Empire State Realty OP (FISK) 10-Q 6 Nov 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 30, 2018
Entity Registrant Name	Empire State Realty OP, L.P.
Entity Central Index Key	1,553,079
Document Type	10-Q
Current Fiscal Year End Date	--12-31
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Series ES operating partnership units
Entity Common Stock, Shares Outstanding		30,472,278
Series 60 operating partnership units
Entity Common Stock, Shares Outstanding		8,167,490
Series 250 operating partnership units
Entity Common Stock, Shares Outstanding		4,124,727

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Commercial real estate properties, at cost:
Land	$ 201,196	$ 201,196
Development costs	7,987	7,986
Building and improvements	2,616,772	2,458,473
Commercial real estate properties, at cost	2,825,955	2,667,655
Less: accumulated depreciation	(718,959)	(656,900)
Commercial real estate properties, net	2,106,996	2,010,755
Cash and cash equivalents	229,745	464,344
Restricted cash	54,356	65,853
Short-term investments	400,000	0
Tenant and other receivables, net of allowance of $1,616 and $1,422 in 2018 and 2017, respectively	31,342	28,329
Deferred rent receivables, net of allowance of $22 and $185 in 2018 and 2017, respectively	195,455	178,629
Prepaid expenses and other assets	50,663	61,028
Deferred costs, net	244,441	262,701
Acquired below-market ground leases, net	362,355	368,229
Goodwill	491,479	491,479
Total assets	4,166,832	3,931,347
Liabilities:
Mortgage notes payable, net	609,299	717,164
Senior unsecured notes, net	1,045,362	707,895
Unsecured term loan facility, net	264,023	263,662
Unsecured revolving credit facility	0	0
Accounts payable and accrued expenses	128,340	110,849
Acquired below-market leases, net	55,662	66,047
Deferred revenue and other liabilities	32,175	40,907
Tenants’ security deposits	42,520	47,086
Total liabilities	2,177,381	1,953,610
Commitments and contingencies
Capital:
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 capital	1,989,451	1,977,737
Total liabilities and capital	4,166,832	3,931,347
Series PR operating partnership units
Capital:
ESRT partner's capital (3,033,336 and 3,004,095 general partner operating partnership units and 166,187,567 and 158,472,949 limited partner operating partnership units outstanding in 2018 and 2017, respectively)	1,201,546	1,168,282
Limited partner operating partnership units	759,168	778,279
Series ES operating partnership units
Capital:
Limited partner operating partnership units	15,275	17,132
Series 60 operating partnership units
Capital:
Limited partner operating partnership units	3,541	3,992
Series 250 operating partnership units
Capital:
Limited partner operating partnership units	$ 1,917	$ 2,048

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Assets
Tenant and other receivables allowance	$ 1,616	$ 1,422
Deferred rent receivables allowance	$ 22	$ 185
Capital
Private perpetual preferred units, liquidation preference (in USD per share)	$ 16.62	$ 16.62
Private perpetual preferred units, issued (in shares)	1,560,360	1,560,360
Private perpetual preferred units, outstanding (in shares)	1,560,360	1,560,360
General partner operating partnership units, outstanding (in shares)	169,220,903
Limited partner operating partnership units, outstanding (in shares)	134,112,696
Series PR operating partnership units
Capital
Limited partner operating partnership units, outstanding (in shares)	90,799,640	91,759,741
Series ES operating partnership units
Capital
Limited partner operating partnership units, outstanding (in shares)	30,910,322	33,774,678
Series 60 operating partnership units
Capital
Limited partner operating partnership units, outstanding (in shares)	8,244,466	8,987,931
Series 250 operating partnership units
Capital
Limited partner operating partnership units, outstanding (in shares)	4,158,268	4,410,093
ESRT | Series PR operating partnership units
Capital
General partner operating partnership units, outstanding (in shares)	3,033,336	3,004,095
Limited partner operating partnership units, outstanding (in shares)	166,187,567	158,472,949

