprehensive loss will be reclassified into interest expense within the next 12 months. For the year ended December 31, 2017, we recognized a loss of $0.3 million from derivative financial instruments, incurred in connection with the partial termination and re-designation of related cash flow hedges. The table below summarizes the terms of agreements and the fair values of our derivative financial instruments as of December 31, 2018 and 2017 (dollar amounts in thousands): December 31, 2018 December 31, 2017 Derivative Notional Amount Receive Rate Pay Rate Effective Date Expiration Date Asset Liability Asset Liability Interest rate swap $ 265,000 1 Month LIBOR 2.1485 % August 31, 2017 August 24, 2022 $ 2,536 $ — $ — $ (436 ) Interest rate swap 125,000 3 Month LIBOR 2.9580 % July 1, 2019 July 1, 2026 — (2,623 ) — — Interest rate swap 125,000 3 Month LIBOR 2.9580 % July 1, 2019 July 1, 2026 — (2,620 ) — — $ 2,536 $ (5,243 ) $ — $ (436 ) The table below shows the effect of our derivative financial instruments designated as cash flow hedges on accumulated other comprehensive income (loss) for the years ended December 31, 2018, 2017 and 2016 (amounts in thousands): Effects of Cash Flow Hedges December 31, 2018 December 31, 2017 December 31, 2016 Amount of gain (loss) recognized in other comprehensive income (loss) $ (2,721 ) $ (11,658 ) $ (3,054 ) Amount of gain (loss) reclassified from accumulated other comprehensive income (loss) into interest expense (1,845 ) (1,142 ) — The table below shows the effect of our derivative financial instruments designated as cash flow hedges on the consolidated statements of income for the years ended December 31, 2018, 2017 and 2016 (amounts in thousands): Effects of Cash Flow Hedges December 31, 2018 December 31, 2017 December 31, 2016 Total interest (expense) presented on the consolidated statements of income in which the effects of cash flow hedges are recorded $ (79,623 ) $ (68,473 ) $ (70,595 ) Amount of gain (loss) reclassified from accumulated other comprehensive income (loss) into interest expense (1,845 ) (1,142 ) — Fair Valuation The estimated fair values at December 31, 2018 and 2017 were determined by management, using available market information and appropriate valuation methodologies. Considerable judgment is necessary to interpret market data and develop estimated fair value. Accordingly, the estimates presented herein are not necessarily indicative of the amounts we could realize on disposition of the financial instruments. The use of different market assumptions and/or estimation methodologies may have a material effect on the estimated fair value amounts. The following tables summarize the carrying and estimated fair values of our financial instruments as of December 31, 2018 and 2017 (amounts in thousands): December 31, 2018 Carrying Value Estimated Fair Value Total Level 1 Level 2 Level 3 Interest rate swaps included in prepaid expenses and other assets $ 2,536 $ 2,536 $ — $ 2,536 $ — Interest rate swaps included in accounts payable and accrued expenses 5,243 5,243 — 5,243 — Mortgage notes payable 608,567 597,424 — — 597,424 Senior unsecured notes - Exchangeable 247,930 250,625 — 250,625 — Senior unsecured notes - Series A, B, C, D, E and F 798,289 795,662 — — 795,662 Unsecured term loan facility 264,147 265,000 — — 265,000 December 31, 2017 Carrying Value Estimated Fair Value Total Level 1 Level 2 Level 3 Interest rate swaps included in prepaid expenses and other assets $ — $ — $ — $ — $ — Interest rate swaps included in accounts payable and accrued expenses 436 436 — 436 — Mortgage notes payable 717,164 707,300 — — 707,300 Senior unsecured notes - Exchangeable 244,739 275,723 — 275,723 — Senior unsecured notes - Series A, B, C, D, E and F 463,156 460,352 — — 460,352 Unsecured term loan facility 263,662 265,000 — — 265,000 Disclosure about the fair value of financial instruments is based on pertinent information available to us as of December 31, 2018 and 2017 . Although we are not aware of any factors that would significantly affect the reasonable fair value amounts, such amounts have not been comprehensively revalued for purposes of these financial statements since that date and current estimates of fair value may differ significantly from the amounts presented herein.

Rental Income

Rental Income	12 Months Ended
	Dec. 31, 2018
Leases [Abstract]
Rental Income	Rental Income We lease various spaces to tenants over various terms. Certain leases have renewal options for additional terms. The leases provide for base monthly rentals and reimbursements for real estate taxes, escalations linked to the consumer price index or common area maintenance known as operating expense escalation. Operating expense reimbursements are reflected in our consolidated statements of income as tenant expense reimbursement. As of December 31, 2018 , we were entitled to the following future contractual minimum lease payments on non-cancellable operating leases to be received which expire on various dates through 2038 (amounts in thousands): 2019 $ 485,441 2020 460,127 2021 423,365 2022 391,395 2023 362,738 Thereafter 1,536,461 $ 3,659,527 The above future minimum lease payments exclude tenant recoveries, amortization of deferred rent receivables and the net accretion of above-below-market lease intangibles. Some leases are subject to termination options generally upon payment of a termination fee. The preceding table is prepared assuming such options are not exercised.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal Proceedings Litigation Except as described below, as of December 31, 2018 , we were not involved in any material litigation, nor, to our knowledge, was any material litigation threatened against us or our properties, other than routine litigation arising in the ordinary course of business such as disputes with tenants. We believe that the costs and related liabilities, if any, which may result from such actions will not materially affect our condensed consolidated financial position, operating results or liquidity. As previously disclosed, in October 2014, 12 former investors in Empire State Building Associates L.L.C. (“ESBA”), which prior to the initial public offering of our company (the "Offering"), owned the fee title to the Empire State Building, filed an arbitration with the American Arbitration Association against Peter L. Malkin, Anthony E. Malkin, Thomas N. Keltner, Jr., and our subsidiary ESRT MH Holdings LLC, the former supervisor of ESBA, as respondents. The statement of claim (also filed later in federal court in New York for the expressed purpose of tolling the statute of limitations) alleges breach of fiduciary duty and related claims in connection with the Offering and formation transactions and seeks monetary damages and declaratory relief. These investors had opted out of a prior class action bringing similar claims that was settled with court approval. The respondents filed an answer and counterclaims. In March 2015, the federal court action was stayed on consent of all parties pending the arbitration. Arbitration hearings for a select number of sessions started in May 2016 and concluded in August 2018. Post-hearing briefing is currently scheduled to be completed by June 25, 2019. The respondents believe the allegations in the arbitration are entirely without merit, and they intend to continue to defend them vigorously. Pursuant to indemnification agreements which were made with our directors, executive officers and chairman emeritus as part of our formation transactions, Anthony E. Malkin, Peter L. Malkin and Thomas N. Keltner, Jr. have defense and indemnity rights from us with respect to this arbitration. Ground Lease Commitments We make payments under ground leases related to three of our properties. Minimum rent is expensed on a straight-line basis over the non-cancellable term of the leases. The ground leases are due to expire between the years 2050 and 2077. Future minimum lease payments to be paid over the terms of the leases are as follows (amounts in thousands): 2019 $ 1,518 2020 1,518 2021 1,518 2022 1,518 2023 1,518 Thereafter 68,298 Total $ 75,888 Unfunded Capital Expenditures At December 31, 2018 , we estimate that we will incur approximately $88.4 million of capital expenditures (including tenant improvements and leasing commissions) on our properties pursuant to existing lease agreements. We expect to fund these capital expenditures with operating cash flow, additional property level mortgage financings, our unsecured credit facility, cash on hand and other borrowings. Future property acquisitions may require substantial capital investments for refurbishment and leasing costs. We expect that these financing requirements will be met in a similar fashion. Concentration of Credit Risk Financial instruments that subject us to credit risk consist primarily of cash and cash equivalents, restricted cash, short-term investments, tenant and other receivables and deferred rent receivables. At December 31, 2018 , we held on deposit at various major financial institutions cash and cash equivalents, restricted cash balances and short-term investments in excess of amounts insured by the Federal Deposit Insurance Corporation. Real Estate Investments Our properties are located in Manhattan, New York; Fairfield County, Connecticut; and Westchester County, New York. The latter locations are suburbs of the city of New York. The ability of the tenants to honor the terms of their respective leases is dependent upon the economic, regulatory and social factors affecting the markets in which the tenants operate. We perform ongoing credit evaluations of our tenants for potential credit losses. Tenant Credit Evaluations Our investments in real estate properties are subject to risks incidental to the ownership and operation of commercial real estate. These risks include, among others, the risks normally associated with changes in general economic conditions, trends in the real estate industry, creditworthiness of tenants, competition of tenants and customers, changes in tax laws, interest rate levels, the availability and cost of financing, and potential liability under environmental and other laws. We may require tenants to provide some form of credit support such as corporate guarantees and/or other financial guarantees and we perform ongoing credit evaluations of tenants. Although the tenants operate in a variety of industries, to the extent we have a significant concentration of rental revenue from any single tenant, the inability of that tenant to make its lease payments could have an adverse effect on our company. Major Customers and Other Concentrations For the year ended December 31, 2018, other than five tenants who accounted for 6.0% , 3.1% , 2.9% , 2.0% and 2.0% of rental revenues, no other tenant in our portfolio accounted for more than 2.0% of rental revenues. For the year ended December 31, 2017, other than five tenants who accounted for 6.3% , 3.2% , 2.9% , 2.1% and 2.0% of rental revenues, no other tenant in our portfolio accounted for more than 2.0% of rental revenues. For the year ended December 31, 2016, other than five tenants who accounted for 6.4% , 3.3% , 2.9% , 2.3% and 2.0% of rental revenues, no other tenant in our portfolio accounted for more than 2.0% of rental revenues. For the years ended December 31, 2018 , 2017 and 2016, the six properties listed below accounted for the indicated percentage of total rental revenues. No other property accounted for more than 5.0% of total rental revenues. Year Ended December 31, 2018 2017 2016 Empire State Building 31.9 % 32.0 % 32.6 % One Grand Central Place 12.8 % 13.1 % 12.5 % 111 West 33rd Street 9.3 % 8.6 % 6.8 % 1400 Broadway 7.1 % 7.4 % 7.8 % First Stamford Place 5.9 % 5.4 % 6.4 % 250 West 57th Street 5.2 % 5.2 % 5.3 % Asset Retirement Obligations We are required to accrue costs that we are legally obligated to incur on retirement of our properties which result from acquisition, construction, development and/or normal operation of such properties. Retirement includes sale, abandonment or disposal of a property. Under that standard, a conditional asset retirement obligation represents a legal obligation to perform an asset retirement activity in which the timing and/or method of settlement is conditional on a future event that may or may not be within a company’s control and a liability for a conditional asset retirement obligation must be recorded if the fair value of the obligation can be reasonably estimated. Environmental site assessments and investigations have identified asbestos or asbestos-containing building materials in certain of our properties. As of December 31, 2018 , management has no plans to remove or alter these properties in a manner that would trigger federal and other applicable regulations for asbestos removal, and accordingly, the obligations to remove the asbestos or asbestos-containing building materials from these properties have indeterminable settlement dates. As such, we are unable to reasonably estimate the fair value of the associated conditional asset retirement obligation. However ongoing asbestos abatement, maintenance programs and other required documentation are carried out as required and related costs are expensed as incurred. Other Environmental Matters Certain of our properties have been inspected for soil contamination due to pollutants, which may have occurred prior to our ownership of these properties or subsequently in connection with its development and/or its use. Required remediation to such properties has been completed and, as of December 31, 2018 , management believes that there are no obligations related to environmental remediation other than maintaining the affected sites in conformity with the relevant authority’s mandates and filing the required documents. All such maintenance costs are expensed as incurred. We expect that resolution of the environmental matters relating to the above will not have a material impact on our business, assets, consolidated and combined financial condition, results of operations or liquidity. However, we cannot be certain that we have identified all environmental liabilities at our properties, that all necessary remediation actions have been or will be undertaken at our properties or that we will be indemnified, in full or at all, in the event that such environmental liabilities arise. Insurance Coverage We carry insurance coverage on our properties of types and in amounts with deductibles that we believe are in line with coverage customarily obtained by owners of similar properties. Multiemployer Pension and Defined Contribution Plans We contribute to a number of multiemployer defined benefit pension plans under the terms of collective bargaining agreements that cover our union-represented employees. The risks of participating in these multiemployer plans are different from single-employer plans in the following respects: • Assets contributed to the multiemployer plan by one employer may be used to provide benefits to employees of other participating employers. • If a participating employer stops contributing to the plan, the unfunded obligations of the plan may be borne by the remaining participating employers. • If we choose to stop participating in some of our multiemployer plans, we may be required to pay those plans an amount based on the underfunded status of the plan, referred to as a withdrawal liability. We participate in various unions. The union in which we have significant employees and costs is 32BJ. 32BJ We participate in the Building Service 32BJ, ("Union"), Pension Plan and Health Plan. The Pension Plan is a multi-employer, non-contributory defined benefit pension plan that was established under the terms of collective bargaining agreements between the Service Employees International Union, Local 32BJ, the Realty Advisory Board on Labor Relations, Inc. and certain other employers. This Pension Plan is administered by a joint board of trustees consisting of union trustees and employer trustees and operates under employer identification number 13-1879376. The Pension Plan year runs from July 1 to June 30. Employers contribute to the Pension Plan at a fixed rate on behalf of each covered employee. Separate actuarial information regarding such pension plans is not made available to the contributing employers by the union administrators or trustees, since the plans do not maintain separate records for each reporting unit. However, on September 28, 2016, September 28, 2017 and September 28, 2018, the actuary certified that for the plan years beginning July 1, 2016, July 1, 2017 and July 1, 2018, respectively, the Pension Plan was in critical status under the Pension Protection Act of 2006. The Pension Plan trustees adopted a rehabilitation plan consistent with this requirement. For each of the years ended June 30, 2018, 2017 and 2016, the Pension Plan received contributions from employers totaling $272.3 million , $257.8 million and $249.5 million , respectively. The Health Plan was established under the terms of collective bargaining agreements between the Union, the Realty Advisory Board on Labor Relations, Inc. and certain other employers. The Health Plan provides health and other benefits to eligible participants employed in the building service industry who are covered under collective bargaining agreements, or other written agreements, with the Union. The Health Plan is administered by a Board of Trustees with equal representation by the employers and the Union and operates under employer identification number 13-2928869. The Health Plan receives contributions in accordance with collective bargaining agreements or participation agreements. Generally, these agreements provide that the employers contribute to the Health Plan at a fixed rate on behalf of each covered employee. For the years ended June 30, 2018, 2017 and 2016, the Health Plan received contributions from employers totaling $1.4 billion , $1.3 billion and $1.2 billion , respectively. Term of Collective Bargaining Agreement The most recent collective bargaining agreement for Local 32BJ commenced from January 1, 2016 and runs through December 31, 2019. Contributions Contributions we made to the multi-employer plans for the years ended December 31, 2018, 2017 and 2016 are included in the table below (amounts in thousands): For the Year Ended December 31, Benefit Plan 2018 2017 2016 Pension Plans (pension and annuity)* $ 3,327 $ 3,035 $ 3,155 Health Plans** 9,373 8,551 8,280 Other*** 814 856 542 Total plan contributions $ 13,514 $ 12,442 $ 11,977 * Pension plans include $1.0 million, $0.9 million and $0.8 million for the years ended 2018, 2017 and 2016, respectively, to multiemployer plans not discussed above. ** Health plans include $1.6 million, $1.6 million and $1.6 million for the years ended 2018, 2017 and 2016, respectively, to multiemployer plans not discussed above. *** Other consists of union costs which were not itemized between pension and health plans. Other includes $0.2 million, $0.2 million and $0.2 million for the years ended 2018, 2017 and 2016, respectively, in connection with other multiemployer plans not discussed above. Benefit plan contributions are included in operating expenses in our consolidated statements of income.