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income (unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues:
Rental revenue	$ 123,621	$ 122,391	$ 369,970	$ 360,348
Tenant expense reimbursement	18,627	20,346	52,626	53,889
Observatory revenue	40,241	39,306	96,691	94,212
Lease termination fees	1,185	1,165	2,164	10,354
Third-party management and other fees	312	345	1,151	1,088
Other revenue and fees	2,416	2,993	9,600	7,338
Revenues	$ 186,402	$ 186,546	$ 532,202	$ 527,229
Earnings per unit attributable to common unitholders:
Basic (in USD per unit)	$ 0.10	$ 0.12	$ 0.26	$ 0.29
Diluted (in USD per unit)	$ 0.10	$ 0.12	$ 0.26	$ 0.28
Total weighted average units:
Basic (in units)	297,478	296,389	297,180	296,389
Diluted (in units)	297,478	297,871	297,181	298,089
Other income (expense):
Interest income	$ 3,485	$ 774	$ 7,209	$ 2,169
Interest expense	(20,658)	(16,890)	(58,774)	(52,109)
Loss on early extinguishment of debt	0	(2,157)	0	(2,157)
Loss from derivative financial instruments	0	0	0	(289)
Income before income taxes	31,365	37,734	80,802	90,326
Income tax expense	(2,135)	(2,245)	(3,330)	(4,333)
Net income	29,230	35,489	77,472	85,993
Private perpetual preferred unit distributions	(234)	(234)	(702)	(702)
Net income attributable to common unitholders	28,996	35,255	76,770	85,291
Operating expenses:
Property operating expenses	42,772	41,270	126,375	122,009
Ground rent expenses	2,331	2,331	6,994	6,994
General and administrative expenses	13,148	12,899	39,001	36,566
Observatory expenses	8,854	8,648	23,868	23,079
Real estate taxes	28,284	26,901	81,771	76,001
Depreciation and amortization	42,475	38,490	121,826	119,868
Total operating expenses	137,864	130,539	399,835	384,517
Total operating income	$ 48,538	$ 56,007	$ 132,367	$ 142,712
Dividends per unit (in USD per unit)	$ 0.105	$ 0.105	$ 0.315	$ 0.315

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income (Loss) (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 29,230	$ 35,489	$ 77,472	$ 85,993
Other comprehensive income (loss):
Unrealized gain (loss) on valuation of interest rate swap agreements	3,884	(1,638)	9,827	(14,654)
Less: amount reclassified into interest expense	427	359	1,562	402
Other comprehensive income (loss)	4,311	(1,279)	11,389	(14,252)
Comprehensive income (loss)	$ 33,541	$ 34,210	$ 88,861	$ 71,741

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Capital (unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning balance		$ 1,977,737
Issuance of OP units, net of costs		4,749
Equity compensation		14,064
Distributions		(95,960)
Net income	$ 29,230	77,472
Other comprehensive income (loss)	4,311	11,389
Ending balance	$ 1,989,451	$ 1,989,451
General Partner | Series PR operating partnership units
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning balance (in units)		161,477
Beginning balance		$ 1,168,282
Issuance of OP units, net of costs (in units)		284
Issuance of OP units, net of costs		$ 4,749
Conversion of operating partnership units to ESRT Partner's Capital (in units)		7,436
Conversion of operating partnership units to ESRT Partner's Capital		$ 31,660
Equity compensation (in units)		24
Equity compensation		$ 269
Distributions		(52,519)
Net income		42,761
Other comprehensive income (loss)		$ 6,344
Ending balance (in units)	169,221	169,221
Ending balance	$ 1,201,546	$ 1,201,546
Limited Partner | Series PR operating partnership units
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning balance (in units)		91,760
Beginning balance		$ 778,279
Conversion of operating partnership units to ESRT Partner's Capital (in units)		(3,576)
Conversion of operating partnership units to ESRT Partner's Capital		$ (29,835)
Equity compensation (in units)		2,616
Equity compensation		$ 13,795
Distributions		(28,725)
Net income		22,340
Other comprehensive income (loss)		$ 3,314
Ending balance (in units)	90,800	90,800
Ending balance	$ 759,168	$ 759,168
Limited Partner | Series ES operating partnership units
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning balance (in units)		33,774
Beginning balance		$ 17,132
Conversion of operating partnership units to ESRT Partner's Capital (in units)		(2,864)
Conversion of operating partnership units to ESRT Partner's Capital		$ (1,394)
Distributions		(9,984)
Net income		8,291
Other comprehensive income (loss)		$ 1,230
Ending balance (in units)	30,910	30,910
Ending balance	$ 15,275	$ 15,275
Limited Partner | Series 60 operating partnership units
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning balance (in units)		8,988
Beginning balance		$ 3,992
Conversion of operating partnership units to ESRT Partner's Capital (in units)		(744)
Conversion of operating partnership units to ESRT Partner's Capital		$ (318)
Distributions		(2,689)
Net income		2,226
Other comprehensive income (loss)		$ 330
Ending balance (in units)	8,244	8,244
Ending balance	$ 3,541	$ 3,541
Limited Partner | Series 250 operating partnership units
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning balance (in units)		4,410
Beginning balance		$ 2,048
Conversion of operating partnership units to ESRT Partner's Capital (in units)		(252)
Conversion of operating partnership units to ESRT Partner's Capital		$ (113)
Distributions		(1,341)
Net income		1,152
Other comprehensive income (loss)		$ 171
Ending balance (in units)	4,158	4,158
Ending balance	$ 1,917	$ 1,917
Private Perpetual Preferred Units
Increase (Decrease) in Partners' Capital [Roll Forward]
Beginning balance (in units)		1,560
Beginning balance		$ 8,004
Distributions		(702)
Net income		$ 702
Ending balance (in units)	1,560	1,560
Ending balance	$ 8,004	$ 8,004

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash Flows From Operating Activities
Net income	$ 77,472	$ 85,993
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	121,826	119,868
Amortization of non-cash items within interest expense	5,142	919
Amortization of acquired above- and below-market leases, net	(4,387)	(4,154)
Amortization of acquired below-market ground leases	5,873	5,873
Straight-lining of rental revenue	(16,662)	(20,590)
Equity based compensation	14,064	10,808
Settlement of derivative contracts	0	(6,335)
Unrealized loss from derivative financial instruments	0	2,157
Increase (decrease) in cash flows due to changes in operating assets and liabilities:
Security deposits	(4,566)	213
Tenant and other receivables	(3,176)	(12,119)
Deferred leasing costs	(18,578)	(21,660)
Prepaid expenses and other assets	20,308	13,672
Accounts payable and accrued expenses	(1,181)	(8,917)
Deferred revenue and other liabilities	(8,732)	9,108
Net cash provided by operating activities	187,403	174,836
Cash Flows From Investing Activities
Short-term investments	(400,000)	0
Development costs	(1)	(27)
Additions to building and improvements	(169,622)	(157,579)
Net cash used in investing activities	(569,623)	(157,606)
Cash Flows From Financing Activities
Proceeds from mortgage notes payable	160,000	315,000
Repayment of mortgage notes payable	(265,688)	(344,618)
Proceeds from unsecured senior notes	335,000	0
Proceeds from unsecured revolving credit facility and term loan	0	265,000
Repayments of unsecured revolving credit facility and term loan	0	(265,000)
Proceeds from the sale of common stock	4,749	0
Deferred financing costs	(1,977)	(12,186)
Distributions	(95,960)	(95,186)
Net cash provided by (used in) financing activities	136,124	(136,990)
Net decrease in cash and cash equivalents and restricted cash	(246,096)	(119,760)
Cash and cash equivalents and restricted cash—beginning of period	530,197	615,885
Cash and cash equivalents and restricted cash—end of period	284,101	496,125
Reconciliation of Cash and Cash Equivalents and Restricted Cash:
Cash and cash equivalents at beginning of period	464,344	554,371
Restricted cash at beginning of period	65,853	61,514
Cash and cash equivalents at end of period	229,745	432,105
Restricted cash at end of period	54,356	64,020
Supplemental disclosures of cash flow information:
Cash paid for interest	56,597	53,918
Cash paid for income taxes	3,690	5,004
Non-cash investing and financing activities:
Building and improvements included in accounts payable and accrued expenses	92,506	72,130
Derivative instruments at fair values included in prepaid expenses and other assets	9,944	0
Derivative instruments at fair values included in accounts payable and accrued expenses	0	13,378
Conversion of limited partners' operating partnership units to ESRT partner's capital	$ 31,660	$ 11,087