Equity

Equity	12 Months Ended
	Dec. 31, 2018
Stockholders' Equity Note Disclosure, Disclosure of Compensation Related Costs, Share-based Payments and Earnings Per Share [Abstract]
Equity	Equity During 2016, Q REIT Holding LLC, a Qatar Financial Centre limited liability company and a wholly owned subsidiary of the Qatar Investment Authority, a governmental authority of the State of Qatar ("QREIT", and together with any eligible transferee, "QIA"), purchased 29,610,854 newly issued Class A common shares at $21.00 per share, equivalent to a 9.9% economic interest in us on a fully diluted basis (representing a 19.4% ownership of Class A common shares). However, QIA can only vote shares equivalent to 9.9% of all voting securities, with the balance of their shares to be voted by us in accord with the votes of all other voting securities. We received approximately $621.8 million in gross proceeds from this 2016 sale to QREIT. QIA has a top-up right to acquire a pro rata number of additional shares from us in the future should we issue new shares to third parties. During the second quarter of 2018, pursuant to an August 2016 stockholders agreement between us and QIA , we sold 284,015 shares of Class A common stock (the “Top Up Shares”) to QIA pursuant to its top-up right to acquire its 9.9% pro rata share of new equity securities issued during the first quarter of 2018 (in this case, equity compensation). The aggregate purchase price which QIA paid to us for the Top Up Shares was $4.7 million , or $16.72 per share of Class A common stock, in accordance with a formula in the stockholders agreement equal to the average closing price per share during the five (5) consecutive trading days immediately preceding the issuance of the applicable new equity securities. Shares and Units An operating partnership unit ("OP Unit") and a share of our common stock have essentially the same economic characteristics as they receive the same per unit profit distributions of our operating partnership. On the one-year anniversary of issuance, an OP Unit may be tendered for redemption for cash, however, we have sole and absolute discretion and the authorized common stock to exchange for shares of common stock on a one-for-one basis instead of cash. Long-term incentive plan ("LTIP") units are a special class of partnership interests in our operating partnership. Each LTIP unit awarded will be deemed equivalent to an award of one share of stock under the Empire State Realty Trust Inc. Empire State Realty OP, L.P. 2013 Equity Incentive Plan ("2013 Plan"), reducing the availability for other equity awards on a one-for-one basis. The vesting period for LTIP units, if any, will be determined at the time of issuance. Under the terms of the LTIP units, our operating partnership will revalue for tax purposes its assets upon the occurrence of certain specified events, and any increase in valuation from the time of grant until such event will be allocated first to the holders of LTIP units to equalize the capital accounts of such holders with the capital accounts of OP unitholders. Subject to any agreed upon exceptions, once vested and having achieved parity with OP unitholders, LTIP units are convertible into OP Units in our operating partnership on a one-for-one basis. LTIP units subject to time based vesting, whether vested or not, receive the same per unit distributions as OP Units, which equal per share dividends (both regular and special) on our common stock. Market based LTIP units receive 10% of such distributions currently, unless and until such LTIP units are earned based on performance, at which time they will receive the accrued and unpaid 90% and will commence receiving 100% of such distributions thereafter. The following is net income attributable to common stockholders and the issuance of our class A shares in exchange for the conversion of OP Units into common stock (amounts in thousands): Year ended December 31, 2018 2017 2016 Net income attributable to common stockholders $ 65,603 $ 62,647 $ 51,456 Increase in additional paid-in capital for the conversion of OP Units into common stock 70,452 23,529 24,044 Change from net income attributable to common stockholders and transfers from noncontrolling interests $ 136,055 $ 86,176 $ 75,500 As of December 31, 2018 , there were approximately 303.3 million common stock and OP Units outstanding, of which approximately 174.9 million , or 57.7% , were owned by us and approximately 128.4 million , or 42.3% , were owned by other partners, including certain directors, officers and other members of executive management. Private Perpetual Preferred Units As of December 31, 2018 , there were 1,560,360 Private Perpetual Preferred Units ("Preferred Units") which have a liquidation preference of $16.62 per unit and which are entitled to receive cumulative preferential annual cash distributions of $0.60 per unit payable in arrears on a quarterly basis. The Preferred Units are not redeemable at the option of the holders and are redeemable at our option only in the case of specific defined events. Dividends and Distributions The following table summarizes the dividends paid on our Class A common stock and Class B common stock for the years ended December 31, 2018, 2017 and 2016: Record Date Payment Date Amount per Share December 17, 2018 December 31, 2018 $0.105 September 14, 2018 September 28, 2018 $0.105 June 15, 2018 June 29, 2018 $0.105 March 15, 2018 March 30, 2018 $0.105 December 15, 2017 December 29, 2017 $0.105 September 15, 2017 September 29, 2017 $0.105 June 15, 2017 June 30, 2017 $0.105 March 15, 2017 March 31, 2017 $0.105 December 15, 2016 December 29, 2016 $0.105 September 19, 2016 September 30, 2016 $0.105 June 15, 2016 June 30, 2016 $0.105 March 16, 2016 March 31, 2016 $0.085 Total dividends paid to common securityholders during 2018, 2017 and 2016 were $70.9 million , $66.8 million and $55.8 million , respectively. Total distributions paid to OP unitholders, excluding inter-company distributions, during 2018, 2017 and 2016 totaled $54.7 million , $59.2 million and $58.2 million , respectively. Total distributions paid to Preferred unitholders during 2018, 2017 and 2016 were $0.9 million , $0.9 million , and $0.9 million , respectively. Earnings and profits, which determine the tax treatment of distributions to securityholders, will differ from income reported for financial reporting purposes due to the differences for federal income tax purposes, including, but not limited to, treatment of loss on extinguishment of debt, revenue recognition, compensation expense, and basis of depreciable assets and estimated useful lives used to compute depreciation. The 2018 dividends of $0.42 per share are classified for income tax purposes 83.8% as taxable ordinary dividends eligible for the Section 199A deduction and 16.2% as a return of capital. The 2017 and 2016 dividends of $0.42 and $0.40 per share, respectively, are classified for income tax purposes as 100.0% taxable ordinary dividends. Incentive and Share-Based Compensation The 2013 Plan provides for grants to our directors, employees and consultants consisting of stock options, restricted stock, dividend equivalents, stock payments, performance shares, LTIP units, stock appreciation rights and other incentive awards. An aggregate of approximately 12.2 million shares of our common stock are authorized for issuance under awards granted pursuant to the 2013 Plan, and as of December 31, 2018 , approximately 4.3 million shares of common stock remain available for future issuance. In May 2018, we made grants of LTIP units to our non-employee directors under the 2013 Plan. At such time, we granted a total of 65,000 LTIP units that are subject to time-based vesting with fair market values of $1.0 million . The awards vest ratably over three years from the date of the grant, subject generally to the director's continued service on our Board of Directors. In March 2018, we made grants of LTIP units to executive officers under the 2013 Plan. At such time, we granted to executive officers a total of 386,876 LTIP units that are subject to time-based vesting and 1,737,917 LTIP units that are subject to market-based vesting, with fair market values of $6.1 million for the time-based vesting awards and $9.6 million for the market-based vesting awards. In March 2018, we made grants of LTIP units and restricted stock to certain other employees under the 2013 Plan. At such time, we granted to certain other employees a total of 67,449 LTIP units and 39,608 shares of restricted stock that are subject to time-based vesting and 223,950 LTIP units that are subject to market-based vesting, with fair market values of $1.7 million for the time-based vesting awards and $1.1 million for the market-based vesting awards. The awards subject to time-based vesting vest ratably over four years from January 1, 2018, subject generally to the grantee's continued employment. The first installment vests on January 1, 2019 and the remainder will vest thereafter in three equal annual installments. The vesting of the LTIP units subject to performance-based vesting is based on the achievement of absolute and relative total stockholder return hurdles over a three -year performance period, commencing on January 1, 2018. Following the completion of the three -year performance period, our compensation committee will determine the number of LTIP units to which the grantee is entitled based on our performance relative to the performance hurdles set forth in the LTIP unit award agreements the grantee entered into in connection with the award grant. These units then vest in two installments, with the first installment vesting on January 1, 2021 and the second installment vesting on January 1, 2022, subject generally to the grantee's continued employment on those dates. In 2017, our board of directors determined to reinforce the alignment of our executive officers’ interests with that of stockholders by designing a new bonus election program, under which named executive officers could elect to receive their annual incentive bonus in any combination of (i) cash or vested LTIP's at the face amount of such bonus or (ii) time-vesting LTIP's which would vest over three years, subject to continued employment, at 125% of such face amount. In February 2018, we made grants of LTIP units to executive officers under the 2013 Plan in connection with the 2017 bonus election program. We granted to executive officers a total of 238,609 LTIP units that are subject to time based vesting with a fair market value $4.0 million . Of these LTIP units, 25,158 LTIP units vested immediately on the grant date and 213,451 LTIP units vest ratably over three years from January 1, 2018, subject generally to the grantee's continued employment. The first installment vests on January 1, 2019 and the remainder will vest thereafter in two equal annual installments. In May 2017, we made grants of LTIP units to our non-employee directors under the 2013 Plan. At such time, we granted a total of 50,408 LTIP units that are subject to time-based vesting with fair market values of $1.0 million . The awards vest ratably over three years from the date of the grant, subject generally to the director's continued service on our Board of Directors. In March 2017, we made grants of LTIP units to executive officers under the 2013 Plan. At such time, we granted to executive officers a total of 313,275 LTIP units that are subject to time-based vesting and 865,742 LTIP units that are subject to market-based vesting, with fair market values of $6.1 million for the time-based vesting awards and $9.6 million for the market-based vesting awards. In March 2017, we made grants of LTIP units and restricted stock to certain other employees under the 2013 Plan. At such time, we granted to certain other employees a total of 47,993 LTIP units and 34,407 shares of restricted stock that are subject to time-based vesting and 95,156 LTIP units that are subject to market-based vesting, with fair market values of $1.6 million for the time-based vesting awards and $1.0 million for the market-based vesting awards. The awards subject to time-based vesting vest ratably over four years from January 1, 2017, subject generally to the grantee's continued employment. The first installment vests on January 1, 2018 and the remainder will vest thereafter in three equal annual installments. The vesting of the LTIP units subject to performance-based vesting is based on the achievement of absolute and relative total stockholder return hurdles over a three -year performance period, commencing on January 1, 2017. Following the completion of the three -year performance period, our compensation committee will determine the number of LTIP units to which the grantee is entitled based on our performance relative to the performance hurdles set forth in the LTIP unit award agreements the grantee entered into in connection with the award grant. These units then vest in two installments, with the first installment vesting on January 1, 2020 and the second installment vesting on January 1, 2021, subject generally to the grantee's continued employment on those dates. Share-based compensation is measured at the fair value of the award on the date of grant and recognized as an expense on a straight-line basis over the vesting period. For the market-based LTIP units and restricted stock awards, the fair value of the awards was estimated using a Monte Carlo Simulation model. Our stock price, along with the prices of the comparative indexes, is assumed to follow the Geometric Brownian Motion Process. Geometric Brownian motion is a common assumption when modeling in financial markets, as it allows the modeled quantity (in this case, the stock price) to vary randomly from its current value and take any value greater than zero . The volatilities of the returns on our stock price and the comparative indexes were estimated based on implied volatilities and historical volatilities using a six -year look-back period. The expected growth rate of the stock prices over the performance period is determined with consideration of the risk free rate as of the grant date. For LTIP unit awards that are time-based, the fair value of the awards was estimated based on the fair value of our stock at the grant date discounted for the restriction period during which the LTIP units cannot be redeemed or transferred and the uncertainty regarding if, and when, the book capital account of the LTIP units will equal that of the common units. For restricted stock awards that are time-based, we estimate the stock compensation expense based on the fair value of the stock at the grant date. LTIP units and restricted stock issued during the year ended December 31, 2018, 2017 and 2016 were valued at $23.6 million , $19.4 million and $18.4 million , respectively. The weighted-average per unit or share fair value was $8.54 , $13.77 and $9.60 for grants issued in 2018, 2017 and 2016, respectively. The per unit or share granted in 2018 was estimated on the respective dates of grant using the following assumptions: an expected life of 2.8 years, a dividend rate of 2.30% , a risk-free interest rate of 2.50% and an expected price volatility of 20.0% . The per unit or share granted in 2017 was estimated on the respective dates of grant using the following assumptions: an expected life of 2.8 years, a dividend rate of 2.05% , a risk-free interest rate of 1.55% and an expected price volatility of 20.0% . The per unit or share granted in 2016 was estimated on the respective dates of grant using the following assumptions: an expected life of 2.8 years, a dividend rate of 2.10% , a risk-free interest rate of 0.84% and an expected price volatility of 24.0% . No other stock options, dividend equivalents, or stock appreciation rights were issued or outstanding in 2018, 2017 and 2016. The following is a summary of restricted stock and LTIP unit activity for the year ended December 31, 2018 : Restricted Stock LTIP Units Weighted Average Grant Fair Value Unvested balance at December 31, 2017 90,791 3,588,609 $ 11.20 Vested (30,693 ) (495,303 ) 14.59 Granted 39,608 2,719,801 8.54 Forfeited or unearned (8,548 ) (110,286 ) 8.50 Unvested balance at December 31, 2018 91,158 5,702,821 $ 9.68 The total fair value of LTIP units and restricted stock that vested during 2018, 2017 and 2016 was $7.7 million , $7.6 million and $5.1 million , respectively. The LTIP unit and restricted stock award agreements will immediately vest when a grantee attains the (i) age of 60 and (ii) the date on which grantee has first completed ten years of continuous service with us or our affiliates. For award agreements that qualify, we recognize noncash compensation expense on the grant date for the time-based awards and ratably over the vesting period for the market-based awards, and accordingly, we recognized $1.8 million , $1.0 million and $0.7 million for the years ended December 31, 2018, 2017 and 2016, respectively. Unrecognized compensation expense was $1.0 million at December 31, 2018, which will be recognized over a weighted average period of 2.1 years . For the remainder of the LTIP unit and restricted stock awards, we recognize noncash compensation expense ratably over the vesting period, and accordingly, we recognized $17.0 million , $13.1 million and $9.0 million in noncash compensation expense for the years ended December 31, 2018, 2017 and 2016, respectively. Unrecognized compensation expense was $27.4 million at December 31, 2018, which will be recognized over a weighted average period of 2.2 years . Earnings Per Share Earnings per share for the years ended December 31, 2018 , 2017 and 2016 is computed as follows (amounts in thousands, except per share amounts): For the Year Ended December 31, 2018 2017 2016 Numerator - Basic: Net income $ 117,253 $ 118,253 $ 107,250 Private perpetual preferred unit distributions (936 ) (936 ) (936 ) Net income attributable to non-controlling interests (50,714 ) (54,670 ) (54,858 ) Earnings allocated to unvested shares (38 ) (36 ) (36 ) Net income attributable to common stockholders - basic $ 65,565 $ 62,611 $ 51,420 Numerator - Diluted: Net income $ 117,253 $ 118,253 $ 107,250 Private perpetual preferred unit distributions (936 ) (936 ) (936 ) Earnings allocated to unvested shares (38 ) (36 ) (36 ) Net income attributable to common stockholders - diluted $ 116,279 $ 117,281 $ 106,278 Denominator: Weighted average shares outstanding - basic 167,571 158,380 133,881 Operating partnership units 129,687 138,075 142,967 Effect of dilutive securities: Stock-based compensation plans 1 775 454 Exchangeable senior notes — 819 266 Weighted average shares outstanding - diluted 297,259 298,049 277,568 Earnings per share - basic $ 0.39 $ 0.40 $ 0.38 Earnings per share - diluted $ 0.39 $ 0.39 $ 0.38 There were 485,865 , 834,267 , and 800,746 antidilutive shares for the years ended December 31, 2018, 2017 and 2016, respectively.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions QIA In connection with any new issuance by us of common equity securities, for so long as QIA maintains at least a 5.0% fully diluted economic interest in us and remains in material compliance with the terms of the stockholders agreement, QIA will have the right (but not the obligation) to purchase its pro rata share of such new equity securities in the form of newly issued shares of Class A common stock. These “top up” rights are generally exercisable on a quarterly basis, or sooner if we or the operating partnership issues new equity securities in an issuance in excess of $1.0 million . Through August 2021, to the extent QIA remains in material compliance with the terms of the Stockholders Agreement, QIA will have the right of first offer to co-invest with us as a joint venture partner in real estate investment opportunities initiated by us where we have elected, at our discretion, to seek a joint venture partner. The right of first offer period will be extended for a 30 -month term if at least one joint venture transaction is consummated among us and QIA during the initial five year term, and will be extended for a further 30 -month term if at least one joint venture transaction is consummated during such initial 30 -month extension term. Subject to certain minimum thresholds and conditions, we will indemnify QIA for certain applicable U.S. federal and state taxes payable by QIA in connection with dividends paid by us on the QIA shares that are attributable to capital gains from the sale or exchange of any U.S. real property interests. Our obligation to indemnify QIA will terminate one year following the date on which the sum of the QIA shares then owned by QIA falls below 10% of our outstanding common shares. Tax Protection Agreement In 2013, we entered into a tax protection agreement with Anthony E. Malkin and Peter L. Malkin that is intended to protect to a limited extent the Malkin Group and an additional third party investor in Metro Center (who was one of the original landowners and was involved in the development of the property) against certain tax consequences arising from a transaction involving one of four properties, which we refer to in this section as the protected assets. First, this agreement provides that our operating partnership will not sell, exchange, transfer or otherwise dispose of such protected assets, or any interest in a protected asset, until (i) October 7, 2025, with respect to one protected asset, First Stamford Place, and (ii) the later of (x) October 7, 2021 and (y) the death of both Peter L. Malkin and Isabel W. Malkin, who are 85 and 82 years old, respectively, for the three other protected assets, Metro Center, 10 Bank Street and 1542 Third Avenue, unless: (1) Anthony E. Malkin consents to the sale, exchange, transfer or other disposition; or (2) our operating partnership delivers to each protected party thereunder a cash payment intended to approximate the tax liability arising from the recognition of the pre-contribution built-in gain resulting from the sale, exchange, transfer or other disposition of such protected asset (with the pre-contribution “built-in gain” being not more than the taxable gain that would have been recognized by such protected party if the protected asset been sold for fair market value in a taxable transaction at the time of the consolidation) plus an additional amount so that, after the payment of all taxes on amounts received pursuant to the agreement (including any tax liability incurred as a result of receiving such payment), the protected party retains an amount equal to such protected party’s total tax liability incurred as a result of the recognition of the pre-contribution built-in gain pursuant to such sale, exchange, transfer or other disposition; or (3) the disposition does not result in a recognition of any built-in gain by the protected party. Second, with respect to the Malkin Group, including Anthony E. Malkin and Peter L. Malkin, and one additional third party investor in Metro Center (who was one of the original landowners and was involved in the development of the property), to protect against gain recognition resulting from a reduction in such continuing investor’s share of the operating partnership liabilities, the agreement provides that during the period from October 7, 2013 until such continuing investor owns less than the aggregate number of operating partnership units and shares of common stock equal to 50% of the aggregate number of such units and shares such investor received in the formation transactions, which we refer to in this section as the tax protection period, our operating partnership will (i) refrain from prepaying any amounts outstanding under any indebtedness secured by the protected assets and (ii) use its commercially reasonable efforts to refinance such indebtedness at or prior to maturity at its current principal amount, or, if our operating partnership is unable to refinance such indebtedness at its current principal amount, at the highest principal amount possible. The agreement also provides that, during the tax protection period, our operating partnership will make available to such continuing investors the opportunity (i) to enter into a “bottom dollar” guarantee of their allocable share of $160.0 million of aggregate indebtedness of our operating partnership meeting certain requirements or (ii) in the event our operating partnership has recourse debt outstanding and such a continuing investor agrees, in lieu of guaranteeing debt pursuant to clause (i) above, to enter into a deficit restoration obligation, in each case, in a manner intended to provide an allocation of operating partnership liabilities to the continuing investor. In the event that a continuing investor guarantees debt of our operating partnership, such continuing investor will be responsible, under certain circumstances, for the repayment of the guaranteed amount to the lender in the event that the lender would otherwise recognize a loss on the loan, such as, for example, if property securing the loan was foreclosed and the value was not sufficient to repay a certain amount of the debt. A deficit restoration obligation is a continuing investor’s obligation, under certain circumstances, to contribute a designated amount of capital to our operating partnership upon our operating partnership’s liquidation in the event that the assets of our operating partnership are insufficient to repay our operating partnership liabilities. Because we expect that our operating partnership will at all times have sufficient liabilities to allow it to meet its obligations to allocate liabilities to its partners that are protected parties under the tax protection agreement, our operating partnership’s indemnification obligation with respect to “certain tax liabilities” would generally arise only in the event that the operating partnership disposes in a taxable transaction of a protected asset within the period specified above in a taxable transaction. In the event of such a disposition, the amount of our operating partnership’s indemnification obligation would depend on several factors, including the amount of “built-in gain,” if any, recognized and allocated to the indemnified partners with respect to such disposition and the effective tax rate to be applied to such gain at the time of such disposition. The operating partnership agreement requires that allocations with respect to such acquired property be made in a manner consistent with Section 704(c) of the Code. Treasury Regulations issued under Section 704(c) of the Code provide partnerships with a choice of several methods of allocating book-tax differences. Under the tax protection agreement, our operating partnership has agreed to use the “traditional method” for accounting for book-tax differences for the properties acquired by our operating partnership in the consolidation. Under the traditional method, which is the least favorable method from our perspective, the carryover basis of the acquired properties in the hands of our operating partnership (i) may cause us to be allocated lower amounts of depreciation and other deductions for tax purposes than would be allocated to us if all of the acquired properties were to have a tax basis equal to their fair market value at the time of acquisition and (ii) in the event of a sale of such properties, could cause us to be allocated gain in excess of its corresponding economic or book gain (or taxable loss that is less than its economic or book loss), with a corresponding benefit to the partners transferring such properties to our operating partnership for interests in our operating partnership. Registration Rights We entered into a registration rights agreement with certain persons receiving shares of our common stock or operating partnership units in the formation transactions, including certain members of our senior management team and our other continuing investors. In connection therewith, we have filed, and are obligated to maintain the effectiveness of, an automatically effective shelf registration statement, along with a prospectus supplement, with respect to, among other things, shares of our Class A common stock that may be issued upon redemption of operating partnership units or issued upon conversion of shares of Class B common stock to continuing investors in the public existing entities. Pursuant to the registration rights agreement, under certain circumstances, we will also be required to undertake an underwritten offering upon the written request of the Malkin Group, which we refer to as the holder, provided (i) the registrable shares to be registered in such offering will have a market value of at least $150.0 million , (ii) we will not be obligated to effect more than two underwritten offerings during any 12-month period; and (iii) the holder will not have the ability to effect more than four underwritten offerings. In addition, if we file a registration statement with respect to an underwritten offering for our own account or on behalf of the holder, the holder will have the right, subject to certain limitations, to register such number of registrable shares held by him, her or it as each such holder requests. With respect to underwritten offerings on behalf of the holder, we will have the right to register such number of primary shares as we request; provided, however, that if cut backs are required by the managing underwriters of such an offering, our primary shares shall be cutback first (but in no event will our shares be cut back to less than $25.0 million ). We have also agreed to indemnify the persons receiving rights against specified liabilities, including certain potential liabilities arising under the Securities Act, or to contribute to the payments such persons may be required to make in respect thereof. We have agreed to pay all of the expenses relating to the registration and any underwritten offerings of such securities, including, without limitation, all registration, listing, filing and stock exchange or FINRA fees, all fees and expenses of complying with securities or “blue sky” laws, all printing expenses and all fees and disbursements of counsel and independent public accountants retained by us, but excluding underwriting discounts and commissions, any out-of-pocket expenses (except we will pay any holder’s out-of-pocket fees (including disbursements of such holder’s counsel, accountants and other advisors) up to $25,000 in the aggregate for each underwritten offering and each filing of a resale shelf registration statement or demand registration statement), and any transfer taxes. Employment Agreement and Change in Control Severance Agreements We entered into an employment agreement with Anthony E. Malkin, which provides for salary, bonuses and other benefits, including among other things, severance benefits upon a termination of employment under certain circumstances and the issuance of equity awards. In addition, we entered into change in control severance agreements with Thomas P. Durels, David A. Karp, Thomas N. Keltner, Jr. and John B. Kessler. Indemnification of Our Directors and Officers We entered into indemnification agreements with each of our directors, executive officers, chairman emeritus and certain other parties, providing for the indemnification by us for certain liabilities and expenses incurred as a result of actions brought, or threatened to be brought, against (i) our directors, executive officers and chairman emeritus and (ii) our executive officers, chairman emeritus and certain other parties who are former members, managers, securityholders, directors, limited partners, general partners, officers or controlling persons of our predecessor in such capacities. Excluded Properties and Businesses The Malkin Group, including Anthony E. Malkin, our Chairman and Chief Executive Officer, owns non-controlling interests in, and Anthony E. Malkin and Peter L. Malkin control the general partners or managers of, the entities that own interests in eight multi-family properties, five net leased retail properties, (including one single tenant retail property in Greenwich, Connecticut), and a parcel that is being developed for residential use. The Malkin Group also owns non-controlling interests in one Manhattan office property, two Manhattan retail properties and several retail properties outside of Manhattan, none of which were contributed to us in the formation transactions. We refer to the non-controlling interests described above collectively as the excluded properties. In addition, the Malkin Group owns interests in two mezzanine and senior equity funds, an industrial fund, and five residential properties, and which we refer to collectively as the excluded businesses. Other than the Greenwich retail property, we do not believe that the excluded properties or the excluded businesses are consistent with our portfolio geographic or property type composition, management or strategic direction. Pursuant to management and/or service agreements with the owners of interests in those excluded properties and services agreements with five residential property managers and the managers of certain other excluded businesses which historically were managed by affiliates of our predecessor, we are designated as the asset manager (supervisor) and/or property manager of the excluded properties and will provide services to the owners of certain of the excluded properties and the five residential property managers and provide services and access to office space to the existing managers of the other excluded businesses. As the manager or service provider, we are paid a management or other fee with respect to those excluded properties and excluded businesses where our predecessor had previously received a management fee on the same terms as the fee paid to our predecessor, and reimbursed for our costs in providing the management and other services to those excluded properties and businesses where our predecessor had not previously received a management fee. Our management of the excluded properties and provision of services to the five residential property managers and the existing managers of the other excluded businesses represent a minimal portion of our overall business. There is no established time period in which we will manage such properties or provide services to the owners of certain of the excluded properties and the five residential property managers and provide services and access to office space to the existing managers of the other excluded businesses; and Peter L. Malkin and Anthony E. Malkin expect to sell certain properties or unwind these businesses over time. We are not precluded from acquiring all or certain interests in the excluded properties or businesses. If we were to attempt any such acquisition, we anticipate that Anthony E. Malkin, our Chairman and Chief Executive Officer, will not participate in the negotiation process on our behalf with respect to our potential acquisition of any of these excluded properties or businesses, and the approval of a majority of our independent directors will be required to approve any such acquisition. Services are and were provided by us to excluded properties and businesses. These transactions are reflected in our consolidated statements of income as third-party management and other fees. We earned asset management (supervisory) and service fees from excluded properties and businesses of $1.1 million , $1.1 million and $1.4 million during the years ended December 31, 2018 , 2017 and 2016, respectively. We earned property management fees from excluded properties of $0.3 million , $0.3 million and $0.4 million during the years ended December 31, 2018 , 2017 and 2016, respectively. Other We were reimbursed at allocable cost for 647 square feet of shared office space, equipment, and administrative support shared with us in our corporate offices, as was done prior to our formation, and we received rent generally at market rental rate for 3,074 square feet of leased space, from entities affiliated with Anthony E. Malkin at one of our properties. Total revenue aggregated $0.2 million for the year ended December 31, 2016. During August 2016, such entities moved from the previously shared office and leased spaces to relocate to a new 5,351 square foot leased space at one of our properties, paying rent generally at a market rental rate. Under such new lease, the tenant has the right to cancel such lease without special payment on 90 days’ notice. We now have a shared use agreement with such tenant, to occupy a portion of the leased premises as the office location for Peter L. Malkin, our chairman emeritus and employee, utilizing approximately 15% of the space, for which we pay an allocable pro rata share of the cost to such tenant. We also have agreements with these entities and excluded properties and businesses to provide them with general computer-related support. Total revenue aggregated $ 0.3 million , $0.4 million and $0.1 million for the years ended December 31, 2018, 2017 and 2016, respectively. During 2016 and in connection with our office move, Peter L. Malkin purchased miscellaneous furniture and artwork from us at their appraised value of $23,300 . Remaining office furniture was disposed. One of our directors, James D. Robinson IV, is a general partner in an investment fund, which owns more than a 10% economic and voting interest in one of our tenants, OnDeck Capital, with an annualized rent of $4.5 million and $5.8 million as of December 31, 2018 and 2017, respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes TRS Holdings and Observatory TRS are taxable entities and their consolidated provision for income taxes consisted of the following for the years ended December 31, 2018 , 2017 and 2016 (amounts in thousands): For the Year Ended December 31, 2018 2017 2016 Current: Federal $ (2,389 ) $ (3,923 ) $ (3,632 ) State and local (2,253 ) (2,304 ) (2,055 ) Total current (4,642 ) (6,227 ) (5,687 ) Deferred: Federal — (446 ) (291 ) State and local — — (168 ) Total deferred — (446 ) (459 ) Income tax expense $ (4,642 ) $ (6,673 ) $ (6,146 ) In December 2017, the Tax Cuts and Jobs Act (the “TCJA”) was enacted. The TCJA includes a number of changes to existing U.S. tax laws, most notably a reduction of the U.S. corporate income tax rate from 35 percent to 21 percent, effective January 1, 2018. We measure deferred tax assets using enacted tax rates that will apply in the years in which the temporary differences are expected to be recovered or paid. Accordingly, our deferred tax assets were remeasured to reflect the reduction in the U.S. corporate income tax rate, resulting in a $0.4 million increase in income tax expense for the year ended December 31, 2017 and a corresponding decrease of the same amount in our deferred assets as of December 31, 2017. The effective income tax rate is 34.0% , 48.5% and 44.8% for the years ended December 31, 2018 , 2017 and 2016, respectively. The actual tax provision differed from that computed at the federal statutory corporate rate as follows (amounts in thousands): For the Year Ended December 31, 2018 2017 2016 Federal tax expense at statutory rate $ (2,844 ) $ (4,684 ) $ (4,629 ) State income taxes, net of federal benefit (1,798 ) (1,543 ) (1,517 ) Corporate income tax rate adjustment — (446 ) — Income tax expense $ (4,642 ) $ (6,673 ) $ (6,146 ) The income tax effects of temporary differences that give rise to deferred tax assets are presented below as of December 31, 2018 , 2017 and 2016 (amounts in thousands): 2018 2017 2016 Deferred tax assets: Deferred revenue on unredeemed observatory admission ticket sales $ 1,396 $ 1,395 $ 198 Deferred tax assets at December 31, 2018, 2017 and 2016, respectively, are attributable to the inclusion of deferred revenue on Observatory admission ticket sales not redeemed at year-end in determining income for tax reporting purposes and are included in prepaid expenses and other assets on the consolidated balance sheets. No valuation allowance has been recorded against the deferred tax asset because the Company believes that the deferred tax asset will, more likely than not, be realized. This determination is based on the Observatory TRS’s anticipated future taxable income and the reversal of the deferred tax asset. At December 31, 2018 , 2017 and 2016, the TRS entities have no amount of unrecognized tax benefits. For tax years 2018, 2017, 2016 and 2015, the United States federal and state tax returns are open for examination.