Description of Business and Org

Description of Business and Organization	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Organization	Description of Business and Organization As used in these condensed consolidated financial statements, unless the context otherwise requires, “we,” “us,” "our," and the "company,” mean Empire State Realty OP, L.P. and its consolidated subsidiaries. Empire State Realty OP, L.P. (the "Operating Partnership") is the entity through which Empire State Realty Trust, Inc. (“ESRT”), a self-administered and self-managed real estate investment trust ("REIT"), conducts all of its business and owns (either directly or through subsidiaries) substantially all of its assets. We own, manage, operate, acquire and reposition office and retail properties in Manhattan and the greater New York metropolitan area. As of September 30, 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 interests) encompassing approximately 9.4 million rentable square feet of office space. Nine of these properties are located in the midtown Manhattan market and 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 513,437 rentable square feet of retail space on their ground floor and/or contiguous levels. Our remaining five office properties are located in Fairfield County, Connecticut and Westchester County, New York, encompassing in the aggregate approximately 1.9 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. As of September 30, 2018 , our portfolio 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. We were organized as a Delaware limited partnership on November 28, 2011 and operations commenced upon completion of the initial public offering of ESRT’s Class A common stock and related formation transactions on October 7, 2013. ESRT, as the sole general partner in our company, has responsibility and discretion in the management and control of our company, and our limited partners, in such capacity, have no authority to transact business for, or participate in the management activities, of our company. As of September 30, 2018 , ESRT owned approximately 55.8% of our operating partnership units.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies There have been no material changes to the summary of significant accounting policies included in the section entitled "Summary of Significant Accounting Policies" in our December 31, 2017 Annual Report on Form 10-K. Basis of Quarterly Presentation and Principles of Consolidation The accompanying unaudited condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”), for interim financial information, and with the rules and regulations of the Securities and Exchange Commission (the "SEC"). Accordingly, certain information and footnote disclosures required by GAAP for complete financial statements have been condensed or omitted in accordance with such rules and regulations. In the opinion of management, all adjustments and eliminations (including intercompany balances and transactions), consisting of normal recurring adjustments, considered necessary for the fair presentation of the financial statements have been included. The results of operations for the periods presented are not necessarily indicative of the results that may be expected for the corresponding full years. These financial statements should be read in conjunction with the financial statements and accompanying notes included in the financial statements for the year ended December 31, 2017 contained in our Annual Report on Form 10-K. We do not consider our business to be subject to material seasonal fluctuations, except that our observatory business is subject to tourism seasonality. During the past ten years, approximately 16.0% to 18.0% of our annual observatory revenue was realized in the first quarter, 26.0% to 28.0% was realized in the second quarter, 31.0% to 33.0% was realized in the third quarter and 23.0% to 25.0% was realized in the fourth quarter. 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. For variable interest entities ("VIE"), we consolidate the entity if we are deemed to have a variable interest in the entity and through that interest we are deemed 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. We had no VIEs as of September 30, 2018 and December 31, 2017. 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 condensed consolidated balance sheets and in the condensed 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 condensed 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, valuation of the allowance for doubtful accounts, and valuation of derivative instruments, senior unsecured notes, mortgage notes payable, unsecured term loan and revolving credit 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. 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. The fair values of these investments approximate their carrying values. Reclassification The prior year 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 business. This screen reduces the number of transactions that need to be further evaluated. Real estate acquisitions that do not meet the definition of a business will be accounted for as asset acquisitions and the corresponding acquisition costs will be capitalized rather than expensed. 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 is effective for annual periods beginning after December 15, 2017, including interim periods within those periods. The amendments are applied prospectively on or after the effective date. No disclosures are required at transition. We believe that acquisitions of real estate properties will generally 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 is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. 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 is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. 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. ASU No. 2016-13 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 September 30, 2018 , the remaining contractual payments under our ground lease agreements aggregated $76.3 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 $4.5 million for the year ended December 31, 2017. 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. For entities that have not yet adopted ASU No. 2016-02, the effective dates and transition requirements for ASU No. 2018-10 and ASU 2018-11 will be the same as the effective date and transition requirements in ASU No. 2016-02. We continue to evaluate the impact of adopting these new accounting standards on our consolidated financial statements. During May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers, 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 Lease

Deferred Costs, Acquired Lease Intangibles and Goodwill	9 Months Ended
	Sep. 30, 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 as of September 30, 2018 and December 31, 2017 (amounts in thousands): September 30, 2018 December 31, 2017 Leasing costs $ 171,865 $ 164,751 Acquired in-place lease value and deferred leasing costs 218,810 237,364 Acquired above-market leases 53,208 67,415 443,883 469,530 Less: accumulated amortization (206,210 ) (215,102 ) Total deferred costs, net, excluding net deferred financing costs $ 237,673 $ 254,428 At September 30, 2018 and December 31, 2017, $6.8 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 condensed consolidated balance sheet. Amortization expense related to deferred leasing costs and acquired deferred leasing costs was $6.3 million and $5.8 million for the three months ended September 30, 2018 and 2017, respectively, and $18.4 million and $17.9 million for the nine months ended September 30, 2018 and 2017, respectively. Amortization expense related to acquired lease intangibles was $2.9 million and $4.0 million for the three months ended September 30, 2018 and 2017, respectively, and $9.3 million and $13.0 million for the nine months ended September 30, 2018 and 2017, respectively. Amortizing acquired intangible assets and liabilities consisted of the following as of September 30, 2018 and December 31, 2017 (amounts in thousands): September 30, 2018 December 31, 2017 Acquired below-market ground leases $ 396,916 $ 396,916 Less: accumulated amortization (34,561 ) (28,687 ) Acquired below-market ground leases, net $ 362,355 $ 368,229 September 30, 2018 December 31, 2017 Acquired below-market leases $ (120,568 ) $ (132,026 ) Less: accumulated amortization 64,906 65,979 Acquired below-market leases, net $ (55,662 ) $ (66,047 ) Rental revenue related to the amortization of below-market leases, net of above-market leases, was $1.7 million and $1.6 million for the three months ended September 30, 2018 and 2017, respectively, and $4.4 million and $4.1 million for the nine months ended September 30, 2018 and 2017, respectively. As of September 30, 2018 , we had goodwill of $491.5 million . Goodwill was allocated $227.5 million to the observatory reportable segment and $264.0 million to the real estate segment.

Debt

Debt	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Debt	Debt Debt consisted of the following as of September 30, 2018 and December 31, 2017 (amounts in thousands): Principal Balance As of September 30, 2018 September 30, 2018 December 31, 2017 Stated Effective (1) Maturity (2) Mortgage debt collateralized by: Fixed rate mortgage debt Metro Center $ 92,372 $ 93,948 3.59 % 3.66 % 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 % 4.44 % 7/1/2027 1010 Third Avenue and 77 West 55th Street 39,177 39,710 4.01 % 4.20 % 1/5/2028 10 Bank Street 33,988 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 % 4.26 % 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 615,537 721,224 Senior unsecured notes - exchangeable 250,000 250,000 2.63 % 3.93 % 8/15/2019 Senior unsecured notes: (6) 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 (6) — — (4) (4) 8/29/2021 Unsecured term loan facility (6) 265,000 265,000 (5) (5) 8/29/2022 Total principal 1,930,537 1,701,224 Unamortized discount, net of unamortized premium (2,315 ) (3,370 ) Deferred financing costs, net (9,538 ) (9,133 ) Total $ 1,918,684 $ 1,688,721 ______________ (1) The effective rate is the yield as of September 30, 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 at 4.09% and a $16 million loan bearing interest at 6.25% . (4) At September 30, 2018 , the unsecured revolving credit facility bears a floating rate at 30 day LIBOR plus 1.10% . The rate at September 30, 2018 was 3.36% . (5) 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 September 30, 2018 was 3.35% . (6) At September 30, 2018 , we were in compliance with all debt covenants. Mortgage Debt During January 2018, we refinanced and increased our mortgage debt on 1333 Broadway from $66.6 million to $160.0 million , due February 2033 with interest fixed at 4.21% . A portion of this increase was applied to release the $75.8 million mortgage lien on 1400 Broadway. Principal Payments Aggregate required principal payments at September 30, 2018 are as follows (amounts in thousands): Year Amortization Maturities Total 2018 $ 925 $ — $ 925 2019 3,790 250,000 253,790 2020 3,938 — 3,938 2021 4,090 — 4,090 2022 5,628 265,000 270,628 Thereafter 41,744 1,355,422 1,397,166 Total $ 60,115 $ 1,870,422 $ 1,930,537 Deferred Financing Costs Deferred financing costs, net, consisted of the following at September 30, 2018 and December 31, 2017 (amounts in thousands): September 30, 2018 December 31, 2017 Financing costs $ 25,312 $ 24,446 Less: accumulated amortization (9,006 ) (7,039 ) Total deferred financing costs, net $ 16,306 $ 17,407 At September 30, 2018 and December 31, 2017, $6.8 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 condensed consolidated balance sheet. Amortization expense related to deferred financing costs was $1.1 million and $1.0 million for the three months ended September 30, 2018 and 2017, respectively, and $3.1 million and $3.6 million for the nine months ended September 30, 2018 and 2017, respectively, and was included in interest expense. Unsecured Revolving Credit and Term Loan Facility During August 2017, 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 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 million term loan facility. 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. T he 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. Exchangeable Senior Notes Issued in August 2014, the $250.0 million 2.625% Exchangeable Senior Notes (“ 2.625% Exchangeable Senior Notes”) are due August 15, 2019. 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 that it is our intent and ability to settle the principal amount of the 2.625% Exchangeable Senior Notes in cash. As of September 30, 2018 , the exchange rate of the 2.625% Exchangeable Senior Notes was 51.9443 shares per $1,000 principal amount of notes (equivalent to an initial exchange price of approximately $19.25 per share of Class A common stock), subject to adjustment, as described in the related indenture governing the 2.625% Exchangeable Senior Notes. For the three and nine months ended September 30, 2018 , total interest expense related to the 2.625% Exchangeable Senior Notes was $2.4 million and $7.3 million , respectively, consisting of (i) the contractual interest expense of $1.6 million and $4.9 million , respectively, (ii) the additional non-cash interest expense of $0.7 million and $2.0 million , respectively, relating to the accretion of the debt discount, and (iii) the amortization of deferred financing costs of $0.1 million and $0.4 million , respectively. For the three and nine months ended September 30, 2017 , total interest expense related to the 2.625% Exchangeable Senior Notes was $2.4 million and $7.3 million , respectively, consisting of (i) the contractual interest expense of $1.6 million and $4.9 million , respectively, (ii) the additional non-cash interest expense of $0.7 million and $2.0 million , respectively, relating to the accretion of the debt discount, and (iii) the amortization of deferred financing costs of $0.1 million and $0.4 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, before their maturity dates in early April 2018.