Segment Reporting

Segment Reporting	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Segment Reporting	Segment Reporting We have identified two reportable segments: (1) Real Estate and (2) Observatory. Our real estate segment includes all activities related to the ownership, management, operation, acquisition, repositioning and disposition of our real estate assets. Our observatory segment operates the 86th and 102nd floor observatories at the Empire State Building. These two lines of businesses are managed separately because each business requires different support infrastructures, provides different services and has dissimilar economic characteristics such as investments needed, stream of revenues and different marketing strategies. We account for intersegment sales and rents as if the sales or rents were to third parties, that is, at current market prices. The following tables provide components of segment profit for each segment for the years ended December 31, 2018 , 2017 and 2016, as reviewed by management (amounts in thousands): 2018 Real Estate Observatory Intersegment Elimination Total Revenues: Rental revenue $ 493,231 $ — $ — $ 493,231 Intercompany rental revenue 79,954 — (79,954 ) — Tenant expense reimbursement 72,372 — — 72,372 Observatory revenue — 131,227 — 131,227 Lease termination fees 20,847 — — 20,847 Third-party management and other fees 1,440 — — 1,440 Other revenue and fees 12,394 — — 12,394 Total revenues 680,238 131,227 (79,954 ) 731,511 Operating expenses: Property operating expenses 167,379 — — 167,379 Intercompany rent expense — 79,954 (79,954 ) — Ground rent expense 9,326 — — 9,326 General and administrative expenses 52,674 — — 52,674 Observatory expenses — 32,767 — 32,767 Real estate taxes 110,000 — — 110,000 Depreciation and amortization 168,430 78 — 168,508 Total operating expenses 507,809 112,799 (79,954 ) 540,654 Total operating income 172,429 18,428 — 190,857 Other income (expense): Interest income 10,661 — — 10,661 Interest expense (79,623 ) — — (79,623 ) Income before income taxes 103,467 18,428 — 121,895 Income tax expense (1,114 ) (3,528 ) — (4,642 ) Net income $ 102,353 $ 14,900 $ — $ 117,253 Segment assets $ 3,930,330 $ 265,450 $ — $ 4,195,780 Expenditures for segment assets $ 201,685 $ 54,811 $ — $ 256,496 2017 Real Estate Observatory Intersegment Elimination Total Revenues: Rental revenue $ 483,944 $ — $ — $ 483,944 Intercompany rental revenue 77,646 — (77,646 ) — Tenant expense reimbursement 73,679 — — 73,679 Observatory revenue — 127,118 — 127,118 Lease termination fees 13,551 — — 13,551 Third-party management and other fees 1,400 — — 1,400 Other revenue and fees 9,834 — — 9,834 Total revenues 660,054 127,118 (77,646 ) 709,526 Operating expenses: Property operating expenses 163,531 — — 163,531 Intercompany rent expense — 77,646 (77,646 ) — Ground rent expense 9,326 — — 9,326 General and administrative expenses 50,315 — — 50,315 Observatory expenses — 30,275 — 30,275 Real estate taxes 102,466 — — 102,466 Depreciation and amortization 160,630 80 — 160,710 Total operating expenses 486,268 108,001 (77,646 ) 516,623 Total operating income (loss) 173,786 19,117 — 192,903 Other income (expense): Interest income 2,942 — — 2,942 Interest expense (68,473 ) — — (68,473 ) Loss on early extinguishment of debt (2,157 ) — — (2,157 ) Loss from derivative financial instrument (289 ) — — (289 ) Income before income taxes 105,809 19,117 — 124,926 Income tax expense (1,306 ) (5,367 ) — (6,673 ) Net income $ 104,503 $ 13,750 $ — $ 118,253 Segment assets $ 3,670,907 $ 260,440 $ — $ 3,931,347 Expenditures for segment assets $ 191,541 $ 36,621 $ — $ 228,162 2016 Real Estate Observatory Intersegment Elimination Total Revenues: Rental revenue $ 460,653 $ — $ — $ 460,653 Intercompany rental revenue 75,658 — (75,658 ) — Tenant expense reimbursement 73,459 — — 73,459 Observatory revenue — 124,814 — 124,814 Lease termination fees 7,676 — — 7,676 Third-party management and other fees 1,766 — — 1,766 Other revenue and fees 8,970 15 — 8,985 Total revenues 628,182 124,829 (75,658 ) 677,353 Operating expenses: Property operating expenses 153,850 — — 153,850 Intercompany rent expense — 75,658 (75,658 ) — Ground rent expense 9,326 — — 9,326 General and administrative expenses 49,078 — — 49,078 Observatory expenses — 29,833 — 29,833 Real estate taxes 96,061 — — 96,061 Acquisition expenses 98 — — 98 Depreciation and amortization 154,817 394 — 155,211 Total operating expenses 463,230 105,885 (75,658 ) 493,457 Total operating income (loss) 164,952 18,944 — 183,896 Other income (expense): Interest income 647 — — 647 Interest expense (70,595 ) — — (70,595 ) Loss on early extinguishment of debt (552 ) — — (552 ) Income (loss) before income taxes 94,452 18,944 — 113,396 Income tax expense (1,361 ) (4,785 ) — (6,146 ) Net income $ 93,091 $ 14,159 $ — $ 107,250 Segment assets $ 3,641,844 $ 249,109 $ — $ 3,890,953 Expenditures for segment assets $ 197,680 $ — $ — $ 197,680

Summary of Quarterly Financial

Summary of Quarterly Financial Information (unaudited)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Summary of Quarterly Financial Information (unaudited)	Summary of Quarterly Financial Information (unaudited) The quarterly results of operations of our company for the years ended December 31, 2018 , 2017 and 2016 are as follows (amounts in thousands): March 31, 2018 June 30, 2018 September 30, 2018 December 31, 2018 Revenues $ 167,271 $ 178,529 $ 186,402 $ 199,309 Operating income $ 34,164 $ 49,665 $ 48,538 $ 58,490 Net income $ 18,058 $ 30,184 $ 29,230 $ 39,781 Net income attributable to common stockholders $ 9,768 $ 16,651 $ 16,342 $ 22,842 Net income per share attributable to common stockholders: Basic and diluted $ 0.06 $ 0.10 $ 0.10 $ 0.13 March 31, 2017 June 30, 2017 September 30, 2017 December 31, 2017 Revenues $ 164,333 $ 176,349 $ 186,547 $ 182,297 Operating income $ 36,045 $ 50,659 $ 56,008 $ 50,191 Net income $ 19,145 $ 31,359 $ 35,489 $ 32,260 Net income attributable to common stockholders $ 9,985 $ 16,584 $ 18,806 $ 17,272 Net income per share attributable to common stockholders: Basic and diluted $ 0.06 $ 0.10 $ 0.12 $ 0.11 March 31, 2016 June 30, 2016 September 30, 2016 December 31, 2016 Revenues $ 157,057 $ 165,785 $ 175,704 $ 178,807 Operating income $ 34,097 $ 44,162 $ 53,442 $ 52,195 Net income $ 16,705 $ 24,640 $ 32,897 $ 33,008 Net income attributable to common stockholders $ 7,428 $ 11,089 $ 15,973 $ 16,966 Net income per share attributable to common stockholders: Basic and diluted $ 0.06 $ 0.09 $ 0.12 $ 0.11

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2018
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events None.

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2018
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Schedule II - Valuation and Qualifying Accounts	Schedule II—Valuation and Qualifying Accounts (amounts in thousands) Description Balance At Additions Uncollectible Balance Year ended December 31, 2018 Allowance for doubtful accounts $ 1,607 $ (811 ) $ (289 ) $ 507 Year ended December 31, 2017 Allowance for doubtful accounts $ 3,723 $ (1,650 ) $ (466 ) $ 1,607 Year ended December 31, 2016 Allowance for doubtful accounts $ 3,037 $ 908 $ (222 ) $ 3,723

Schedule III - Real Estate and

Schedule III - Real Estate and Accumulated Depreciation	12 Months Ended
	Dec. 31, 2018
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Abstract]
Schedule III - Real Estate and Accumulated Depreciation	Schedule III—Real Estate and Accumulated Depreciation (amounts in thousands) Initial Cost to Cost Capitalized Gross Amount at Development Type Encumbrances Land Building & Improvements Carrying Land Buildings & Total Accumulated Date of Date Life on 111 West 33rd Street, New York, NY office / $ — $ 13,630 $ 244,461 $ 106,780 n/a $ 13,630 $ 351,241 $ 364,871 $ (41,629 ) 1954 2014 various 1400 Broadway, New York, NY office / — — 96,338 40,261 — — 136,599 136,599 (31,601 ) 1930 2014 various 1333 Broadway, New York, NY office / 158,484 91,435 120,190 7,491 n/a 91,435 127,681 219,116 (22,331 ) 1915 2013 various 1350 Broadway, New York, NY office / — — 102,518 27,161 — — 129,679 129,679 (25,312 ) 1929 2013 various 250 West 57th Street, New York, NY office/ — 2,117 5,041 141,581 n/a 2,117 146,622 148,739 (36,058 ) 1921 1953 various 501 Seventh Avenue, New York, NY office/ — 1,100 2,600 94,778 n/a 1,100 97,378 98,478 (43,164 ) 1923 1950 various 1359 Broadway, New York, NY office/ — 1,233 1,809 57,938 n/a 1,233 59,747 60,980 (26,549 ) 1924 1953 various 350 Fifth Avenue (Empire State Building), New York, NY office/ — 21,551 38,934 895,989 n/a 21,551 934,923 956,474 (211,068 ) 1930 2013 various One Grand Central Place, office/ — 7,240 17,490 241,218 n/a 7,222 258,726 265,948 (109,502 ) 1930 1954 various First Stamford Place, Stamford, CT office 178,616 22,952 122,739 63,292 n/a 24,862 184,121 208,983 (78,570 ) 1986 2001 various One Station Place, Stamford, CT (Metro Center) office 91,592 5,313 28,602 15,301 n/a 5,313 43,903 49,216 (30,763 ) 1987 1984 various 383 Main Avenue, Norwalk, CT office 29,614 2,262 12,820 22,253 n/a 2,262 35,073 37,335 (12,876 ) 1985 1994 various 500 Mamaroneck Avenue, Harrison, NY office — 4,571 25,915 22,198 n/a 4,571 48,113 52,684 (23,147 ) 1987 1999 various 10 Bank Street, White Plains, NY office 33,316 5,612 31,803 18,412 n/a 5,612 50,215 55,827 (21,134 ) 1989 1999 various 10 Union Square, New York, NY retail 49,116 5,003 12,866 1,966 n/a 5,003 14,832 19,835 (7,801 ) 1987 1996 various 1542 Third Avenue, New York, NY retail 29,459 2,239 15,266 425 n/a 2,239 15,691 17,930 (7,774 ) 1991 1999 various 1010 Third Avenue, New York, NY and 77 West 55th Street, New York, NY retail 38,370 4,462 15,817 783 n/a 4,462 16,600 21,062 (8,590 ) 1962 1998 various 69-97 Main Street, Westport, CT retail — 2,782 15,766 1,046 n/a 2,782 16,812 19,594 (7,113 ) 1922 2003 various 103-107 Main Street, Westport, CT retail — 1,243 7,043 321 n/a 1,260 7,347 8,607 (2,322 ) 1900 2006 various Property for development at the Transportation Hub in Stamford, CT land — 4,542 — 7,987 — 12,529 — 12,529 — n/a n/a n/a Totals $ 608,567 $ 199,287 $ 918,018 $ 1,767,181 $ — $ 209,183 $ 2,675,303 $ 2,884,486 $ (747,304 ) Empire State Realty Trust, Inc. Notes to Schedule III—Real Estate and Accumulated Depreciation (amounts in thousands) 1 . Reconciliation of Investment Properties The changes in our investment properties for the years ended December 31, 2018, 2017 and 2016 are as follows: 2018 2017 2016 Balance, beginning of year $ 2,667,655 $ 2,458,629 $ 2,276,330 Acquisition of new properties — — — Improvements 256,496 228,162 197,680 Disposals (39,665 ) (19,136 ) (15,381 ) Balance, end of year $ 2,884,486 $ 2,667,655 $ 2,458,629 The unaudited aggregate cost of investment properties for federal income tax purposes as of December 31, 2018 was $2.5 billion . 2 . Reconciliation of Accumulated Depreciation The changes in our accumulated depreciation for the years ended December 31, 2018, 2017 and 2016 are as follows: 2018 2017 2016 Balance, beginning of year $ 656,900 $ 556,546 $ 465,584 Depreciation expense 130,069 119,490 106,343 Disposals (39,665 ) (19,136 ) (15,381 ) Balance, end of year $ 747,304 $ 656,900 $ 556,546 Depreciation of investment properties reflected in the combined statements of income is calculated over the estimated original lives of the assets as follows: Buildings 39 years Building improvements 39 years or useful life Tenant improvements Term of related lease