Accounts Payable and Accrued Ex

Accounts Payable and Accrued Expenses	9 Months Ended
	Sep. 30, 2018
Payables and Accruals [Abstract]
Accounts Payable and Accrued Expenses	Accounts Payable and Accrued Expenses Accounts payable and accrued expenses consisted of the following as of September 30, 2018 and December 31, 2017 (amounts in thousands): September 30, 2018 December 31, 2017 Accrued capital expenditures $ 92,506 $ 71,769 Accounts payable and accrued expenses 31,841 32,509 Interest rate swap agreements liability — 436 Accrued interest payable 3,447 5,687 Due to affiliated companies 546 448 Total accounts payable and accrued expenses $ 128,340 $ 110,849

Financial Instruments and Fair

Financial Instruments and Fair Values	9 Months Ended
	Sep. 30, 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 September 30, 2018 , we did not have any derivatives in a net liability position. As of September 30, 2018 and December 31, 2017, we had interest rate LIBOR swaps with an aggregate notional value of $515.0 million and $265.0 million , respectively. The notional value does not represent exposure to credit, interest rate or market risks. As of September 30, 2018 , the fair value of our derivative instruments amounted to $9.9 million which is included in prepaid expenses and other assets on the condensed consolidated balance sheet. As of December 31, 2017, the fair value of our derivative instruments amounted to $(0.4) million which was included in accounts payable and accrued expenses on the condensed consolidated balance sheet. These interest rate swaps have been designated as cash flow hedges and hedge the future cash outflows on our exchangeable senior notes and also on our term loan facility that is subject to a floating interest rate. As of September 30, 2018 and 2017, our cash flow hedges are deemed highly effective and a net unrealized gain (loss) of $4.3 million and $(1.3) million for the three months ended September 30, 2018 and 2017, respectively, and a net unrealized gain (loss) of $11.4 million and $(14.3) million for the nine months ended September 30, 2018 and 2017, respectively, are reflected in the condensed consolidated statements of comprehensive income. 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 $(2.3) million of the current balance held in accumulated other comprehensive income (loss) will be reclassified into interest expense within the next 12 months relating to interest rate swap contracts in effect as of September 30, 2018 . As of September 30, 2018 and December 31, 2017, the deferred net losses from terminated hedges amounted to $14.1 million and $15.1 million , respectively, which are included in accumulated other comprehensive income (loss) related to derivatives. We will reclassify into earnings, as an increase to interest expense, approximately $1.5 million within the next 12 months related to the deferred losses from the terminated hedges. For the nine months ended September 30, 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 on a $20.0 million notional amount. The table below summarizes the terms of agreements and the fair values of our derivative financial instruments as of September 30, 2018 and December 31, 2017 (dollar amounts in thousands): September 30, 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 $ 7,300 $ — $ — $ (436 ) Interest rate swap 125,000 3 Month LIBOR 2.9580% July 1, 2019 July 1, 2026 1,316 — — — Interest rate swap 125,000 3 Month LIBOR 2.9580% July 1, 2019 July 1, 2026 1,328 — — — $ 9,944 $ — $ — $ (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 three and nine months ended September 30, 2018 and 2017 (amounts in thousands): Three Months Ended Nine Months Ended Effects of Cash Flow Hedges September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Amount of gain (loss) recognized in other comprehensive income (loss) $ 3,884 $ (1,638 ) $ 9,827 $ (14,654 ) Amount of gain (loss) reclassified from accumulated other comprehensive income (loss) into interest expense (427 ) (359 ) (1,562 ) (402 ) The table below shows the effect of our derivative financial instruments designated as cash flow hedges on the condensed consolidated statements of income for the three and nine months ended September 30, 2018 and 2017 (amounts in thousands): Three Months Ended Nine Months Ended Effects of Cash Flow Hedges September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Total interest (expense) presented in the condensed consolidated statements of income in which the effects of cash flow hedges are recorded $ (20,658 ) $ (16,890 ) $ (58,774 ) $ (52,109 ) Amount of gain (loss) reclassified from accumulated other comprehensive income (loss) into interest expense (427 ) (359 ) (1,562 ) (402 ) Fair Valuation The estimated fair values at September 30, 2018 and December 31, 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 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, senior unsecured notes - Series A, B, C, D, E and F, and unsecured term loan facility 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. The following tables summarize the carrying and estimated fair values of our financial instruments as of September 30, 2018 and December 31, 2017 (amounts in thousands): September 30, 2018 Estimated Fair Value Carrying Total Level 1 Level 2 Level 3 Interest rate swaps included in prepaid expenses and other assets $ 9,944 $ 9,944 $ — $ 9,944 $ — Interest rate swaps included in accounts payable and accrued expenses — — — — — Mortgage notes payable 609,299 574,238 — — 574,238 Senior unsecured notes - Exchangeable 247,114 251,563 — 251,563 — Senior unsecured notes - Series A, B, C, D, E and F 798,248 773,375 — — 773,375 Unsecured term loan facility 264,023 265,000 — — 265,000 December 31, 2017 Estimated Fair Value Carrying 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 and D 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 September 30, 2018 and December 31, 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	9 Months Ended
	Sep. 30, 2018
Leases [Abstract]
Rental Income	Rental Income We lease various spaces to tenants over terms ranging from one to 21 years. 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 condensed consolidated statements of income as tenant expense reimbursement.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal Proceedings Except as described below, as of September 30, 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 January 17, 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. Unfunded Capital Expenditures At September 30, 2018 , we estimate that we will incur approximately $91.5 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. Ground Leases Aggregate requir ed payments on ground leases at September 30, 2018 were as follows (amounts in thousands): 2018 $ 380 2019 1,518 2020 1,518 2021 1,518 2022 1,518 Thereafter 69,816 $ 76,268 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 September 30, 2018 , we held on deposit at various major financial institutions cash and cash equivalents, restricted cash and short-term investment balances in excess of amounts insured by the Federal Deposit Insurance Corporation. 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 September 30, 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 September 30, 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 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.

Capital

Capital	9 Months Ended
	Sep. 30, 2018
Stockholders' Equity Note Disclosure, Disclosure of Compensation Related Costs, Share-based Payments and Earnings Per Share [Abstract]
Capital	Capital As of September 30, 2018 , there were 303,333,599 operating partnership units outstanding, of which 169,220,903 , or 55.8% , were owned by ESRT and 134,112,696 , or 44.2% , were owned by other partners, including ESRT directors, members of senior management and other employees. Long-term incentive plan ("LTIP") units are a special class of partnership interests. Each LTIP unit awarded will be deemed equivalent to an award of one share of ESRT stock under the First Amended and Restated Empire State Realty Trust, Inc. and 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, we 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 unitholders. Subject to any agreed upon exceptions, once vested and having achieved parity with unitholders, LTIP units are convertible into Series PR operating partnership units on a one-for-one basis. LTIP units subject to time based vesting, whether vested or not, receive the same per unit distributions as operating partnership units, which equal per share dividends (both regular and special) on our common stock. Performance 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. Distributions Total distributions paid to OP unitholders were $31.9 million and $95.3 million for the three and nine months ended September 30, 2018 , respectively, and $31.5 million and $94.5 million for the three and nine months ended September 30, 2017, respectively. Total distributions paid to preferred unitholders were $0.2 million and $0.7 million for the three and nine months ended September 30, 2018 , respectively, and $0.2 million and $0.7 million for the three and nine months ended September 30, 2017, respectively. Incentive and Share-Based Compensation The 2013 Plan provides for grants to 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 12.2 million shares of ESRT common stock is authorized for issuance under awards granted pursuant to the 2013 Plan, and as of September 30, 2018 , 4.3 million shares of ESRT common stock remain available for future issuance. 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 performance-based vesting, with fair market values of $6.1 million for the time-based vesting awards and $9.6 million for the performance-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 performance-based vesting, with fair market values of $1.7 million for the time-based vesting awards and $1.1 million for the performance-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 of $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 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. 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 performance-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 ESRT restricted stock issued during the nine months ended September 30, 2018 were valued at $23.6 million . The weighted-average per unit or share fair value was $8.54 for grants issued in 2018. The per unit or share granted in 2018 was estimated on the respective dates of grant using the following assumptions: an expected life of 5.6 years, a dividend rate of 2.30% , a risk-free interest rate of 2.50% , and an expected price volatility of 17.0% . No other stock options, dividend equivalents, or stock appreciation rights were issued or outstanding in 2018. The following is a summary of ESRT restricted stock and LTIP unit activity for the nine months ended September 30, 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 ) (492,877 ) 14.58 Granted 39,608 2,719,801 8.54 Forfeited or unearned (7,811 ) (103,490 ) 8.52 Unvested balance at September 30, 2018 91,895 5,712,043 $ 9.68 The LTIP unit and ESRT restricted stock awards will immediately vest upon the later of (i) the date the grantee attains the age of 60 and (ii) the date on which grantee has first completed ten years of continuous service with our company or its 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 performance-based awards, and accordingly, we recognized $0.4 million and $1.7 million for the three and nine months ended September 30, 2018 , respectively, and $0.2 million and $0.9 million for the three and nine months ended September 30, 2017, respectively. Unrecognized compensation expense was $1.2 million at September 30, 2018 , which will be recognized over a weighted average period of 2.2 years. For the remainder of the LTIP unit and ESRT restricted stock awards, we recognize