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”) and with the rules and regulations of the Securities and Exchange Commission (the "SEC") represent our assets and liabilities and operating results. The consolidated financial statements include our accounts and our wholly owned subsidiaries as well as our operating partnership and its subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation.
Consolidation, Variable Interest Entity	We consolidate entities in which we have a controlling financial interest. In determining whether we have a controlling financial interest in a partially owned entity and the requirement to consolidate the accounts of that entity, we consider factors such as ownership interest, board representation, management representation, authority to make decisions, and contractual and substantive participating rights of the partners/members as well as whether the entity is a variable interest entity (“VIE”) and we are the primary beneficiary. The primary beneficiary of a VIE is the entity that has (i) the power to direct the activities that most significantly impact the entity's economic performance and (ii) the obligation to absorb losses of the VIE or the right to receive benefits from the VIE that could be significant to the VIE. The primary beneficiary is required to consolidate the VIE. Our operating partnership, Empire State Realty OP, L.P., is a variable interest entity of our company, Empire State Realty Trust, Inc. As the operating partnership is already consolidated in the financial statements of Empire State Realty Trust, Inc., the identification of this entity as a variable interest entity had no impact on our consolidated financial statements. We will assess the accounting treatment for each investment we may have in the future. This assessment will include a review of each entity’s organizational agreement to determine which party has what rights and whether those rights are protective or participating. For all VIEs, we will review such agreements in order to determine which party has the power to direct the activities that most significantly impact the entity’s economic performance and benefit. In situations where we or our partner could approve, among other things, the annual budget, or leases that cover more than a nominal amount of space relative to the total rentable space at each property, we would not consolidate the investment as we consider these to be substantive participation rights that result in shared power of the activities that would most significantly impact the performance and benefit of such joint venture investment. A non-controlling interest in a consolidated subsidiary is defined as the portion of the equity (net assets) in a subsidiary not attributable, directly or indirectly, to a parent. Non-controlling interests are required to be presented as a separate component of equity in the consolidated balance sheets and in the consolidated statements of income by requiring earnings and other comprehensive income to be attributed to controlling and non-controlling interests.
Accounting Estimates	Accounting Estimates The preparation of the consolidated financial statements in accordance with GAAP requires management to use estimates and assumptions that in certain circumstances affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities, and the reported revenues and expenses. Significant items subject to such estimates and assumptions include allocation of the purchase price of acquired real estate properties among tangible and intangible assets, determination of the useful life of real estate properties and other long-lived assets, valuation and impairment analysis of commercial real estate properties and other long-lived assets, estimate of tenant expense reimbursements, estimate of percentage of completion on construction contracts, valuation of the allowance for doubtful accounts, and valuation of derivative instruments, senior unsecured notes, mortgage notes payable, unsecured notes, unsecured revolving credit and term loan facilities, and equity based compensation. These estimates are prepared using management’s best judgment, after considering past, current, and expected events and economic conditions. Actual results could differ from those estimates.
Revenue Recognition	Revenue Recognition Rental Revenue Rental revenue includes base rents that each tenant pays in accordance with the terms of its respective lease and is reported on a straight-line basis over the non-cancellable term of the lease which includes the effects of rent steps and rent abatements under the leases. In general, we commence rental revenue recognition when the tenant takes possession of the leased space or controls the physical use of the leased space and the leased space is substantially ready for its intended use. We account for all of our leases as operating leases. Deferred rent receivables, including free rental periods and leasing arrangements allowing for increased base rent payments, are accounted for in a manner that provides an even amount of fixed lease revenues over the respective non-cancellable lease terms. Differences between rental income recognized and amounts due under the respective lease agreements are recognized as an increase or decrease to deferred rent receivables. In addition to base rent, our tenants also generally will pay their pro rata share of increases in real estate taxes and operating expenses for the building over a base year. In some leases, in lieu of paying additional rent based upon increases in building operating expenses, the tenant will pay additional rent based upon increases in an index such as the Consumer Price Index over the index value in effect during a base year, or contain fixed percentage increases over the base rent to cover escalations. We will recognize rental revenue of acquired in-place above- and below-market leases at their fair values over the terms of the respective leases, including, for below-market leases, fixed option renewal periods, if any. Lease termination fees are recognized when the fees are determinable, tenant vacancy has occurred, collectability is reasonably assured, we have no continuing obligation to provide services to such former tenants and the payment is not subject to any conditions that must be met or waived. Observatory Revenue Revenues from the sale of Observatory tickets are recognized upon admission or ticket expirations. Deferred revenue related to unused and unexpired tickets as of December 31, 2018 and 2017 was $4.1 million and $4.1 million , respectively, and is included in deferred revenue and other liabilities on the consolidated balance sheets. Gains on Sale of Real Estate We record a gain on sale of real estate when title is conveyed to the buyer and we have no substantial economic involvement with the property. If the sales criteria for the full accrual method are not met, we defer some or all of the gain recognition and account for the continued operations of the property by applying the finance, leasing, profit sharing, deposit, installment or cost recovery methods, as appropriate, until the sales criteria are met. Third-Party Management and Other Fees We earn revenue arising from contractual agreements with related party entities for asset and property management services. This revenue is recognized as the related services are performed under the respective agreements in place.
Other Revenue and Fees	Other Revenues and Fees Other revenues and fees includes parking income, percentage rent, legal, tax and insurance settlements, demand response energy use earnings and sales from our restaurant at the Empire State Building.
Advertising and Marketing Costs	Advertising and Marketing Costs Advertising and marketing costs are expensed as incurred.
Real Estate Properties and Related Intangible Assets	Real Estate Properties and Related Intangible Assets Land and buildings and improvements are recorded at cost less accumulated depreciation and amortization. The recorded cost includes cost of acquisitions, development and construction and tenant allowances and improvements. Expenditures for ordinary repairs and maintenance are charged to property operating expense as incurred. Significant replacements and betterments which improve or extend the life of the asset are capitalized. Tenant improvements which improve or extend the life of the asset are capitalized. If a tenant vacates its space prior to the contractual termination of its lease, the unamortized balance of any tenant improvements are written off if they are replaced or have no future value. For developed properties, direct and indirect costs that clearly relate to projects under development are capitalized. Costs include construction costs, professional services such as architectural and legal costs, capitalized interest and direct payroll costs. We begin capitalization when the project is probable. The assets relating to the project are stated at cost and are not depreciated. Once construction is completed and the assets are placed in service, the assets are reclassified to the appropriate asset class and depreciated in accordance with the useful lives as indicated below. Capitalization of interest ceases when the asset is ready for its intended use, which is generally near the date that a certificate of occupancy is obtained. Total capitalized interest for the years ended December 31, 2018 and 2017 was $1.6 million and $0.5 million , respectively. There was no capitalized interest for the year ended December 31, 2016. Depreciation and amortization are computed using the straight-line method for financial reporting purposes. Buildings and improvements are depreciated over the shorter of 39 years, the useful life, or the remaining term of any leasehold interest. Tenant improvement costs, which are included in building and improvements in the consolidated balance sheets, are depreciated over the shorter of (i) the related remaining lease term or (ii) the life of the improvement. Corporate equipment, which is included in “Other assets,” is depreciated over three to seven years. Acquisitions of properties are accounted for utilizing the acquisition method and accordingly the purchase cost is allocated to tangible and intangible assets and liabilities based on their fair values. The fair value of tangible assets acquired is determined by valuing the property as if it were vacant, applying methods similar to those used by independent appraisers of income-producing property. The resulting value is then allocated to land, buildings and improvements, and tenant improvements based on our determination of the fair value of these assets. The assumptions used in the allocation of fair values to assets acquired are based on our best estimates at the time of evaluation. Fair value is assigned to above-market and below-market leases based on the difference between (a) the contractual amounts to be paid by the tenant based on the existing lease and (b) our estimate of current market lease rates for the corresponding in-place leases, over the remaining terms of the in-place leases. Capitalized above-market lease amounts are amortized as a decrease to rental revenue over the remaining terms of the respective leases. Capitalized below-market lease amounts are amortized as an increase to rental revenue over the remaining terms of the respective leases. If a tenant vacates its space prior to the contractual termination of the lease and no rental payments are being made on the lease, any unamortized balance of the related intangible will be written off. The aggregate value of other acquired intangible assets consists of acquired ground leases and acquired in-place leases and tenant relationships. The fair value allocated to acquired in-place leases consists of a variety of components including, but not necessarily limited to: (a) the value associated with avoiding the cost of originating the acquired in-place leases (i.e. the market cost to execute a lease, including leasing commissions and legal fees, if any); (b) the value associated with lost revenue related to tenant reimbursable operating costs estimated to be incurred during the assumed lease-up period (i.e. real estate taxes, insurance and other operating expenses); (c) the value associated with lost rental revenue from existing leases during the assumed lease-up period; and (d) the value associated with any other inducements to secure a tenant lease. We assess the potential for impairment of our long-lived assets, including real estate properties, annually or whenever events occur or a change in circumstances indicate that the recorded value might not be fully recoverable. We determine whether impairment in value has occurred by comparing the estimated future undiscounted cash flows expected from the use and eventual disposition of the asset to its carrying value. If the undiscounted cash flows do not exceed the carrying value, the real estate is adjusted to fair value and an impairment loss is recognized. Assets held for sale are recorded at the lower of cost or fair value less costs to sell. We do not believe that the value of any of our properties and intangible assets were impaired during the years ended December 31, 2018, 2017 and 2016.
Cash and Cash Equivalents and Restricted Cash	Cash and Cash Equivalents Cash and cash equivalents consist of cash on hand, government money markets, demand deposits with financial institutions and short-term liquid investments with original maturities of three months or less when purchased. Cash and cash equivalents held at major commercial banks may at times exceed the Federal Deposit Insurance Corporation limit. To date, we have not experienced any losses on our invested cash. Restricted Cash Restricted cash consists of amounts held for tenants in accordance with lease agreements such as security deposits and amounts held by lenders and/or escrow agents to provide for future real estate tax expenditures and insurance expenditures, tenant vacancy related costs and debt service obligations.
Short-term Investments	Short-term Investments Short-term investments include time deposits with original maturities of greater than three months and remaining maturities of less than one year.
Tenant and Other Receivables	Tenant and Other Receivables Tenant and other receivables, other than deferred rent receivable, are generally expected to be collected within one year.
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts We maintain an allowance against tenant and other receivables and deferred rents receivables for future potential tenant credit losses. The credit assessment is based on the estimated accrued rental revenue that is recoverable over the term of the respective lease. The computation of this allowance is based on the tenants’ payment history and current credit status. If our estimate of collectability differs from the cash received, then the timing and amount of our reported revenue could be impacted. Bad debt expense is included in operating expenses on our consolidated statements of income and includes the impact of changes in the allowance for doubtful accounts on our consolidated balance sheets.
Deferred Leasing Costs and Deferred Financing Costs	Deferred Leasing Costs Deferred leasing costs consist of fees and direct costs incurred to initiate and renew leases, are amortized on a straight-line basis over the related lease term and the expense is included in depreciation and amortization in our consolidated statements of income. Upon the early termination of a lease, unamortized deferred leasing costs are charged to expense. Deferred Financing Costs Fees and costs incurred to obtain long-term financing have been deferred and are amortized as a component of interest expense in our consolidated statements of income over the life of the respective long-term financing on the straight-line method which approximates the effective interest method. Unamortized deferred financing costs are expensed when the associated debt is refinanced or repaid before maturity. Costs incurred in seeking debt, which do not close, are expensed in the period in which it is determined that the financing will not close.
Equity Method Investments	Equity Method Investments We account for investments under the equity method of accounting where we do not have control but have the ability to exercise significant influence. Under this method, investments are recorded at cost, and the investment accounts are adjusted for our share of the entities’ income or loss and for distributions and contributions. Equity income (loss) is allocated based on the portion of the ownership interest that is controlled by us. The agreements may designate different percentage allocations among investors for profits and losses; however, our recognition of the entity’s income or loss generally follows the entity’s distribution priorities, which may change upon the achievement of certain investment return thresholds. To the extent that we contributed assets to an entity, our investment in the entity is recorded at cost basis in the assets that were contributed to the entity. Upon contributing assets to an entity, we make a judgment as to whether the economic substance of the transaction is a sale. If so, gain or loss is recognized on the portion of the asset to which the other partners in the entity obtain an interest. To the extent that the carrying amount of these investments on our combined balance sheets is different than the basis reflected at the entity level, the basis difference would be amortized over the life of the related asset and included in our share of equity in net income of the entity. On a periodic basis, we assess whether there are any indicators that the carrying value of our investments in entities may be impaired on an other than temporary basis. An investment is impaired only if management’s estimate of the fair value of the investment is less than the carrying value of the investment on an other than temporary basis. To the extent impairment has occurred, the loss shall be measured as the excess of the carrying value of the investment over the fair value of the investment. As of December 31, 2018 and 2017, we had no equity method investments.
Goodwill	Goodwill Goodwill is tested annually for impairment and is tested for impairment more frequently if events and circumstances indicate that the asset might be impaired. An impairment loss is recognized to the extent that the carrying amount, including goodwill, exceeds the reporting unit’s fair value and the implied fair value of goodwill is less than the carrying amount of that goodwill. Non-amortizing intangible assets, such as trade names and trademarks, are subject to an annual impairment test based on fair value and amortizing intangible assets are tested whenever events or changes in circumstances indicate that the carrying amount may not be recoverable.
Fair Value	Fair Value Fair value is a market-based measurement, not an entity-specific measurement, and should be determined based on the assumptions that market participants would use in pricing the asset or liability. As a basis for considering market participant assumptions in fair value measurements, the Financial Accounting Standards Board ("FASB") guidance establishes a fair value hierarchy that distinguishes between market participant assumptions based on market data obtained from sources independent of the reporting entity (observable inputs that are classified within levels one and two of the hierarchy) and the reporting entity's own assumptions about market participant assumptions (unobservable inputs classified within Level 3 of the hierarchy). The methodologies used for valuing financial instruments have been categorized into three broad levels as follows: Level 1 - Quoted prices in active markets for identical instruments. Level 2 - Valuations based principally on other observable market parameters, including: • Quoted prices in active markets for similar instruments; • Quoted prices in less active or inactive markets for identical or similar instruments; • Other observable inputs (such as risk free interest rates, yield curves, volatilities, prepayment speeds, loss severities, credit risks and default rates); and • Market corroborated inputs (derived principally from or corroborated by observable market data). Level 3 - Valuations based significantly on unobservable inputs, including: • Valuations based on third-party indications (broker quotes or counterparty quotes) which were, in turn, based significantly on unobservable inputs or were otherwise not supportable; and • Valuations based on internal models with significant unobservable inputs. These levels form a hierarchy. We follow this hierarchy for our financial instruments measured or disclosed at fair value on a recurring and nonrecurring basis and other required fair value disclosures. The classifications are based on the lowest level of input that is significant to the fair value measurement. We use the following methods and assumptions in estimating fair value disclosures for financial instruments. Cash and cash equivalents, restricted cash, short term investments, tenant and other receivables, prepaid expenses and other assets, deferred revenue, tenant security deposits, accounts payable and accrued expenses carrying values approximate their fair values due to the short term maturity of these instruments. The fair value of our senior unsecured notes - exchangeable was derived from quoted prices in active markets and is classified as Level 2 since trading volumes are low. The fair value of derivative instruments is determined using widely accepted valuation techniques, including discounted cash flow analysis on the expected cash flows of each derivative. Although the majority of the inputs used to value our derivatives fall within Level 2 of the fair value hierarchy, the credit valuation adjustments associated with our derivatives utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default by ourselves and our counterparties. The impact of such credit valuation adjustments, determined based on the fair value of each individual contract, was not significant to the overall valuation. As a result, all of our derivatives were classified as Level 2 of the fair value hierarchy. The fair value of our mortgage notes payable, unsecured revolving credit and term loan facility, and senior unsecured notes - Series A, B, C, D, E and F which are determined using Level 3 inputs, are estimated by discounting the future cash flows using current interest rates at which similar borrowings could be made to us.
Derivative Instruments	Derivative Instruments We are exposed to the effect of interest rate changes and manage these risks by following policies and procedures including the use of derivatives. To manage exposure to interest rates, derivatives are used primarily to fix the rate on debt based on floating-rate indices. We also hedge exposure to the variability in future cash flows for forecast transactions over a maximum period of 11 months (excluding forecast transactions related to the payment of variable interest on existing financial instruments). We record all derivatives on the balance sheet at fair value. We incorporate credit valuation adjustments to appropriately reflect both our own nonperformance risk and the respective counterparty’s nonperformance risk in the fair value measurements. We measure the credit risk of our derivative instruments that are subject to master netting agreements on a net basis by counterparty portfolio. For derivatives that qualify as cash flow hedges, we report the gain or loss on the derivative designated as a hedge as part of other comprehensive income (loss) and subsequently reclassify the gain or loss into income in the period that the hedged transaction affects income.
Income Taxes	Income Taxes We elected to be taxed as a REIT under sections 856 through 860 of the Internal Revenue Code of 1986, as amended, (the "Code"), commencing with the taxable year ended December 31, 2013 and believe we qualify as a REIT at December 31, 2018. REITs are subject to a number of organizational and operational requirements, including a requirement that 90% of ordinary “REIT taxable income” (as determined without regard to the dividends paid deduction or net capital gains) be distributed. As a REIT, we will generally not be subject to U.S. federal income tax to the extent that we meet the organizational and operational requirements and our distributions equal or exceed REIT taxable income. For all periods subsequent to the effective date of our REIT election, we have met the organizational and operational requirements and distributions have exceeded net taxable income. Accordingly, no provision has been made for federal and state income taxes. We have elected to treat ESRT Observatory TRS, L.L.C., our subsidiary which holds our observatory operations, and ESRT Holdings TRS, L.L.C., our subsidiary that holds our third party management, restaurant, cafeteria, health clubs and certain cleaning operations, as taxable REIT subsidiaries. Taxable REIT subsidiaries may participate in non-real estate activities and/or perform non-customary services for tenants and their operations are generally subject to regular corporate income taxes. Our taxable REIT subsidiaries accounts for its income taxes in accordance with GAAP, which includes an estimate of the amount of taxes payable or refundable for the current year and deferred tax liabilities and assets for the future tax consequences of events that have been recognized in our financial statements or tax returns. The calculation of the taxable REIT subsidiaries' tax provisions may require interpreting tax laws and regulations and could result in the use of judgments or estimates which could cause its recorded tax liability to differ from the actual amount due. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The taxable REIT subsidiaries periodically assess the realizability of deferred tax assets and the adequacy of deferred tax liabilities, including the results of local, state, or federal statutory tax audits or estimates and judgments used. We apply provisions for measuring and recognizing tax benefits associated with uncertain income tax positions. Penalties and interest, if incurred, would be recorded as a component of income tax expense. As of December 31, 2018 and 2017, we do not have a liability for uncertain tax positions. As of December 31, 2018 , the tax years ended December 31, 2015 through December 31, 2018 remain open for an audit by the Internal Revenue Service, state or local authorities.
Share-Based Compensation	Share-Based Compensation Share-based compensation is measured at the fair value of the award on the date of grant and recognized as an expense on a straight-line basis over the vesting period. The determination of fair value of these awards is subjective and involves significant estimates and assumptions including expected volatility of our stock, expected dividend yield, expected term, and assumptions of whether these awards will achieve parity with other operating partnership units or achieve performance thresholds. We believe that the assumptions and estimates utilized are appropriate based on the information available to management at the time of grant.
Per Share Data	Per Share Data Basic and diluted earnings per share are computed based upon the weighted average number of shares outstanding during the respective period.
Segment Reporting	Segment Reporting We have identified two reportable segments: (1) Real Estate and (2) Observatory. Our real estate segment includes all activities related to the ownership, management, operation, acquisition, repositioning and disposition of our real estate assets. Our observatory segment operates the 86th and 102nd floor observatories at the Empire State Building. These two lines of businesses are managed separately because each business requires different support infrastructures, provides different services and has dissimilar economic characteristics such as investments needed, stream of revenues and different marketing strategies. We account for intersegment sales and rent as if the sales or rent were to third parties, that is, at current market prices.
Reclassification	Reclassification Certain prior year balances have been reclassified to conform to our current year presentation. The 2017 and 2016 balance of other revenues and fees has been reclassified to separately present lease termination fees and interest income and conform to our current year presentation.
Recently Issued or Adopted Accounting Standards	Recently Issued or Adopted Accounting Standards During August 2018, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (a consensus of the FASB Emerging Issues Task Force), which contain amendments that align the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal use software license). Accordingly, for entities in a hosting arrangement that is a service contract, costs for implementation activities in the application development stage are capitalized depending on the nature of the costs, while costs incurred during the preliminary project and post-implementation stages are expensed as the activities are performed. The amendments in ASU No. 2018-15 also require the entity (customer) to expense the capitalized implementation costs of a hosting arrangement that is a service contract over the term of the hosting arrangement. The amendments are effective for public business entities for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Early adoption of the amendments is permitted, including adoption in any interim period. The amendments in ASU No. 2018-15 should be applied either retrospectively or prospectively to all implementation costs incurred after the date of adoption. We are evaluating the impact of adopting this new accounting standard on our consolidated financial statements. During January 2017, the FASB issued ASU No. 2017-04, Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment, which contain amendments that modify the concept of impairment from the condition that exists when the carrying amount of goodwill exceeds its implied fair value to the condition that exists when the carrying amount of a reporting unit exceeds its fair value. An entity no longer will determine goodwill impairment by calculating the implied fair value of goodwill by assigning the fair value of a reporting unit to all of its assets and liabilities as if that reporting unit had been acquired in a business combination. Because these amendments eliminate Step 2 from the goodwill impairment test, they should reduce the cost and complexity of evaluating goodwill for impairment. ASU No. 2017-04 should be applied on a prospective basis and the amendments adopted for the annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. We are evaluating the impact of adopting this new accounting standard on our consolidated financial statements. During January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business, which contain amendments to clarify the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The amendments in ASU No. 2017-01 provide a screen to determine when an integrated set of assets and activities (collectively referred to as a “set”) is not a business. The screen requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. This screen reduces the number of transactions that need to be further evaluated. If the screen is not met, the amendments (1) require that to be considered a business, a set must include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create output and (2) remove the evaluation of whether a market participant could replace missing elements. The amendments provide a framework to assist entities in evaluating whether both an input and a substantive process are present. Additionally, these amendments narrow the definition of the term output so that the term is consistent with how outputs are described in Topic 606, Revenue from Contracts with Customers. ASU No. 2017-01 will be effective for annual periods beginning after December 15, 2017, including interim periods within those periods. The amendments should be applied prospectively on or after the effective date. No disclosures are required at transition. We believe that future acquisitions of real estate properties will be considered asset acquisitions. During November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash, which contain amendments that require that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. Therefore, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. ASU No. 2016-18 will be effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. The amendments should be applied using a retrospective transition method to each period presented. We adopted this standard on January 1, 2018 using a retrospective transition method. The adoption did not have a material impact on our consolidated financial statements. During August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments, which addresses eight specific cash flow issues with the objective of reducing the existing diversity in practice in how certain cash receipts and cash payments are presented and classified in the statement of cash flows. ASU No. 2016-15 will be effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Earlier adoption is permitted including adoption in an interim period. We adopted this standard on January 1, 2018 using a retrospective transition method. The adoption did not have a material impact on our consolidated financial statements. During June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which contains amendments that replace the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. During November 2018, the FASB issued ASU No. 2018-19 Codification Improvements to Topic 326, Financial Instruments—Credit Losses which contain amendments relating to the transition and effective date requirements for nonpublic business entities and also clarified that receivables arising from operating leases are not within the scope of Subtopic 326-20, Financial Instruments—Credit Losses—Measured at Amortized Cost. ASU No. 2016-13 and ASU No. 2018-19 will be effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Earlier adoption as of the fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, is permitted. The amendments must be adopted through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective (that is, a modified retrospective approach). We are evaluating the impact of adopting this new accounting standard on our consolidated financial statements. During February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which requires that a lessee recognize in the statement of financial position a liability to make lease payments (the lease liability) and a right-of-use asset representing its right to use the underlying asset for the lease term. For leases with a term of 12 months or less, a lessee is permitted to make an accounting policy election by class of underlying asset not to recognize lease assets and lease liabilities. ASU No. 2016-02 leaves the accounting for leases by lessors largely unchanged from previous GAAP. ASU No. 2016-02 will be effective for fiscal years beginning after December 15, 2018 and subsequent interim periods. The new standard must be adopted using a modified retrospective transition, and provides for certain practical expedients. Transition will require application of the new guidance at the beginning of the earliest comparative period presented. This ASU is expected to result in the recognition of a right-to-use asset and related liability to account for our future obligations under our ground lease agreements for which we are the lessee. As of December 31, 2018, the remaining contractual payments under our ground lease agreements aggregated $75.9 million . In addition, under ASU 2016-02, lessors may only capitalize incremental direct leasing costs. As a result, we expect that we will no longer capitalize our non-contingent leasing costs and instead will expense these costs as incurred. These costs totaled $4.6 million for the year ended December 31, 2018. During July 2018, the FASB issued ASU No. 2018-10, Codification Improvements to Topic 842, Leases, which contains amendments which are intended to clarify or to correct unintended application of ASU No. 2016-02. Also during July 2018, the FASB issued ASU No. 2018-11, Targeted Improvements to Topic 842, Leases, which provides another transition method in addition to the existing modified retrospective transition method by allowing a cumulative effect adjustment to the opening balance of retained earnings in the period of adoption. The amendments in ASU No. 2018-11 also provide lessors with a practical expedient, by class of underlying asset, to not separate nonlease components from the associated lease component provided that (1) the timing and pattern of transfer are the same for the nonlease components and associated lease component and (2) the lease component, if accounted separately, would be classified as an operating lease. During December 2018, the FASB issued ASU No. 2018-20, Narrow-Scope Improvements for Lessors that contain amendments to further help lessors apply ASU No. 2016-02, including amendments that require lessors to (1) exclude lessor costs paid directly by lessees to third parties on the lessor's behalf from variable payments and therefore variable lease revenue and (2) include lessor costs that are paid by the lessor and reimbursed by the lessee in the measurement of variable lease revenue and the associated expense. For entities that have not yet adopted ASU No. 2016-02, the effective dates and transition requirements for ASU No. 2018-10, ASU No. 2018-11 and ASU No. 2018-20 will be the same as the effective date and transition requirements in ASU No. 2016-02. We adopted this standard on January 1, 2019 and elected the available practical expedients. ASU 2016-02 and its related amendments resulted in the recognition of right-of-use assets and lease liabilities for our operating leases on our balance sheet of approximately $30.0 million , but did not have an impact on our consolidated statements of income. During May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which replaces all current GAAP guidance related to revenue recognition and eliminates all industry-specific guidance. The new revenue recognition standard provides a unified model to determine when and how revenue is recognized. The core principle is that a company should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. We adopted this standard on January 1, 2018 and it did not have a material impact on our consolidated financial statements.

Deferred Costs, Acquired Leas_2

Deferred Costs, Acquired Lease Intangibles and Goodwill (Tables)	12 Months Ended
	Dec. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Schedule of Deferred Costs, Net	Deferred costs, net, consisted of the following at December 31, 2018 and 2017 (amounts in thousands): 2018 2017 Leasing costs $ 178,120 $ 164,751 Acquired in-place lease value and deferred leasing costs 214,550 237,364 Acquired above-market leases 52,136 67,415 444,806 469,530 Less: accumulated amortization (209,839 ) (215,102 ) Total deferred costs, net, excluding net deferred financing costs $ 234,967 $ 254,428 Deferred financing costs, net, consisted of the following at December 31, 2018 and 2017 (amounts in thousands): 2018 2017 Financing costs $ 25,315 $ 24,446 Less: accumulated amortization (10,027 ) (7,039 ) Total deferred financing costs, net $ 15,288 $ 17,407
Schedule of Amortizing Acquired Intangible Assets and Liabilities	Amortizing acquired intangible assets and liabilities consisted of the following at December 31, 2018 and 2017 (amounts in thousands): 2018 2017 Acquired below-market ground leases $ 396,916 $ 396,916 Less: accumulated amortization (36,518 ) (28,687 ) Acquired below-market ground leases, net $ 360,398 $ 368,229 2018 2017 Acquired below-market leases $ (118,462 ) $ (132,026 ) Less: accumulated amortization 66,012 65,979 Acquired below-market leases, net $ (52,450 ) $ (66,047 )
Schedule of Future Amortization Expense and Rental Revenue from Acquired Intangible Assets	We expect to recognize amortization expense and rental revenue from the acquired intangible assets and liabilities as follows (amounts in thousands): For the year ending: Future Ground Rent Amortization Future Amortization Expense Future Rental Revenue 2019 $ 7,831 $ 15,829 $ 6,875 2020 7,831 12,967 3,651 2021 7,831 11,250 2,868 2022 7,831 10,433 3,185 2023 7,831 9,756 3,181 Thereafter 321,243 31,690 9,532 $ 360,398 $ 91,925 $ 29,292

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Schedule of Debt	Debt consisted of the following as of December 31, 2018 and 2017 (amounts in thousands): As of December 31, 2018 Principal Balance as Principal Balance as Stated Effective (1) Maturity (2) Fixed rate mortgage debt Metro Center $ 91,838 $ 93,948 3.59 % 3.68 % 11/5/2024 10 Union Square 50,000 50,000 3.70 % 3.97 % 4/1/2026 1542 Third Avenue 30,000 30,000 4.29 % 4.53 % 5/1/2027 First Stamford Place (3) 180,000 180,000 4.28 % 4.45 % 7/1/2027 1010 Third Avenue and 77 West 55th Street 38,995 39,710 4.01 % 4.22 % 1/5/2028 10 Bank Street 33,779 34,602 4.23 % 4.35 % 6/1/2032 383 Main Avenue 30,000 30,000 4.44 % 4.55 % 6/30/2032 1333 Broadway 160,000 66,602 4.21 % 4.29 % 2/5/2033 1400 Broadway (first lien mortgage loan) — 66,632 — — — (second lien mortgage loan) — 9,172 — — — 111 West 33rd Street (first lien mortgage loan) — 74,045 — — — (second lien mortgage loan) — 9,369 — — — 1350 Broadway — 37,144 — — — Total mortgage debt 614,612 721,224 Senior unsecured notes - exchangeable 250,000 250,000 2.63 % 3.93 % 8/15/2019 Senior unsecured notes: (4) Series A 100,000 100,000 3.93 % 3.96 % 3/27/2025 Series B 125,000 125,000 4.09 % 4.12 % 3/27/2027 Series C 125,000 125,000 4.18 % 4.21 % 3/27/2030 Series D 115,000 115,000 4.08 % 4.11 % 1/22/2028 Series E 160,000 — 4.26 % 4.27 % 3/22/2030 Series F 175,000 — 4.44 % 4.45 % 3/22/2033 Unsecured revolving credit facility (4) — — (5) (5) 8/29/2021 Unsecured term loan facility (4) 265,000 265,000 (6) (6) 8/29/2022 Total principal 1,929,612 1,701,224 Unamortized (discount) premiums, net of unamortized premiums (discount) (1,647 ) (3,370 ) Deferred financing costs, net (9,032 ) (9,133 ) Total $ 1,918,933 $ 1,688,721 ______________ (1) The effective rate is the yield as of December 31, 2018, including the effects of debt issuance costs and the amortization of the fair value of debt adjustment. (2) Pre-payment is generally allowed for each loan upon payment of a customary pre-payment penalty. (3) Represents a $164 million mortgage loan bearing interest of 4.09% and a $16 million loan bearing interest at 6.25% . (4) At December 31, 2018, we were in compliance with all debt covenants. (5) At December 31, 2018, the unsecured revolving credit facility bears a floating rate at 30 day LIBOR plus 1.10% . The rate at December 31, 2018 was 3.60% . (6) The unsecured term loan facility bears a floating rate at 30 day LIBOR plus 1.20% . Pursuant to an interest rate swap agreement, the LIBOR rate is fixed at 2.1485% through maturity. The rate at December 31, 2018 was 3.35% .
Schedule of Maturities of Long-term Debt	Aggregate required principal payments at December 31, 2018 are as follows (amounts in thousands): Year Amortization Maturities Total 2019 $ 3,790 $ 250,000 $ 253,790 2020 3,938 — 3,938 2021 4,090 — 4,090 2022 5,628 265,000 270,628 2023 7,876 — 7,876 Thereafter 33,868 1,355,422 1,389,290 Total principal maturities $ 59,190 $ 1,870,422 $ 1,929,612
Schedule of Deferred Costs, Net	Deferred costs, net, consisted of the following at December 31, 2018 and 2017 (amounts in thousands): 2018 2017 Leasing costs $ 178,120 $ 164,751 Acquired in-place lease value and deferred leasing costs 214,550 237,364 Acquired above-market leases 52,136 67,415 444,806 469,530 Less: accumulated amortization (209,839 ) (215,102 ) Total deferred costs, net, excluding net deferred financing costs $ 234,967 $ 254,428 Deferred financing costs, net, consisted of the following at December 31, 2018 and 2017 (amounts in thousands): 2018 2017 Financing costs $ 25,315 $ 24,446 Less: accumulated amortization (10,027 ) (7,039 ) Total deferred financing costs, net $ 15,288 $ 17,407

Accounts Payable and Accrued _2

Accounts Payable and Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2018
Payables and Accruals [Abstract]
Schedule of Accounts Payable and Accrued Expenses	Accounts payable and accrued expenses consist of the following as of December 31, 2018 and 2017 (amounts in thousands): 2018 2017 Accrued capital expenditures $ 85,242 $ 71,769 Accounts payable and accrued expenses 34,585 32,509 Interest rate swap agreements liability 5,243 436 Accrued interest payable 4,990 5,687 Due to affiliated companies 616 448 Total accounts payable and accrued expenses $ 130,676 $ 110,849

Financial Instruments and Fai_2

Financial Instruments and Fair Values (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Summary of the Terms of Agreements and Fair Values of Derivative Financial Instruments	The table below summarizes the terms of agreements and the fair values of our derivative financial instruments as of December 31, 2018 and 2017 (dollar amounts in thousands): December 31, 2018 December 31, 2017 Derivative Notional Amount Receive Rate Pay Rate Effective Date Expiration Date Asset Liability Asset Liability Interest rate swap $ 265,000 1 Month LIBOR 2.1485 % August 31, 2017 August 24, 2022 $ 2,536 $ — $ — $ (436 ) Interest rate swap 125,000 3 Month LIBOR 2.9580 % July 1, 2019 July 1, 2026 — (2,623 ) — — Interest rate swap 125,000 3 Month LIBOR 2.9580 % July 1, 2019 July 1, 2026 — (2,620 ) — — $ 2,536 $ (5,243 ) $ — $ (436 )
Summary of Effect of Derivative Financial Instruments Designated as Cash Flow Hedges	The table below shows the effect of our derivative financial instruments designated as cash flow hedges on accumulated other comprehensive income (loss) for the years ended December 31, 2018, 2017 and 2016 (amounts in thousands): Effects of Cash Flow Hedges December 31, 2018 December 31, 2017 December 31, 2016 Amount of gain (loss) recognized in other comprehensive income (loss) $ (2,721 ) $ (11,658 ) $ (3,054 ) Amount of gain (loss) reclassified from accumulated other comprehensive income (loss) into interest expense (1,845 ) (1,142 ) — The table below shows the effect of our derivative financial instruments designated as cash flow hedges on the consolidated statements of income for the years ended December 31, 2018, 2017 and 2016 (amounts in thousands): Effects of Cash Flow Hedges December 31, 2018 December 31, 2017 December 31, 2016 Total interest (expense) presented on the consolidated statements of income in which the effects of cash flow hedges are recorded $ (79,623 ) $ (68,473 ) $ (70,595 ) Amount of gain (loss) reclassified from accumulated other comprehensive income (loss) into interest expense (1,845 ) (1,142 ) —
Schedule of the Aggregate Carrying Value of Debt and Estimates of Fair Value	The following tables summarize the carrying and estimated fair values of our financial instruments as of December 31, 2018 and 2017 (amounts in thousands): December 31, 2018 Carrying Value Estimated Fair Value Total Level 1 Level 2 Level 3 Interest rate swaps included in prepaid expenses and other assets $ 2,536 $ 2,536 $ — $ 2,536 $ — Interest rate swaps included in accounts payable and accrued expenses 5,243 5,243 — 5,243 — Mortgage notes payable 608,567 597,424 — — 597,424 Senior unsecured notes - Exchangeable 247,930 250,625 — 250,625 — Senior unsecured notes - Series A, B, C, D, E and F 798,289 795,662 — — 795,662 Unsecured term loan facility 264,147 265,000 — — 265,000 December 31, 2017 Carrying Value Estimated Fair Value Total Level 1 Level 2 Level 3 Interest rate swaps included in prepaid expenses and other assets $ — $ — $ — $ — $ — Interest rate swaps included in accounts payable and accrued expenses 436 436 — 436 — Mortgage notes payable 717,164 707,300 — — 707,300 Senior unsecured notes - Exchangeable 244,739 275,723 — 275,723 — Senior unsecured notes - Series A, B, C, D, E and F 463,156 460,352 — — 460,352 Unsecured term loan facility 263,662 265,000 — — 265,000

Rental Income (Tables)

Rental Income (Tables)	12 Months Ended
	Dec. 31, 2018
Leases [Abstract]
Schedule of Future Minimum Payments Receivable for Operating Leases	As of December 31, 2018 , we were entitled to the following future contractual minimum lease payments on non-cancellable operating leases to be received which expire on various dates through 2038 (amounts in thousands): 2019 $ 485,441 2020 460,127 2021 423,365 2022 391,395 2023 362,738 Thereafter 1,536,461 $ 3,659,527

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Lease Payments	Future minimum lease payments to be paid over the terms of the leases are as follows (amounts in thousands): 2019 $ 1,518 2020 1,518 2021 1,518 2022 1,518 2023 1,518 Thereafter 68,298 Total $ 75,888
Summary of Percent of Total Rental Revenue	For the years ended December 31, 2018 , 2017 and 2016, the six properties listed below accounted for the indicated percentage of total rental revenues. No other property accounted for more than 5.0% of total rental revenues. Year Ended December 31, 2018 2017 2016 Empire State Building 31.9 % 32.0 % 32.6 % One Grand Central Place 12.8 % 13.1 % 12.5 % 111 West 33rd Street 9.3 % 8.6 % 6.8 % 1400 Broadway 7.1 % 7.4 % 7.8 % First Stamford Place 5.9 % 5.4 % 6.4 % 250 West 57th Street 5.2 % 5.2 % 5.3 %
Schedule of Contributions to Multiemployer Plans	Contributions we made to the multi-employer plans for the years ended December 31, 2018, 2017 and 2016 are included in the table below (amounts in thousands): For the Year Ended December 31, Benefit Plan 2018 2017 2016 Pension Plans (pension and annuity)* $ 3,327 $ 3,035 $ 3,155 Health Plans** 9,373 8,551 8,280 Other*** 814 856 542 Total plan contributions $ 13,514 $ 12,442 $ 11,977 * Pension plans include $1.0 million, $0.9 million and $0.8 million for the years ended 2018, 2017 and 2016, respectively, to multiemployer plans not discussed above. ** Health plans include $1.6 million, $1.6 million and $1.6 million for the years ended 2018, 2017 and 2016, respectively, to multiemployer plans not discussed above. *** Other consists of union costs which were not itemized between pension and health plans. Other includes $0.2 million, $0.2 million and $0.2 million for the years ended 2018, 2017 and 2016, respectively, in connection with other multiemployer plans not discussed above.

Equity (Tables)

Equity (Tables)	12 Months Ended
	Dec. 31, 2018
Stockholders' Equity Note Disclosure, Disclosure of Compensation Related Costs, Share-based Payments and Earnings Per Share [Abstract]
Schedule of Change in Net Income Attributable to Common Shareholders	The following is net income attributable to common stockholders and the issuance of our class A shares in exchange for the conversion of OP Units into common stock (amounts in thousands): Year ended December 31, 2018 2017 2016 Net income attributable to common stockholders $ 65,603 $ 62,647 $ 51,456 Increase in additional paid-in capital for the conversion of OP Units into common stock 70,452 23,529 24,044 Change from net income attributable to common stockholders and transfers from noncontrolling interests $ 136,055 $ 86,176 $ 75,500
Dividends Declared	The following table summarizes the dividends paid on our Class A common stock and Class B common stock for the years ended December 31, 2018, 2017 and 2016: Record Date Payment Date Amount per Share December 17, 2018 December 31, 2018 $0.105 September 14, 2018 September 28, 2018 $0.105 June 15, 2018 June 29, 2018 $0.105 March 15, 2018 March 30, 2018 $0.105 December 15, 2017 December 29, 2017 $0.105 September 15, 2017 September 29, 2017 $0.105 June 15, 2017 June 30, 2017 $0.105 March 15, 2017 March 31, 2017 $0.105 December 15, 2016 December 29, 2016 $0.105 September 19, 2016 September 30, 2016 $0.105 June 15, 2016 June 30, 2016 $0.105 March 16, 2016 March 31, 2016 $0.085
Summary of Restricted Stock and Long-Term Incentive Plan Activity	The following is a summary of restricted stock and LTIP unit activity for the year ended December 31, 2018 : Restricted Stock LTIP Units Weighted Average Grant Fair Value Unvested balance at December 31, 2017 90,791 3,588,609 $ 11.20 Vested (30,693 ) (495,303 ) 14.59 Granted 39,608 2,719,801 8.54 Forfeited or unearned (8,548 ) (110,286 ) 8.50 Unvested balance at December 31, 2018 91,158 5,702,821 $ 9.68
Schedule of Earnings Per Share, Basic and Diluted	Earnings per share for the years ended December 31, 2018 , 2017 and 2016 is computed as follows (amounts in thousands, except per share amounts): For the Year Ended December 31, 2018 2017 2016 Numerator - Basic: Net income $ 117,253 $ 118,253 $ 107,250 Private perpetual preferred unit distributions (936 ) (936 ) (936 ) Net income attributable to non-controlling interests (50,714 ) (54,670 ) (54,858 ) Earnings allocated to unvested shares (38 ) (36 ) (36 ) Net income attributable to common stockholders - basic $ 65,565 $ 62,611 $ 51,420 Numerator - Diluted: Net income $ 117,253 $ 118,253 $ 107,250 Private perpetual preferred unit distributions (936 ) (936 ) (936 ) Earnings allocated to unvested shares (38 ) (36 ) (36 ) Net income attributable to common stockholders - diluted $ 116,279 $ 117,281 $ 106,278 Denominator: Weighted average shares outstanding - basic 167,571 158,380 133,881 Operating partnership units 129,687 138,075 142,967 Effect of dilutive securities: Stock-based compensation plans 1 775 454 Exchangeable senior notes — 819 266 Weighted average shares outstanding - diluted 297,259 298,049 277,568 Earnings per share - basic $ 0.39 $ 0.40 $ 0.38 Earnings per share - diluted $ 0.39 $ 0.39 $ 0.38

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense	TRS Holdings and Observatory TRS are taxable entities and their consolidated provision for income taxes consisted of the following for the years ended December 31, 2018 , 2017 and 2016 (amounts in thousands): For the Year Ended December 31, 2018 2017 2016 Current: Federal $ (2,389 ) $ (3,923 ) $ (3,632 ) State and local (2,253 ) (2,304 ) (2,055 ) Total current (4,642 ) (6,227 ) (5,687 ) Deferred: Federal — (446 ) (291 ) State and local — — (168 ) Total deferred — (446 ) (459 ) Income tax expense $ (4,642 ) $ (6,673 ) $ (6,146 )
Schedule of Actual Tax Provision Differed From Federal Statutory Corporate Rate	The actual tax provision differed from that computed at the federal statutory corporate rate as follows (amounts in thousands): For the Year Ended December 31, 2018 2017 2016 Federal tax expense at statutory rate $ (2,844 ) $ (4,684 ) $ (4,629 ) State income taxes, net of federal benefit (1,798 ) (1,543 ) (1,517 ) Corporate income tax rate adjustment — (446 ) — Income tax expense $ (4,642 ) $ (6,673 ) $ (6,146 )
Schedule of Deferred Tax Assets	The income tax effects of temporary differences that give rise to deferred tax assets are presented below as of December 31, 2018 , 2017 and 2016 (amounts in thousands): 2018 2017 2016 Deferred tax assets: Deferred revenue on unredeemed observatory admission ticket sales $ 1,396 $ 1,395 $ 198

Segment Reporting (Tables)

Segment Reporting (Tables)	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	The following tables provide components of segment profit for each segment for the years ended December 31, 2018 , 2017 and 2016, as reviewed by management (amounts in thousands): 2018 Real Estate Observatory Intersegment Elimination Total Revenues: Rental revenue $ 493,231 $ — $ — $ 493,231 Intercompany rental revenue 79,954 — (79,954 ) — Tenant expense reimbursement 72,372 — — 72,372 Observatory revenue — 131,227 — 131,227 Lease termination fees 20,847 — — 20,847 Third-party management and other fees 1,440 — — 1,440 Other revenue and fees 12,394 — — 12,394 Total revenues 680,238 131,227 (79,954 ) 731,511 Operating expenses: Property operating expenses 167,379 — — 167,379 Intercompany rent expense — 79,954 (79,954 ) — Ground rent expense 9,326 — — 9,326 General and administrative expenses 52,674 — — 52,674 Observatory expenses — 32,767 — 32,767 Real estate taxes 110,000 — — 110,000 Depreciation and amortization 168,430 78 — 168,508 Total operating expenses 507,809 112,799 (79,954 ) 540,654 Total operating income 172,429 18,428 — 190,857 Other income (expense): Interest income 10,661 — — 10,661 Interest expense (79,623 ) — — (79,623 ) Income before income taxes 103,467 18,428 — 121,895 Income tax expense (1,114 ) (3,528 ) — (4,642 ) Net income $ 102,353 $ 14,900 $ — $ 117,253 Segment assets $ 3,930,330 $ 265,450 $ — $ 4,195,780 Expenditures for segment assets $ 201,685 $ 54,811 $ — $ 256,496 2017 Real Estate Observatory Intersegment Elimination Total Revenues: Rental revenue $ 483,944 $ — $ — $ 483,944 Intercompany rental revenue 77,646 — (77,646 ) — Tenant expense reimbursement 73,679 — — 73,679 Observatory revenue — 127,118 — 127,118 Lease termination fees 13,551 — — 13,551 Third-party management and other fees 1,400 — — 1,400 Other revenue and fees 9,834 — — 9,834 Total revenues 660,054 127,118 (77,646 ) 709,526 Operating expenses: Property operating expenses 163,531 — — 163,531 Intercompany rent expense — 77,646 (77,646 ) — Ground rent expense 9,326 — — 9,326 General and administrative expenses 50,315 — — 50,315 Observatory expenses — 30,275 — 30,275 Real estate taxes 102,466 — — 102,466 Depreciation and amortization 160,630 80 — 160,710 Total operating expenses 486,268 108,001 (77,646 ) 516,623 Total operating income (loss) 173,786 19,117 — 192,903 Other income (expense): Interest income 2,942 — — 2,942 Interest expense (68,473 ) — — (68,473 ) Loss on early extinguishment of debt (2,157 ) — — (2,157 ) Loss from derivative financial instrument (289 ) — — (289 ) Income before income taxes 105,809 19,117 — 124,926 Income tax expense (1,306 ) (5,367 ) — (6,673 ) Net income $ 104,503 $ 13,750 $ — $ 118,253 Segment assets $ 3,670,907 $ 260,440 $ — $ 3,931,347 Expenditures for segment assets $ 191,541 $ 36,621 $ — $ 228,162 2016 Real Estate Observatory Intersegment Elimination Total Revenues: Rental revenue $ 460,653 $ — $ — $ 460,653 Intercompany rental revenue 75,658 — (75,658 ) — Tenant expense reimbursement 73,459 — — 73,459 Observatory revenue — 124,814 — 124,814 Lease termination fees 7,676 — — 7,676 Third-party management and other fees 1,766 — — 1,766 Other revenue and fees 8,970 15 — 8,985 Total revenues 628,182 124,829 (75,658 ) 677,353 Operating expenses: Property operating expenses 153,850 — — 153,850 Intercompany rent expense — 75,658 (75,658 ) — Ground rent expense 9,326 — — 9,326 General and administrative expenses 49,078 — — 49,078 Observatory expenses — 29,833 — 29,833 Real estate taxes 96,061 — — 96,061 Acquisition expenses 98 — — 98 Depreciation and amortization 154,817 394 — 155,211 Total operating expenses 463,230 105,885 (75,658 ) 493,457 Total operating income (loss) 164,952 18,944 — 183,896 Other income (expense): Interest income 647 — — 647 Interest expense (70,595 ) — — (70,595 ) Loss on early extinguishment of debt (552 ) — — (552 ) Income (loss) before income taxes 94,452 18,944 — 113,396 Income tax expense (1,361 ) (4,785 ) — (6,146 ) Net income $ 93,091 $ 14,159 $ — $ 107,250 Segment assets $ 3,641,844 $ 249,109 $ — $ 3,890,953 Expenditures for segment assets $ 197,680 $ — $ — $ 197,680

Summary of Quarterly Financia_2

Summary of Quarterly Financial Information (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	The quarterly results of operations of our company for the years ended December 31, 2018 , 2017 and 2016 are as follows (amounts in thousands): March 31, 2018 June 30, 2018 September 30, 2018 December 31, 2018 Revenues $ 167,271 $ 178,529 $ 186,402 $ 199,309 Operating income $ 34,164 $ 49,665 $ 48,538 $ 58,490 Net income $ 18,058 $ 30,184 $ 29,230 $ 39,781 Net income attributable to common stockholders $ 9,768 $ 16,651 $ 16,342 $ 22,842 Net income per share attributable to common stockholders: Basic and diluted $ 0.06 $ 0.10 $ 0.10 $ 0.13 March 31, 2017 June 30, 2017 September 30, 2017 December 31, 2017 Revenues $ 164,333 $ 176,349 $ 186,547 $ 182,297 Operating income $ 36,045 $ 50,659 $ 56,008 $ 50,191 Net income $ 19,145 $ 31,359 $ 35,489 $ 32,260 Net income attributable to common stockholders $ 9,985 $ 16,584 $ 18,806 $ 17,272 Net income per share attributable to common stockholders: Basic and diluted $ 0.06 $ 0.10 $ 0.12 $ 0.11 March 31, 2016 June 30, 2016 September 30, 2016 December 31, 2016 Revenues $ 157,057 $ 165,785 $ 175,704 $ 178,807 Operating income $ 34,097 $ 44,162 $ 53,442 $ 52,195 Net income $ 16,705 $ 24,640 $ 32,897 $ 33,008 Net income attributable to common stockholders $ 7,428 $ 11,089 $ 15,973 $ 16,966 Net income per share attributable to common stockholders: Basic and diluted $ 0.06 $ 0.09 $ 0.12 $ 0.11

Description of Business and O_2

Description of Business and Organization - Narrative (Details)	12 Months Ended
	Dec. 31, 2018ft²entityparceloffice_and_property
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Area of real estate property (in sqft)	10,100,000
OP units owned by the Company, percent	57.70%
Number of entities to be treated as taxable REIT subsidiary | entity	2
Office
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Area of real estate property (in sqft)	9,400,000
Number of offices and properties (property) | office_and_property	14
Office | Manhattan
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Area of real estate property (in sqft)	7,600,000
Number of offices and properties (property) | office_and_property	9
Office | Fairfield County, Connecticut and Westchester County, New York
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Area of real estate property (in sqft)	1,800,000
Number of offices and properties (property) | office_and_property	5
Development Parcel
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Number of offices and properties (property) | parcel	3
Retail | Manhattan and Westport, Connecticut
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Area of real estate property (in sqft)	205,748
Retail | Manhattan
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Area of real estate property (in sqft)	513,606
Number of offices and properties (property) | office_and_property	4
Retail | Westport, Connecticut
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Number of offices and properties (property) | office_and_property	2
Other Property | Stamford, Connecticut
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Area of real estate property (in sqft)	380,000

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Narrative (Details)	12 Months Ended
	Dec. 31, 2018USD ($)segment	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Jan. 01, 2019USD ($)
Accounting Policies [Line Items]
Deferred revenue	$ 4,100,000	$ 4,100,000
Advertising and marketing expense	8,900,000	7,600,000	$ 9,400,000
Interest costs capitalized	$ 1,600,000	$ 500,000	$ 0
Number of reportable segments (segment) | segment	2
Remaining contractual payments under ground lease agreements	$ 75,888,000
Capitalized internal leasing costs	$ 4,600,000
Building and Building Improvements
Accounting Policies [Line Items]
Useful life	39 years
Corporate Equipment | Minimum
Accounting Policies [Line Items]
Useful life	3 years
Corporate Equipment | Maximum
Accounting Policies [Line Items]
Useful life	7 years
Subsequent Event | ASU 2016-02
Accounting Policies [Line Items]
Operating lease, right-of-use assets				$ 30,000,000
Operating lease, liabilities				$ 30,000,000

Deferred Costs, Acquired Leas_3

Deferred Costs, Acquired Lease Intangibles and Goodwill - Schedule of Deferred Costs, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred Costs [Line Items]
Leasing costs	$ 178,120	$ 164,751
Total deferred costs, gross amount	444,806	469,530
Less: accumulated amortization	(209,839)	(215,102)
Total deferred costs, net, excluding net deferred financing costs	234,967	254,428
Acquired in-place lease value and deferred leasing costs
Deferred Costs [Line Items]
Acquired finite-lived intangible assets, gross	214,550	237,364
Acquired above-market leases
Deferred Costs [Line Items]
Acquired finite-lived intangible assets, gross	$ 52,136	$ 67,415

Deferred Costs, Acquired Leas_4

Deferred Costs, Acquired Lease Intangibles and Goodwill - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2013
Deferred Costs [Line Items]
Amortization of deferred leasing and acquired deferred leasing costs	$ 26,300	$ 24,100	$ 24,200
Amortization of acquired above and below-market leases, net	6,120	5,721	8,795
Goodwill	491,479	491,479
Empire State Building observatory operations
Deferred Costs [Line Items]
Goodwill				$ 227,500
Empire State Building
Deferred Costs [Line Items]
Goodwill				250,800
501 Seventh Avenue
Deferred Costs [Line Items]
Goodwill				$ 13,200
Lease agreements
Deferred Costs [Line Items]
Amortization expense related to acquired lease intangibles	$ 12,100	17,100	$ 24,600
Ground lease
Deferred Costs [Line Items]
Weighted-average amortization period	24 years 6 months
In-place leases and deferred leasing costs
Deferred Costs [Line Items]
Weighted-average amortization period	4 years 6 months
Above-market leases
Deferred Costs [Line Items]
Weighted-average amortization period	3 years 9 months
Below-market Lease
Deferred Costs [Line Items]
Weighted-average amortization period	4 years
Unsecured revolving credit facility | Revolving Credit Facility
Deferred Costs [Line Items]
Net deferred financing costs	$ 6,300	$ 8,300

Deferred Costs, Acquired Leas_5

Deferred Costs, Acquired Lease Intangibles and Goodwill - Acquired Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Acquired below-market ground leases	$ 396,916	$ 396,916
Less: accumulated amortization	(36,518)	(28,687)
Acquired below-market ground leases, net	360,398	368,229
Acquired below-market leases	(118,462)	(132,026)
Less: accumulated amortization	66,012	65,979
Acquired below-market leases, net	$ (52,450)	$ (66,047)

Deferred Costs, Acquired Leas_6

Deferred Costs, Acquired Lease Intangibles and Goodwill - Future Amortization Expense and Rental Revenue (Details) $ in Thousands	Dec. 31, 2018USD ($)
Future Rental Revenue [Abstract]
2,019	$ 6,875
2,020	3,651
2,021	2,868
2,022	3,185
2,023	3,181
Thereafter	9,532
Future Rental Revenue	29,292
Ground lease
Future Amortization Expense [Abstract]
2,019	7,831
2,020	7,831
2,021	7,831
2,022	7,831
2,023	7,831
Thereafter	321,243
Future Amortization Expense	360,398
Lease agreements
Future Amortization Expense [Abstract]
2,019	15,829
2,020	12,967
2,021	11,250
2,022	10,433
2,023	9,756
Thereafter	31,690
Future Amortization Expense	$ 91,925

Debt - Schedule of Long term D

Debt - Schedule of Long term Debt (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Jan. 31, 2018	Dec. 31, 2017	Aug. 31, 2017	Aug. 31, 2014
Debt Instrument [Line Items]
Unsecured revolving credit facility	$ 0		$ 0
Deferred financing costs, net	(15,288,000)		(17,407,000)
Total	608,567,000		717,164,000
Fixed rate mortgage debt
Debt Instrument [Line Items]
Fixed rate debt	614,612,000		721,224,000
Total principal	1,929,612,000		1,701,224,000
Unamortized (discount) premiums, net of unamortized premiums (discount)	(1,647,000)		(3,370,000)
Deferred financing costs, net	(9,032,000)		(9,133,000)
Total	1,918,933,000		1,688,721,000
Fixed rate mortgage debt | Metro Center
Debt Instrument [Line Items]
Fixed rate debt	$ 91,838,000		93,948,000
Stated Rate	3.59%
Effective rate (in percentage)	3.68%
Fixed rate mortgage debt | 10 Union Square
Debt Instrument [Line Items]
Fixed rate debt	$ 50,000,000		50,000,000
Stated Rate	3.70%
Effective rate (in percentage)	3.97%
Fixed rate mortgage debt | 1542 Third Avenue
Debt Instrument [Line Items]
Fixed rate debt	$ 30,000,000		30,000,000
Stated Rate	4.29%
Effective rate (in percentage)	4.53%
Fixed rate mortgage debt | First Stamford Place
Debt Instrument [Line Items]
Fixed rate debt	$ 180,000,000		180,000,000
Stated Rate	4.28%
Effective rate (in percentage)	4.45%
Fixed rate mortgage debt | First Stamford Place - First Lien
Debt Instrument [Line Items]
Stated Rate	4.09%
Face amount	$ 164,000,000
Fixed rate mortgage debt | First Stamford Place - Second Lien
Debt Instrument [Line Items]
Stated Rate	6.25%
Face amount	$ 16,000,000
Fixed rate mortgage debt | 1010 Third Avenue and 77 West 55th Street
Debt Instrument [Line Items]
Fixed rate debt	$ 38,995,000		39,710,000
Stated Rate	4.01%
Effective rate (in percentage)	4.22%
Fixed rate mortgage debt | 10 Bank Street
Debt Instrument [Line Items]
Fixed rate debt	$ 33,779,000		34,602,000
Stated Rate	4.23%
Effective rate (in percentage)	4.35%
Fixed rate mortgage debt | 383 Main Avenue
Debt Instrument [Line Items]
Fixed rate debt	$ 30,000,000		30,000,000
Stated Rate	4.44%
Effective rate (in percentage)	4.55%
Fixed rate mortgage debt | 1333 Broadway
Debt Instrument [Line Items]
Fixed rate debt	$ 160,000,000	$ 66,600,000	66,602,000
Stated Rate	4.21%
Effective rate (in percentage)	4.29%
Face amount		$ 160,000,000
Fixed rate mortgage debt | (first lien mortgage loan)
Debt Instrument [Line Items]
Fixed rate debt	$ 0		66,632,000
Stated Rate	0.00%
Effective rate (in percentage)	0.00%
Fixed rate mortgage debt | (second lien mortgage loan)
Debt Instrument [Line Items]
Fixed rate debt	$ 0		9,172,000
Stated Rate	0.00%
Effective rate (in percentage)	0.00%
Fixed rate mortgage debt | (first lien mortgage loan)
Debt Instrument [Line Items]
Fixed rate debt	$ 0		74,045,000
Stated Rate	0.00%
Effective rate (in percentage)	0.00%
Fixed rate mortgage debt | (second lien mortgage loan)
Debt Instrument [Line Items]
Fixed rate debt	$ 0		9,369,000
Stated Rate	0.00%
Effective rate (in percentage)	0.00%
Fixed rate mortgage debt | 1350 Broadway
Debt Instrument [Line Items]
Fixed rate debt	$ 0		37,144,000
Stated Rate	0.00%
Effective rate (in percentage)	0.00%
Senior unsecured notes - exchangeable | Senior unsecured notes - exchangeable
Debt Instrument [Line Items]
Fixed rate debt	$ 250,000,000		250,000,000
Stated Rate	2.625%				2.625%
Effective rate (in percentage)	3.93%				3.80%
Face amount					$ 250,000,000
Senior unsecured notes - Series A, B, C, D, E and F | Series A
Debt Instrument [Line Items]
Total	$ 100,000,000		100,000,000
Stated Rate	3.93%
Effective rate (in percentage)	3.96%
Senior unsecured notes - Series A, B, C, D, E and F | Series B
Debt Instrument [Line Items]
Total	$ 125,000,000		125,000,000
Stated Rate	4.09%
Effective rate (in percentage)	4.12%
Senior unsecured notes - Series A, B, C, D, E and F | Series C
Debt Instrument [Line Items]
Total	$ 125,000,000		125,000,000
Stated Rate	4.18%
Effective rate (in percentage)	4.21%
Senior unsecured notes - Series A, B, C, D, E and F | Series D
Debt Instrument [Line Items]
Total	$ 115,000,000		$ 115,000,000
Stated Rate	4.08%		4.08%
Effective rate (in percentage)	4.11%
Face amount			$ 115,000,000
Senior unsecured notes - Series A, B, C, D, E and F | Series E
Debt Instrument [Line Items]
Total	$ 160,000,000		$ 0
Stated Rate	4.26%		4.26%
Effective rate (in percentage)	4.27%
Face amount			$ 160,000,000
Senior unsecured notes - Series A, B, C, D, E and F | Series F
Debt Instrument [Line Items]
Total	$ 175,000,000		$ 0
Stated Rate	4.44%		4.44%
Effective rate (in percentage)	4.45%
Face amount			$ 175,000,000
Revolving Credit Facility | Unsecured revolving credit facility
Debt Instrument [Line Items]
Unsecured revolving credit facility	$ 0		0
Effective rate (in percentage)	3.60%
Revolving Credit Facility | Unsecured revolving credit facility | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	1.10%
Revolving Credit Facility | Unsecured term loan facility
Debt Instrument [Line Items]
Unsecured revolving credit facility	$ 265,000,000		$ 265,000,000	$ 265,000,000
Effective rate (in percentage)	2.1485%
Pay rate	3.35%
Revolving Credit Facility | Unsecured term loan facility | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	1.20%

Debt - Mortgage Debt (Details)

Debt - Mortgage Debt (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jan. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Repayments of mortgage loan		$ 266,613,000	$ 346,615,000	$ 32,305,000
Fixed rate mortgage debt
Debt Instrument [Line Items]
Fixed rate debt		614,612,000	721,224,000
Fixed rate mortgage debt | 1333 Broadway
Debt Instrument [Line Items]
Fixed rate debt	$ 66,600,000	$ 160,000,000	$ 66,602,000
Face amount	160,000,000
Fixed rate mortgage debt | 1400 Broadway
Debt Instrument [Line Items]
Repayments of mortgage loan	$ 75,800,000

Debt - Schedule of Maturities

Debt - Schedule of Maturities of Long-term Debt (Details) - Fixed rate mortgage debt - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Amortization [Abstract]
2019 Amortization	$ 3,790
2020 Amortization	3,938
2021 Amortization	4,090
2022 Amortization	5,628
2023 Amortization	7,876
Thereafter	33,868
Total Amortization	59,190
Maturities of Long-term Debt [Abstract]
2019 Maturities	250,000
2020 Maturities	0
2021 Maturities	0
2022 Maturities	265,000
2023 Maturities	0
Thereafter	1,355,422
Total Maturities	1,870,422
Total [Abstract]
2,019	253,790
2,020	3,938
2,021	4,090
2,022	270,628
2,023	7,876
Thereafter	1,389,290
Total	$ 1,929,612	$ 1,701,224

Debt - Deferred Financing Cost

Debt - Deferred Financing Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Financing costs	$ 25,315	$ 24,446
Less: accumulated amortization	(10,027)	(7,039)
Total deferred financing costs, net	15,288	17,407
Amortization of financing costs	4,100	4,700	$ 5,000
Revolving Credit Facility | Unsecured revolving credit facility
Debt Instrument [Line Items]
Net deferred financing costs	$ 6,300	$ 8,300

Debt - Unsecured Revolving Cre

Debt - Unsecured Revolving Credit and Term Loan Facility (Details)	1 Months Ended	12 Months Ended
	Aug. 31, 2017USD ($)option	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Debt Instrument [Line Items]
Loss on early extinguishment of debt		$ 0	$ 2,157,000	$ 552,000
Unsecured revolving credit facility		0	0
Revolving Credit Facility | Unsecured revolving credit facility
Debt Instrument [Line Items]
Loss on early extinguishment of debt			2,200,000
Current borrowing capacity	$ 1,100,000,000
Unsecured revolving credit facility		0	0
Option to extend maturity, number | option	2
Extension period (in months)	6 months
Maximum leverage ratio (in percentage)	60.00%
Maximum consolidated secured indebtedness to asset value (in percentage)	40.00%
Minimum tangible net worth	$ 1,200,000,000
Tangible net worth, minimum percent of net equity proceeds received (in percentage)	75.00%
Minimum adjusted EBITDA to consolidated fixed charges	1.50
Minimum net operating income to unsecured debt	1.75
Maximum ratio of unsecured debt to unencumbered asset value (in percentage)	60.00%
Revolving Credit Facility | Term Loan
Debt Instrument [Line Items]
Current borrowing capacity	$ 265,000,000
Unsecured revolving credit facility	265,000,000	$ 265,000,000	$ 265,000,000
Revolving Credit Facility | Unsecured Revolving Credit Facility And Term Loan
Debt Instrument [Line Items]
Maximum borrowing capacity	1,365,000,000
Credit facility higher borrowing capacity option	$ 1,750,000,000
Minimum | Revolving Credit Facility | Unsecured revolving credit facility
Debt Instrument [Line Items]
Extension fee percent of outstanding commitments under revolving credit facility (in percentage)	0.0625%
Maximum | Revolving Credit Facility | Unsecured revolving credit facility
Debt Instrument [Line Items]
Extension fee percent of outstanding commitments under revolving credit facility (in percentage)	0.075%

Debt - Senior Unsecured Notes

Debt - Senior Unsecured Notes Exchangeable (Details)	1 Months Ended	12 Months Ended
	Aug. 31, 2014USD ($)d$ / shares	Dec. 31, 2018USD ($)$ / shares	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Debt Instrument [Line Items]
Senior unsecured notes, net		$ 1,046,219,000	$ 707,895,000
Interest expense		79,623,000	68,473,000	$ 70,595,000
Amortization expense of deferred financing costs		$ 4,100,000	4,700,000	5,000,000
Senior unsecured notes - exchangeable | Senior unsecured notes - exchangeable
Debt Instrument [Line Items]
Face amount	$ 250,000,000
Stated interest rate	2.625%	2.625%
Conversion price (USD per share) | $ / shares	$ 19.45	$ 19.23
Debt, conversion ratio	0.0514059	0.0520116
Percentage of principal redeemed	100.00%
Effective rate (in percentage)	3.80%	3.93%
Senior unsecured notes, net	$ 236,600,000
Embedded conversion option		$ 13,400,000	13,400,000
Remaining discount amortization period (in years)	5 years
Unamortized discount		1,600,000	4,300,000
Underwriting expense	$ 3,100,000
Deferred finance costs	$ 2,900,000
Embedded conversion feature, reduction		200,000	200,000
Interest on note		9,900,000	9,900,000	9,900,000
Interest expense		6,600,000	6,600,000	6,600,000
Accretion of debt discount		2,700,000	2,700,000	2,700,000
Amortization expense of deferred financing costs		$ 600,000	$ 600,000	$ 600,000
Covenant scenario one | Senior unsecured notes - exchangeable | Senior unsecured notes - exchangeable
Debt Instrument [Line Items]
Threshold percentage of stock price trigger (in percentage)	130.00%
Threshold trading days | d	20
Threshold consecutive trading days | d	30
Covenant scenario two | Senior unsecured notes - exchangeable | Senior unsecured notes - exchangeable
Debt Instrument [Line Items]
Threshold percentage of stock price trigger (in percentage)	98.00%
Threshold consecutive trading days | d	5
Threshold consecutive business days	5 days

Debt - Senior Unsecured Note_2

Debt - Senior Unsecured Notes (Details) - Senior Notes - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Series D, Series E, and Series F Senior Unsecured Notes
Debt Instrument [Line Items]
Face amount		$ 450,000,000
Series D
Debt Instrument [Line Items]
Face amount		$ 115,000,000
Stated interest rate	4.08%	4.08%
Series E
Debt Instrument [Line Items]
Face amount		$ 160,000,000
Stated interest rate	4.26%	4.26%
Series F
Debt Instrument [Line Items]
Face amount		$ 175,000,000
Stated interest rate	4.44%	4.44%

Accounts Payable and Accrued _3

Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Payables and Accruals [Abstract]
Accrued capital expenditures	$ 85,242	$ 71,769
Accounts payable and accrued expenses	34,585	32,509
Interest rate swap agreements liability	5,243	436
Accrued interest payable	4,990	5,687
Due to affiliated companies	616	448
Total accounts payable and accrued expenses	$ 130,676	$ 110,849

Financial Instruments and Fai_3

Financial Instruments and Fair Values - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Interest rate swap agreements liability	$ 5,243	$ 436
Unrealized loss on valuation of interest rate swap agreements			$ 3,054
Loss from derivative financial instruments	0	289	0
Interest rate swaps
Derivative [Line Items]
Interest rate swap agreements liability	5,300
Designated as Hedging Instrument | Cash Flow Hedging
Derivative [Line Items]
Unrealized loss on valuation of interest rate swap agreements	900	10,500
Loss expected to be reclassified within twelve months	900
Loss from derivative financial instruments		300
Designated as Hedging Instrument | Cash Flow Hedging | Interest rate swaps
Derivative [Line Items]
Notional amount	515,000	265,000
Unrealized loss on valuation of interest rate swap agreements			$ 3,054
Prepaid expenses and other assets | Designated as Hedging Instrument | Cash Flow Hedging | Interest rate swaps
Derivative [Line Items]
Interest rate swap agreements asset	2,500
Accounts payable and accrued expenses | Designated as Hedging Instrument | Cash Flow Hedging | Interest rate swaps
Derivative [Line Items]
Interest rate swap agreements liability	$ 5,200	$ 400

Financial Instruments and Fai_4

Financial Instruments and Fair Values - Terms of Agreements and Fair Value (Details) - Cash Flow Hedging - Designated as Hedging Instrument - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Asset	$ 2,536,000	$ 0
Liability	(5,243,000)	(436,000)
Interest Rate Swap, One Month LIBOR, 2.1485% | LIBOR
Derivatives, Fair Value [Line Items]
Notional Amount	$ 265,000,000
Pay Rate	2.1485%
Asset	$ 2,536,000	0
Liability	0	(436,000)
Interest Rate Swap, Three Month LIBOR, 2.9580%, Swap Number 1 | LIBOR
Derivatives, Fair Value [Line Items]
Notional Amount	$ 125,000,000
Pay Rate	2.958%
Asset	$ 0	0
Liability	(2,623,000)	0
Interest Rate Swap, Three Month LIBOR, 2.9580%, Swap Number 2 | LIBOR
Derivatives, Fair Value [Line Items]
Notional Amount	$ 125,000,000
Pay Rate	2.958%
Asset	$ 0	0
Liability	$ (2,620,000)	$ 0

Financial Instruments and Fai_5

Financial Instruments and Fair Values - Gain and Loss of Cash Flow Hedges (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in other comprehensive income (loss)	$ (2,721)	$ (11,658)
Amount of gain (loss) recognized in other comprehensive income (loss)			$ (3,054)
Amount of gain (loss) reclassified from accumulated other comprehensive income (loss) into interest expense	(1,845)	(1,142)
Amount of gain (loss) reclassified from accumulated other comprehensive income (loss) into interest expense			0
Interest expense	(79,623)	(68,473)	(70,595)
Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in other comprehensive income (loss)	(2,721)
Amount of gain (loss) reclassified from accumulated other comprehensive income (loss) into interest expense	(1,845)
Cash Flow Hedging | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in other comprehensive income (loss)	(900)	(10,500)
Cash Flow Hedging | Designated as Hedging Instrument | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in other comprehensive income (loss)		(11,658)
Amount of gain (loss) recognized in other comprehensive income (loss)			(3,054)
Amount of gain (loss) reclassified from accumulated other comprehensive income (loss) into interest expense		(1,142)
Amount of gain (loss) reclassified from accumulated other comprehensive income (loss) into interest expense			0
Accumulated other comprehensive income (loss) | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Interest expense	$ (1,845)	$ (1,142)	$ 0

Financial Instruments and Fai_6

Financial Instruments and Fair Values - Schedule of the aggregate carrying value of debt and estimates of fair value (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swaps included in accounts payable and accrued expenses	$ 5,243	$ 436
Carrying Value | Revolving Credit Facility | Term Loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	264,147	263,662
Carrying Value | Fixed rate mortgage debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	608,567	717,164
Carrying Value | Senior unsecured notes - Exchangeable | Senior unsecured notes - Exchangeable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	247,930	244,739
Carrying Value | Senior unsecured notes - Series A, B, C, D, E and F
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	798,289	463,156
Estimated Fair Value | Revolving Credit Facility | Term Loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	265,000	265,000
Estimated Fair Value | Fixed rate mortgage debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	597,424	707,300
Estimated Fair Value | Senior unsecured notes - Exchangeable | Senior unsecured notes - Exchangeable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	250,625	275,723
Estimated Fair Value | Senior unsecured notes - Series A, B, C, D, E and F
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	795,662	460,352
Estimated Fair Value | Level 1 | Revolving Credit Facility | Term Loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Estimated Fair Value | Level 1 | Fixed rate mortgage debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Estimated Fair Value | Level 1 | Senior unsecured notes - Exchangeable | Senior unsecured notes - Exchangeable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Estimated Fair Value | Level 1 | Senior unsecured notes - Series A, B, C, D, E and F
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Estimated Fair Value | Level 2 | Revolving Credit Facility | Term Loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Estimated Fair Value | Level 2 | Fixed rate mortgage debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Estimated Fair Value | Level 2 | Senior unsecured notes - Exchangeable | Senior unsecured notes - Exchangeable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	250,625	275,723
Estimated Fair Value | Level 2 | Senior unsecured notes - Series A, B, C, D, E and F
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Estimated Fair Value | Level 3 | Revolving Credit Facility | Term Loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	265,000	265,000
Estimated Fair Value | Level 3 | Fixed rate mortgage debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	597,424	707,300
Estimated Fair Value | Level 3 | Senior unsecured notes - Exchangeable | Senior unsecured notes - Exchangeable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Estimated Fair Value | Level 3 | Senior unsecured notes - Series A, B, C, D, E and F
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	795,662	460,352
Interest rate swaps
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swaps included in accounts payable and accrued expenses	5,300
Interest rate swaps | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swaps included in prepaid expenses and other assets	2,536	0
Interest rate swaps included in accounts payable and accrued expenses	5,243	436
Interest rate swaps | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swaps included in prepaid expenses and other assets	2,536	0
Interest rate swaps included in accounts payable and accrued expenses	5,243	436
Interest rate swaps | Estimated Fair Value | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swaps included in prepaid expenses and other assets	0	0
Interest rate swaps included in accounts payable and accrued expenses	0	0
Interest rate swaps | Estimated Fair Value | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swaps included in prepaid expenses and other assets	2,536	0
Interest rate swaps included in accounts payable and accrued expenses	5,243	436
Interest rate swaps | Estimated Fair Value | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swaps included in prepaid expenses and other assets	0	0
Interest rate swaps included in accounts payable and accrued expenses	$ 0	$ 0

Rental Income - Schedule of Fu

Rental Income - Schedule of Future Minimum Payments Receivable for Operating Leases (Details) $ in Thousands	Dec. 31, 2018USD ($)
Operating Leases, Future Minimum Payments Receivable [Abstract]
2,019	$ 485,441
2,020	460,127
2,021	423,365
2,022	391,395
2,023	362,738
Thereafter	1,536,461
Total Future Minimum Payments Receivable for Operating Leases	$ 3,659,527

Commitments and Contingencies

Commitments and Contingencies - Litigation (Details)	Oct. 14, 2014participant
Predecessor | New York State Supreme Court, New York County
Loss Contingencies [Line Items]
Number of plaintiffs opting out of settlement (participant)	12

Commitments and Contingencies_2

Commitments and Contingencies - Ground Lease Commitments (Details) $ in Thousands	Dec. 31, 2018USD ($)property
Commitments and Contingencies Disclosure [Abstract]
Number of properties subject to ground leases (property) | property	3
2,019	$ 1,518
2,020	1,518
2,021	1,518
2,022	1,518
2,023	1,518
Thereafter	68,298
Total	$ 75,888

Commitments and Contingencies_3

Commitments and Contingencies - Unfunded Capital Expenditures (Details) $ in Millions	Dec. 31, 2018USD ($)
Commitments and Contingencies Disclosure [Abstract]
Unfunded capital expenditures	$ 88.4

Commitments and Contingencies_4

Commitments and Contingencies - Major Customers and Other Concentrations (Details) - Customer concentration risk - Rental revenue	12 Months Ended
	Dec. 31, 2018office_and_propertytenant	Dec. 31, 2017office_and_propertytenant	Dec. 31, 2016office_and_propertytenant
Concentration Risk [Line Items]
Number of tenants | tenant	5	5	5
Number of properties (property) | office_and_property	6	6	6
Empire State Building
Concentration Risk [Line Items]
Concentration risk percentage	31.90%	32.00%	32.60%
One Grand Central Place
Concentration Risk [Line Items]
Concentration risk percentage	12.80%	13.10%	12.50%
111 West 33rd Street
Concentration Risk [Line Items]
Concentration risk percentage	9.30%	8.60%	6.80%
1400 Broadway
Concentration Risk [Line Items]
Concentration risk percentage	7.10%	7.40%	7.80%
First Stamford Place
Concentration Risk [Line Items]
Concentration risk percentage	5.90%	5.40%	6.40%
250 West 57th Street
Concentration Risk [Line Items]
Concentration risk percentage	5.20%	5.20%	5.30%
Customer 1
Concentration Risk [Line Items]
Concentration risk percentage	6.00%	6.30%	6.40%
Customer 2
Concentration Risk [Line Items]
Concentration risk percentage	3.10%	3.20%	3.30%
Customer 3
Concentration Risk [Line Items]
Concentration risk percentage	2.90%	2.90%	2.90%
Customer 4
Concentration Risk [Line Items]
Concentration risk percentage	2.00%	2.10%	2.30%
Customer 5
Concentration Risk [Line Items]
Concentration risk percentage	2.00%	2.00%	2.00%

Commitments and Contingencies_5

Commitments and Contingencies - Multiemployer Pension and Defined Contribution Plans Narrative (Details) - Building Service 32BJ - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2016
Pension Plans
Multiemployer Plans [Line Items]
Plan contributions	$ 272.3	$ 257.8	$ 249.5
Health Plans
Multiemployer Plans [Line Items]
Plan contributions	$ 1,400	$ 1,300	$ 1,200

Commitments and Contingencies_6

Commitments and Contingencies - Schedule of Contributions made to Multiemployer Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Multiemployer Plans [Line Items]
Contributions	$ 13,514	$ 12,442	$ 11,977
Pension Plans
Multiemployer Plans [Line Items]
Contributions	3,327	3,035	3,155
Pension Plans | Multiemployer Plan, Individually Insignificant Multiemployer Plans
Multiemployer Plans [Line Items]
Contributions	1,000	900	800
Health Plans
Multiemployer Plans [Line Items]
Contributions	9,373	8,551	8,280
Health Plans | Multiemployer Plan, Individually Insignificant Multiemployer Plans
Multiemployer Plans [Line Items]
Contributions	1,600	1,600	1,600
Other
Multiemployer Plans [Line Items]
Contributions	814	856	542
Other | Multiemployer Plan, Individually Insignificant Multiemployer Plans
Multiemployer Plans [Line Items]
Contributions	$ 200	$ 200	$ 200

Equity (Details)

Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 31, 2018	Sep. 28, 2018	Jun. 29, 2018	Mar. 30, 2018	Dec. 29, 2017	Sep. 29, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 29, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Mar. 31, 2018
Class of Stock [Line Items]
Gross proceeds from sale of shares													$ 4,700	$ 4,749	$ 0	$ 611,206
Percentage of dividends on common stock received until performance criteria met for LTIP units	10.00%													10.00%
Percentage of dividends on common stock received after performance criteria met for LTIP units	90.00%													90.00%
Percentage of dividends on common stock received in periods after performance criteria met for LTIP units	100.00%													100.00%
Shares and Units [Abstract]
Net income attributable to common stockholders														$ 65,603	62,647	51,456
Increase in additional paid-in capital for the conversion of OP Units into common stock														0	0	0
Change from net income attributable to common stockholders and transfers from noncontrolling interests														$ 136,055	$ 86,176	$ 75,500
OP units outstanding (shares)	303,300,000													303,300,000
OP units owned by the Company (shares)	174,900,000													174,900,000
OP units owned by the Company, percent														57.70%
OP units not owned by the Company (shares)	128,400,000													128,400,000
OP units not owned by the Company, percent														42.30%
Private perpetual preferred units, liquidation preference per share (in dollars per share)	$ 16.62													$ 16.62	$ 16.62
Dividends (USD per share)														$ 0.42	$ 0.42	$ 0.4
Dividends and Distributions [Abstract]
Partial dividend paid, per common share (USD per share)	0.105	$ 0.105	$ 0.105	$ 0.105	$ 0.105	$ 0.105	$ 0.105	$ 0.105	$ 0.105	$ 0.105	$ 0.105	$ 0.085
Payments of ordinary dividends, common stock														$ 70,900	$ 66,800	$ 55,800
Distributions paid to OP unitholders														54,700	59,200	58,200
Private perpetual preferred unit distributions														$ 936	$ 936	$ 936
Dividends paid, percent taxable as ordinary dividends														83.80%	100.00%	100.00%
Dividends paid, percent taxable as return of capital														16.20%
Private Perpetual Preferred Units
Shares and Units [Abstract]
Private perpetual preferred units (shares)														1,560,360
Private perpetual preferred units, liquidation preference per share (in dollars per share)	$ 16.62													$ 16.62
Dividends (USD per share)														$ 0.60
Common Stock | Class A Common Stock
Class of Stock [Line Items]
Issuance of common shares (in shares)													284,015	284,000		29,610,854
Common shares issued (USD per share)													$ 16.72			$ 21
Shares and Units [Abstract]
Increase in additional paid-in capital for the conversion of OP Units into common stock														$ 132	$ 57	$ 62
Additional Paid-In Capital
Shares and Units [Abstract]
Increase in additional paid-in capital for the conversion of OP Units into common stock														$ 70,452	$ 23,529	$ 24,044
Q REIT Holding LLC
Class of Stock [Line Items]
Interest held by Q REIT Holding LLC																9.90%	9.90%
Q REIT Holding LLC | Common Stock | Class A Common Stock
Class of Stock [Line Items]
Interest held by Q REIT Holding LLC																19.40%
Gross proceeds from sale of shares																$ 621,800

Equity - Incentive and Share-b

Equity - Incentive and Share-based Compensation (Details) $ / shares in Units, $ in Millions	1 Months Ended					12 Months Ended
	May 31, 2018USD ($)shares	Mar. 31, 2018USD ($)vesting_installmentshares	Feb. 28, 2018USD ($)vesting_installmentshares	May 31, 2017USD ($)shares	Mar. 31, 2017USD ($)vesting_installmentshares	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares	Dec. 31, 2016USD ($)$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility rate look-back period						6 years
Period of service, upon completion of which, grantee's LTIP unit and restricted stock awards will immediately vest						10 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Unvested beginning balance, per share (USD per share) | $ / shares						$ 11.20
Vested, weighted average grant price, per share (USD per share) | $ / shares						14.59
Granted, weighted average grant price, per share (USD per share) | $ / shares						8.54
Forfeited or unearned, weighted average grant price, per share (USD per share) | $ / shares						8.50
Unvested ending balance, per share (USD per share) | $ / shares						$ 9.68	$ 11.20
Age of grantee at which LTIP unit and restricted stock awards immediately vest						60 years
Long-Term Incentive Plan Unit and Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of share-based awards granted in period | $						$ 23.6	$ 19.4	$ 18.4
Expected term						2 years 9 months 12 days
Risk-free interest rate						2.50%
Expected price volatility						20.00%
Share-based compensation arrangement by share-based payment award, fair value assumptions, expected dividend rate						2.30%	2.05%	2.10%
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Granted, weighted average grant price, per share (USD per share) | $ / shares						$ 8.54	$ 13.77	$ 9.60
Long-Term Incentive Plan Unit and Restricted Stock | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term							2 years 9 months 12 days	2 years 10 months
Risk-free interest rate							1.55%	0.84%
Expected price volatility							20.00%	24.00%
Time Based Long-Tern Incentive Plan Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of share-based awards granted in period | $					$ 1.6
Restricted Stock and LTIP Unit Activity [Roll Forward]
Granted (in shares)					47,993
Performance Based Long-Term Incentive Plan Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of share-based awards granted in period | $					$ 1
Restricted Stock and LTIP Unit Activity [Roll Forward]
Granted (in shares)					95,156
Time Restricted Shares
Restricted Stock and LTIP Unit Activity [Roll Forward]
Granted (in shares)					34,407
Restricted Stock
Restricted Stock and LTIP Unit Activity [Roll Forward]
Unvested beginning balance (in shares)						90,791
Vested (in shares)						(30,693)
Granted (in shares)						39,608
Forfeited or unearned (in shares)						(8,548)
Unvested ending balance (in shares)						91,158	90,791
Long-Term Incentive Plan Unit
Restricted Stock and LTIP Unit Activity [Roll Forward]
Unvested beginning balance (in shares)						3,588,609
Vested (in shares)						(495,303)
Granted (in shares)						2,719,801
Forfeited or unearned (in shares)						(110,286)
Unvested ending balance (in shares)						5,702,821	3,588,609
Long-Term Incentive Plan Units and Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Fair value vested in period | $						$ 7.7	$ 7.6	$ 5.1
2013 Plan Units, Granted in March 2018 | Time Based Long-Tern Incentive Plan Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of share-based awards granted in period | $		$ 1.7
Award vesting period		4 years
Number of vesting installments | vesting_installment		3
Restricted Stock and LTIP Unit Activity [Roll Forward]
Granted (in shares)		67,449
2013 Plan Units, Granted in March 2018 | Performance Based Long-Term Incentive Plan Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of share-based awards granted in period | $		$ 1.1
Award vesting period		3 years
Number of vesting installments | vesting_installment		2
Restricted Stock and LTIP Unit Activity [Roll Forward]
Granted (in shares)		223,950
2013 Plan Units, Granted in March 2018 | Time Restricted Shares
Restricted Stock and LTIP Unit Activity [Roll Forward]
Granted (in shares)		39,608
Awards that Meet Age and Service Requirements for Vesting
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Noncash share-based compensation expense recognized | $						1.8	1	0.7
Unrecognized compensation expense | $						$ 1
Unrecognized compensation expense, period for recognition (in years)						1 year 13 months 12 days
Awards that Do Not Meet Age and Service Requirements for Vesting
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Noncash share-based compensation expense recognized | $						$ 17	$ 13.1	$ 9
Unrecognized compensation expense | $						$ 27.4
Unrecognized compensation expense, period for recognition (in years)						2 years 2 months
Director | Time Based Long-Tern Incentive Plan Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of share-based awards granted in period | $	$ 1
Award vesting period	3 years
Restricted Stock and LTIP Unit Activity [Roll Forward]
Granted (in shares)	65,000
Director | 2013 Plan Units Granted In May 2017 | Time Based Long-Tern Incentive Plan Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of share-based awards granted in period | $				$ 1
Award vesting period				3 years
Restricted Stock and LTIP Unit Activity [Roll Forward]
Granted (in shares)				50,408
Executive Officer | 2013 Plan Units, Granted in March 2018 | Time Based Long-Tern Incentive Plan Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of share-based awards granted in period | $		$ 6.1
Restricted Stock and LTIP Unit Activity [Roll Forward]
Granted (in shares)		386,876
Executive Officer | 2013 Plan Units, Granted in March 2018 | Performance Based Long-Term Incentive Plan Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of share-based awards granted in period | $		$ 9.6
Restricted Stock and LTIP Unit Activity [Roll Forward]
Granted (in shares)		1,737,917
Executive Officer | 2013 Plan Units, Granted in March 2017 | Time Based Long-Tern Incentive Plan Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of share-based awards granted in period | $					$ 6.1
Award vesting period					4 years
Number of vesting installments | vesting_installment					3
Restricted Stock and LTIP Unit Activity [Roll Forward]
Granted (in shares)					313,275
Executive Officer | 2013 Plan Units, Granted in March 2017 | Performance Based Long-Term Incentive Plan Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of share-based awards granted in period | $					$ 9.6
Award vesting period					3 years
Number of vesting installments | vesting_installment					2
Restricted Stock and LTIP Unit Activity [Roll Forward]
Granted (in shares)					865,742
Executive Officer | 2013 Plan Units, Granted in February 2018 | Time Based Long-Tern Incentive Plan Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of share-based awards granted in period | $			$ 4
Award vesting period							3 years
Award vesting percentage of award face amount							125.00%
Restricted Stock and LTIP Unit Activity [Roll Forward]
Granted (in shares)			238,609
Executive Officer | Vest immediately | Time Based Long-Tern Incentive Plan Unit
Restricted Stock and LTIP Unit Activity [Roll Forward]
Granted (in shares)			25,158
Executive Officer | Vest over three years | Time Based Long-Tern Incentive Plan Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			3 years
Restricted Stock and LTIP Unit Activity [Roll Forward]
Granted (in shares)			213,451
Executive Officer | Vest in two equal annual installments | Time Based Long-Tern Incentive Plan Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of vesting installments | vesting_installment			2
2013 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized under the plan (shares)						12,200,000
Number of shares that remain available for future issuance (shares)						4,300,000

Equity - Earnings Per Share (D

Equity - Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Numerator:
Net income	$ 39,781	$ 29,230	$ 30,184	$ 18,058	$ 32,260	$ 35,489	$ 31,359	$ 19,145	$ 33,008	$ 32,897	$ 24,640	$ 16,705	$ 117,253	$ 118,253	$ 107,250
Private perpetual preferred unit distributions													(936)	(936)	(936)
Net income attributable to non-controlling interests													(50,714)	(54,670)	(54,858)
Earnings allocated to unvested shares													(38)	(36)	(36)
Net income attributable to common stockholders - basic													65,565	62,611	51,420
Earnings allocated to unvested shares													(38)	(36)	(36)
Net income attributable to common stockholders - diluted													$ 116,279	$ 117,281	$ 106,278
Denominator:
Weighted average shares outstanding - basic (shares)													167,571,000	158,380,000	133,881,000
Operating partnership units (shares)													129,687,000	138,075,000	142,967,000
Effect of dilutive securities, stock-based compensation plans (shares)													1,000	775,000	454,000
Effect of dilutive securities, exchangeable senior notes (shares)													0	819,000	266,000
Weighted average shares outstanding - dilutive (in shares)													297,259,000	298,049,000	277,568,000
Basic (USD per share)													$ 0.39	$ 0.40	$ 0.38
Diluted (USD per share)													$ 0.39	$ 0.39	$ 0.38
Antidilutive securities (shares)													485,865	834,267	800,746

Related Party Transactions - Q

Related Party Transactions - QIA (Details) - Q REIT Holding LLC $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Noncontrolling Interest [Line Items]
Minimum interest required to be held by affiliate of QIA in order to purchase new equity securities	5.00%
Threshold of equity securities issuance where top up rights are exercisable	$ 1
Right to first offer to co-invest, period (in months)	30 months
Term for JV (in years)	5 years
Extended term (in months)	30 months
Threshold to indemnify	10.00%

Related Party Transactions - T

Related Party Transactions - Tax Protection Agreement (Details) - Affiliated Entity $ in Millions	Oct. 07, 2013USD ($)	Dec. 31, 2013property
Related Party Transaction [Line Items]
Number of properties protected (property) | property		4
Aggregate number of operating partnership units and common stock threshold during tax protection period	50.00%
Bottom dollar guarantee of aggregate indebtedness during tax protection period | $	$ 160

Related Party Transactions - R

Related Party Transactions - Registration Rights (Details) - Registration rights agreement	12 Months Ended
	Dec. 31, 2018USD ($)$ / underwritten_offeringunderwritten_offering
Related Party Transaction [Line Items]
Number of underwritten offerings, maximum, during 12-month period following shelf effective date | underwritten_offering	2
Primary shares cutback value, minimum | $	$ 25,000,000
Payments for fees and registration per underwritten offering, maximum (in dollars per offering) | $ / underwritten_offering	25,000
Certain persons receiving common stock or operating partnership units in formation transactions
Related Party Transaction [Line Items]
Registrable shares market value, minimum | $	$ 150,000,000
Number of underwritten offerings, maximum | underwritten_offering	4

Related Party Transactions - E

Related Party Transactions - Excluded Properties and Businesses (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)office_and_propertyinterestproperty	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Retail | Manhattan
Related Party Transaction [Line Items]
Number of properties (property) | office_and_property	4
Office
Related Party Transaction [Line Items]
Number of properties (property) | office_and_property	14
Office | Manhattan
Related Party Transaction [Line Items]
Number of properties (property) | office_and_property	9
Malkin Group | Mezzanine and Senior Equity Funds
Related Party Transaction [Line Items]
Number of interests owned (interest) | interest	2
Malkin Group | Residential Property Manager
Related Party Transaction [Line Items]
Number of properties (property) | interest	5
Number of interests owned (interest) | interest	5
Malkin Group | Multi-family Property | Greenwich, Connecticut
Related Party Transaction [Line Items]
Number of properties (property)	8
Malkin Group | Retail | Greenwich, Connecticut
Related Party Transaction [Line Items]
Number of properties (property)	5
Malkin Group | Retail | Manhattan
Related Party Transaction [Line Items]
Number of properties (property)	2
Malkin Group | Former Post Office | Greenwich, Connecticut
Related Party Transaction [Line Items]
Number of properties (property)	1
Malkin Group | Office | Manhattan
Related Party Transaction [Line Items]
Number of properties (property)	1
Supervisory fee revenue | Third party management and other fees | Affiliated Entity
Related Party Transaction [Line Items]
Revenue from related parties | $	$ 1.1	$ 1.1	$ 1.4
Property management fee revenue | Third party management and other fees | Affiliated Entity
Related Party Transaction [Line Items]
Revenue from related parties | $	$ 0.3	$ 0.3	$ 0.4

Related Party Transactions - O

Related Party Transactions - Other (Details)	1 Months Ended	12 Months Ended
	Aug. 31, 2016ft²property	Dec. 31, 2018USD ($)ft²directorproperty	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Related Party Transaction [Line Items]
Area of real estate property (in sqft) | ft²		10,100,000
Number of directors (in directors) | director		1
Affiliated Entity | Leased space rental
Related Party Transaction [Line Items]
Revenue from related parties				$ 200,000
Area of real estate property (in sqft) | ft²		3,074
Number of properties (property) | property		1
Affiliated Entity | Annualized rent revenue
Related Party Transaction [Line Items]
Revenue from related parties		$ 4,500,000	$ 5,800,000
Undivided Interest
Related Party Transaction [Line Items]
Area of real estate property (in sqft) | ft²	5,351	647
Chairman emeritus | Leased space rental
Related Party Transaction [Line Items]
Number of properties (property) | property	1
Lease cancellation, period of notice	90 days
Percentage of lease space occupied by Chairman emeritus and employee	15.00%
Revenue from related parties, net of payment for pro rata share of leased space		$ 300,000	$ 400,000	100,000
Chairman emeritus | Purchase of miscellaneous furniture and artwork
Related Party Transaction [Line Items]
Revenue from related parties				$ 23,300

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Current federal tax	$ (2,389)	$ (3,923)	$ (3,632)
Current state tax	(2,253)	(2,304)	(2,055)
Total current	(4,642)	(6,227)	(5,687)
Deferred federal tax	0	(446)	(291)
Deferred state tax	0	0	(168)
Total deferred	0	(446)	(459)
Income tax expense	$ (4,642)	(6,673)	$ (6,146)
Increase in income tax expense		400
Decrease in deferred tax asset		$ 400
Effective income tax rate, percent	34.00%	48.50%	44.80%
Federal tax expense at statutory rate	$ (2,844)	$ (4,684)	$ (4,629)
State income taxes, net of federal benefit	(1,798)	(1,543)	(1,517)
Corporate income tax rate adjustment	$ 0	$ (446)	$ 0

Income Taxes - Schedule of Def

Income Taxes - Schedule of Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Deferred revenue on unredeemed observatory admission ticket sales	$ 1,396	$ 1,395	$ 198

Segment Reporting - Reportable

Segment Reporting - Reportable Segments (Details)	12 Months Ended
	Dec. 31, 2018segment
Segment Reporting [Abstract]
Number of reportable segments (segment)	2

Segment Reporting - Segment Re

Segment Reporting - Segment Revenue and Profit or Loss Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Revenue and Profit or Loss from Segments to Consolidated [Line Items]
Rental revenue													$ 493,231	$ 483,944	$ 460,653
Intercompany rental revenue													0	0	0
Tenant expense reimbursement													72,372	73,679	73,459
Observatory revenue													131,227	127,118	124,814
Lease termination fees													20,847	13,551	7,676
Third-party management and other fees													1,440	1,400	1,766
Other revenue and fees													12,394	9,834	8,985
Total revenues	$ 199,309	$ 186,402	$ 178,529	$ 167,271	$ 182,297	$ 186,547	$ 176,349	$ 164,333	$ 178,807	$ 175,704	$ 165,785	$ 157,057	731,511	709,526	677,353
Property operating expenses													167,379	163,531	153,850
Intercompany rent expense													0	0	0
Ground rent expenses													9,326	9,326	9,326
General and administrative expenses													52,674	50,315	49,078
Observatory expenses													32,767	30,275	29,833
Real estate taxes													110,000	102,466	96,061
Acquisition expenses													0	0	98
Depreciation and amortization													168,508	160,710	155,211
Total operating expenses													540,654	516,623	493,457
Total operating income (loss)	58,490	48,538	49,665	34,164	50,191	56,008	50,659	36,045	52,195	53,442	44,162	34,097	190,857	192,903	183,896
Interest income													10,661	2,942	647
Interest expense													(79,623)	(68,473)	(70,595)
Loss on early extinguishment of debt													0	(2,157)	(552)
Loss from derivative financial instruments													0	(289)	0
Income before income taxes													121,895	124,926	113,396
Income tax expense													(4,642)	(6,673)	(6,146)
Net income	39,781	$ 29,230	$ 30,184	$ 18,058	32,260	$ 35,489	$ 31,359	$ 19,145	33,008	$ 32,897	$ 24,640	$ 16,705	117,253	118,253	107,250
Segment assets	4,195,780				3,931,347				3,890,953				4,195,780	3,931,347	3,890,953
Expenditures for segment assets													256,496	228,162	197,680
Intersegment Elimination
Reconciliation of Revenue and Profit or Loss from Segments to Consolidated [Line Items]
Rental revenue													0	0	0
Intercompany rental revenue													(79,954)	(77,646)	(75,658)
Tenant expense reimbursement													0	0	0
Observatory revenue													0	0	0
Lease termination fees													0	0	0
Third-party management and other fees													0	0	0
Other revenue and fees													0	0	0
Total revenues													(79,954)	(77,646)	(75,658)
Property operating expenses													0	0	0
Intercompany rent expense													(79,954)	(77,646)	(75,658)
Ground rent expenses													0	0	0
General and administrative expenses													0	0	0
Observatory expenses													0	0	0
Real estate taxes													0	0	0
Acquisition expenses															0
Depreciation and amortization													0	0	0
Total operating expenses													(79,954)	(77,646)	(75,658)
Total operating income (loss)													0	0	0
Interest income													0	0	0
Interest expense													0	0	0
Loss on early extinguishment of debt														0	0
Loss from derivative financial instruments														0
Income before income taxes													0	0	0
Income tax expense													0	0	0
Net income													0	0	0
Segment assets	0				0				0				0	0	0
Expenditures for segment assets													0	0	0
Real Estate | Operating Segments
Reconciliation of Revenue and Profit or Loss from Segments to Consolidated [Line Items]
Rental revenue													493,231	483,944	460,653
Intercompany rental revenue													79,954	77,646	75,658
Tenant expense reimbursement													72,372	73,679	73,459
Observatory revenue													0	0	0
Lease termination fees													20,847	13,551	7,676
Third-party management and other fees													1,440	1,400	1,766
Other revenue and fees													12,394	9,834	8,970
Total revenues													680,238	660,054	628,182
Property operating expenses													167,379	163,531	153,850
Intercompany rent expense													0	0	0
Ground rent expenses													9,326	9,326	9,326
General and administrative expenses													52,674	50,315	49,078
Observatory expenses													0	0	0
Real estate taxes													110,000	102,466	96,061
Acquisition expenses															98
Depreciation and amortization													168,430	160,630	154,817
Total operating expenses													507,809	486,268	463,230
Total operating income (loss)													172,429	173,786	164,952
Interest income													10,661	2,942	647
Interest expense													(79,623)	(68,473)	(70,595)
Loss on early extinguishment of debt														(2,157)	(552)
Loss from derivative financial instruments														(289)
Income before income taxes													103,467	105,809	94,452
Income tax expense													(1,114)	(1,306)	(1,361)
Net income													102,353	104,503	93,091
Segment assets	3,930,330				3,670,907				3,641,844				3,930,330	3,670,907	3,641,844
Expenditures for segment assets													201,685	191,541	197,680
Observatory | Operating Segments
Reconciliation of Revenue and Profit or Loss from Segments to Consolidated [Line Items]
Rental revenue													0	0	0
Intercompany rental revenue													0	0	0
Tenant expense reimbursement													0	0	0
Observatory revenue													131,227	127,118	124,814
Lease termination fees													0	0	0
Third-party management and other fees													0	0	0
Other revenue and fees													0	0	15
Total revenues													131,227	127,118	124,829
Property operating expenses													0	0	0
Intercompany rent expense													79,954	77,646	75,658
Ground rent expenses													0	0	0
General and administrative expenses													0	0	0
Observatory expenses													32,767	30,275	29,833
Real estate taxes													0	0	0
Acquisition expenses															0
Depreciation and amortization													78	80	394
Total operating expenses													112,799	108,001	105,885
Total operating income (loss)													18,428	19,117	18,944
Interest income													0	0	0
Interest expense													0	0	0
Loss on early extinguishment of debt														0	0
Loss from derivative financial instruments														0
Income before income taxes													18,428	19,117	18,944
Income tax expense													(3,528)	(5,367)	(4,785)
Net income													14,900	13,750	14,159
Segment assets	$ 265,450				$ 260,440				$ 249,109				265,450	260,440	249,109
Expenditures for segment assets													$ 54,811	$ 36,621	$ 0

Summary of Quarterly Financia_3

Summary of Quarterly Financial Information (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 199,309	$ 186,402	$ 178,529	$ 167,271	$ 182,297	$ 186,547	$ 176,349	$ 164,333	$ 178,807	$ 175,704	$ 165,785	$ 157,057	$ 731,511	$ 709,526	$ 677,353
Operating income	58,490	48,538	49,665	34,164	50,191	56,008	50,659	36,045	52,195	53,442	44,162	34,097	190,857	192,903	183,896
Net income	39,781	29,230	30,184	18,058	32,260	35,489	31,359	19,145	33,008	32,897	24,640	16,705	$ 117,253	$ 118,253	$ 107,250
Net income attributable to common stockholders	$ 22,842	$ 16,342	$ 16,651	$ 9,768	$ 17,272	$ 18,806	$ 16,584	$ 9,985	$ 16,966	$ 15,973	$ 11,089	$ 7,428
Basic and diluted net income per share attributable to common stockholders (USD per share)	$ 0.13	$ 0.10	$ 0.10	$ 0.06	$ 0.11	$ 0.12	$ 0.10	$ 0.06	$ 0.11	$ 0.12	$ 0.09	$ 0.06

Schedule II - Valuation and Q_2

Schedule II - Valuation and Qualifying Accounts (Details) - SEC Schedule, 12-09, Allowance, Credit Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance At Beginning of Year	$ 1,607	$ 3,723	$ 3,037
Additions Charged Against Operations	(811)	(1,650)	908
Uncollectible Accounts Written-Off	(289)	(466)	(222)
Balance at End of Year	$ 507	$ 1,607	$ 3,723

Schedule III - Real Estate an_2

Schedule III - Real Estate and Accumulated Depreciation - Schedule of Real Estate and Accumulated Depreciation (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	$ 608,567
Initial Cost to the Company
Land	199,287
Building & Improvements	918,018
Cost Capitalized Subsequent to Acquisition
Improvements	1,767,181
Gross Amount at which Carried
Land	209,183
Buildings & Improvements	2,675,303
Total	2,884,486	$ 2,667,655	$ 2,458,629	$ 2,276,330
Accumulated Depreciation	(747,304)	$ (656,900)	$ (556,546)	$ (465,584)
111 West 33rd Street, New York, NY | office/ retail
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to the Company
Land	13,630
Building & Improvements	244,461
Cost Capitalized Subsequent to Acquisition
Improvements	106,780
Gross Amount at which Carried
Land	13,630
Buildings & Improvements	351,241
Total	364,871
Accumulated Depreciation	(41,629)
1400 Broadway | office/ retail
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to the Company
Land	0
Building & Improvements	96,338
Cost Capitalized Subsequent to Acquisition
Improvements	40,261
Gross Amount at which Carried
Land	0
Buildings & Improvements	136,599
Total	136,599
Accumulated Depreciation	(31,601)
1333 Broadway, New York, NY | office/ retail
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	158,484
Initial Cost to the Company
Land	91,435
Building & Improvements	120,190
Cost Capitalized Subsequent to Acquisition
Improvements	7,491
Gross Amount at which Carried
Land	91,435
Buildings & Improvements	127,681
Total	219,116
Accumulated Depreciation	(22,331)
1350 Broadway, New York, NY | office/ retail
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to the Company
Land	0
Building & Improvements	102,518
Cost Capitalized Subsequent to Acquisition
Improvements	27,161
Gross Amount at which Carried
Land	0
Buildings & Improvements	129,679
Total	129,679
Accumulated Depreciation	(25,312)
250 West 57th Street, New York, NY | office/ retail
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to the Company
Land	2,117
Building & Improvements	5,041
Cost Capitalized Subsequent to Acquisition
Improvements	141,581
Gross Amount at which Carried
Land	2,117
Buildings & Improvements	146,622
Total	148,739
Accumulated Depreciation	(36,058)
501 Seventh Avenue, New York, NY | office/ retail
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to the Company
Land	1,100
Building & Improvements	2,600
Cost Capitalized Subsequent to Acquisition
Improvements	94,778
Gross Amount at which Carried
Land	1,100
Buildings & Improvements	97,378
Total	98,478
Accumulated Depreciation	(43,164)
1359 Broadway, New York, NY | office/ retail
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to the Company
Land	1,233
Building & Improvements	1,809
Cost Capitalized Subsequent to Acquisition
Improvements	57,938
Gross Amount at which Carried
Land	1,233
Buildings & Improvements	59,747
Total	60,980
Accumulated Depreciation	(26,549)
350 Fifth Avenue (Empire State Building), New York, NY | office/ retail
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to the Company
Land	21,551
Building & Improvements	38,934
Cost Capitalized Subsequent to Acquisition
Improvements	895,989
Gross Amount at which Carried
Land	21,551
Buildings & Improvements	934,923
Total	956,474
Accumulated Depreciation	(211,068)
One Grand Central Place, New York, NY | office/ retail
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to the Company
Land	7,240
Building & Improvements	17,490
Cost Capitalized Subsequent to Acquisition
Improvements	241,218
Gross Amount at which Carried
Land	7,222
Buildings & Improvements	258,726
Total	265,948
Accumulated Depreciation	(109,502)
First Stamford Place, Stamford, CT | office
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	178,616
Initial Cost to the Company
Land	22,952
Building & Improvements	122,739
Cost Capitalized Subsequent to Acquisition
Improvements	63,292
Gross Amount at which Carried
Land	24,862
Buildings & Improvements	184,121
Total	208,983
Accumulated Depreciation	(78,570)
One Station Place, Stamford, CT (Metro Center) | office
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	91,592
Initial Cost to the Company
Land	5,313
Building & Improvements	28,602
Cost Capitalized Subsequent to Acquisition
Improvements	15,301
Gross Amount at which Carried
Land	5,313
Buildings & Improvements	43,903
Total	49,216
Accumulated Depreciation	(30,763)
383 Main Avenue, Norwalk, CT | office
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	29,614
Initial Cost to the Company
Land	2,262
Building & Improvements	12,820
Cost Capitalized Subsequent to Acquisition
Improvements	22,253
Gross Amount at which Carried
Land	2,262
Buildings & Improvements	35,073
Total	37,335
Accumulated Depreciation	(12,876)
500 Mamaroneck Avenue, Harrison, NY | office
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to the Company
Land	4,571
Building & Improvements	25,915
Cost Capitalized Subsequent to Acquisition
Improvements	22,198
Gross Amount at which Carried
Land	4,571
Buildings & Improvements	48,113
Total	52,684
Accumulated Depreciation	(23,147)
10 Bank Street, White Plains, NY | office
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	33,316
Initial Cost to the Company
Land	5,612
Building & Improvements	31,803
Cost Capitalized Subsequent to Acquisition
Improvements	18,412
Gross Amount at which Carried
Land	5,612
Buildings & Improvements	50,215
Total	55,827
Accumulated Depreciation	(21,134)
10 Union Square, New York, NY | retail
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	49,116
Initial Cost to the Company
Land	5,003
Building & Improvements	12,866
Cost Capitalized Subsequent to Acquisition
Improvements	1,966
Gross Amount at which Carried
Land	5,003
Buildings & Improvements	14,832
Total	19,835
Accumulated Depreciation	(7,801)
1542 Third Avenue, New York, NY | retail
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	29,459
Initial Cost to the Company
Land	2,239
Building & Improvements	15,266
Cost Capitalized Subsequent to Acquisition
Improvements	425
Gross Amount at which Carried
Land	2,239
Buildings & Improvements	15,691
Total	17,930
Accumulated Depreciation	(7,774)
1010 Third Avenue, New York, NY and 77 West 55th Street, New York, NY | retail
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	38,370
Initial Cost to the Company
Land	4,462
Building & Improvements	15,817
Cost Capitalized Subsequent to Acquisition
Improvements	783
Gross Amount at which Carried
Land	4,462
Buildings & Improvements	16,600
Total	21,062
Accumulated Depreciation	(8,590)
69-97 Main Street, Westport, CT | retail
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to the Company
Land	2,782
Building & Improvements	15,766
Cost Capitalized Subsequent to Acquisition
Improvements	1,046
Gross Amount at which Carried
Land	2,782
Buildings & Improvements	16,812
Total	19,594
Accumulated Depreciation	(7,113)
103-107 Main Street, Westport, CT | retail
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to the Company
Land	1,243
Building & Improvements	7,043
Cost Capitalized Subsequent to Acquisition
Improvements	321
Gross Amount at which Carried
Land	1,260
Buildings & Improvements	7,347
Total	8,607
Accumulated Depreciation	(2,322)
Property for development at the Transportation Hub in Stamford, CT | land
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial Cost to the Company
Land	4,542
Building & Improvements	0
Cost Capitalized Subsequent to Acquisition
Improvements	7,987
Gross Amount at which Carried
Land	12,529
Buildings & Improvements	0
Total	12,529
Accumulated Depreciation	$ 0

Schedule III - Real Estate an_3

Schedule III - Real Estate and Accumulated Depreciation - Reconciliation of Investment Properties (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]
Balance, beginning of year	$ 2,667,655	$ 2,458,629	$ 2,276,330
Acquisition of new properties	0	0	0
Improvements	256,496	228,162	197,680
Disposals	(39,665)	(19,136)	(15,381)
Balance, end of year	2,884,486	$ 2,667,655	$ 2,458,629
Aggregate cost of investment properties for federal income tax purpose	$ 2,500,000

Schedule III - Real Estate an_4

Schedule III - Real Estate and Accumulated Depreciation - Reconciliation of Accumulated Depreciation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation [Roll Forward]
Balance, beginning of year	$ 656,900	$ 556,546	$ 465,584
Depreciation expense	130,069	119,490	106,343
Disposals	(39,665)	(19,136)	(15,381)
Balance, end of year	$ 747,304	$ 656,900	$ 556,546

Schedule III - Real Estate an_5

Schedule III - Real Estate and Accumulated Depreciation - Schedule of Estimated Useful Lives of Investment Properties (Details)	12 Months Ended
	Dec. 31, 2018
Building
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Estimated original useful lives	39 years
Building Improvements
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Estimated original useful lives	39 years

Uncategorized Items - esrt-2018

Label	Element	Value
Derivative Financial Instruments Included in Prepaid Expenses and Other Assets	esrt_DerivativeFinancialInstrumentsIncludedinPrepaidExpensesandOtherAssets	$ 614,000
Derivative Financial Instruments Included in Prepaid Expenses and Other Assets	esrt_DerivativeFinancialInstrumentsIncludedinPrepaidExpensesandOtherAssets	0
Derivative Financial Instruments Included in Prepaid Expenses and Other Assets	esrt_DerivativeFinancialInstrumentsIncludedinPrepaidExpensesandOtherAssets	2,536,000
Derivative Financial Instruments Included in Accounts Payable and Accrued Expense	esrt_DerivativeFinancialInstrumentsIncludedinAccountsPayableandAccruedExpense	5,591,000
Derivative Financial Instruments Included in Accounts Payable and Accrued Expense	esrt_DerivativeFinancialInstrumentsIncludedinAccountsPayableandAccruedExpense	436,000
Derivative Financial Instruments Included in Accounts Payable and Accrued Expense	esrt_DerivativeFinancialInstrumentsIncludedinAccountsPayableandAccruedExpense	$ 5,243,000