noncash compensation expense ratably over the vesting period, and accordingly, we recognized noncash compensation expense of $4.5 million and $12.4 million for the three and nine months ended September 30, 2018 , respectively, and $3.7 million and $9.9 million for the three and nine months ended September 30, 2017, respectively. Unrecognized compensation expense was $32.0 million at September 30, 2018 , which will be recognized over a weighted average period of 2.3 years. Earnings Per Unit Earnings per unit for the three and nine months ended September 30, 2018 and 2017 is computed as follows (amounts in thousands, except per share amounts): Three Months Ended, Nine Months Ended, September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Numerator: Net income $ 29,230 $ 35,489 $ 77,472 $ 85,993 Private perpetual preferred unit distributions (234 ) (234 ) (702 ) (702 ) Earnings allocated to unvested units (212 ) (228 ) (586 ) (582 ) Net income attributable to common unitholders - basic and diluted $ 28,784 $ 35,027 $ 76,184 $ 84,709 Denominator: Weighted average units outstanding - basic 297,478 296,389 297,180 296,389 Effect of dilutive securities: Stock-based compensation plans — 762 1 848 Exchangeable senior notes — 720 — 852 Weighted average units outstanding - diluted 297,478 297,871 297,181 298,089 Earnings per share: Basic $ 0.10 $ 0.12 $ 0.26 $ 0.29 Diluted $ 0.10 $ 0.12 $ 0.26 $ 0.28 There were 541,947 and 458,698 antidilutive shares and LTIP units for the three and nine months ended September 30, 2018 , respectively, and 954,533 and 840,092 antidilutive shares and LTIP units for the three and nine months ended September 30, 2017, respectively.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2018
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Supervisory Fee Revenue We earned supervisory fees from entities affiliated with Anthony E. Malkin, our Chairman and Chief Executive Officer, of $0.2 million and $0.3 million for the three months ended September 30, 2018 and 2017, respectively, and $0.9 million and $0.9 million for the nine months ended September 30, 2018 and 2017, respectively. These fees are included within third-party management and other fees. Property Management Fee Revenue We earned property management fees from entities affiliated with Anthony E. Malkin of $0.1 million and $0.1 million for the three months ended September 30, 2018 and 2017, respectively, and $0.3 million and $0.2 million for the nine months ended September 30, 2018 and 2017, respectively. These fees are included within third-party management and other fees. Other We receive rent generally at market rental rate for 5,351 square feet of leased space from entities affiliated with Anthony E. Malkin at one of our properties. Under the lease, the tenant has the right to cancel such lease without special payment on 90 days’ notice. We also 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 to provide them with general computer-related support. Total revenue aggregated $0.1 million and $0.1 million for the three months ended September 30, 2018 and 2017, respectively, and $0.3 million and $0.3 million for the nine months ended September 30, 2018 and 2017, respectively. One of ESRT's 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 $4.1 million as of September 30, 2018 .

Segment Reporting

Segment Reporting	9 Months Ended
	Sep. 30, 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, redevelopment, repositioning and disposition of our real estate assets. Our observatory segment includes the operation of 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 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. The following tables provide components of segment profit for each segment for the three and nine months ended September 30, 2018 and 2017 (amounts in thousands): Three Months Ended September 30, 2018 Real Estate Observatory Intersegment Elimination Total Revenues: Rental revenue $ 123,621 $ — $ — $ 123,621 Intercompany rental revenue 23,805 — (23,805 ) — Tenant expense reimbursement 18,627 — — 18,627 Observatory revenue — 40,241 — 40,241 Lease termination fees 1,185 — — 1,185 Third-party management and other fees 312 — — 312 Other revenue and fees 2,416 — — 2,416 Total revenues 169,966 40,241 (23,805 ) 186,402 Operating expenses: Property operating expenses 42,772 — — 42,772 Intercompany rent expense — 23,805 (23,805 ) — Ground rent expense 2,331 — — 2,331 General and administrative expenses 13,148 — — 13,148 Observatory expenses — 8,854 — 8,854 Real estate taxes 28,284 — — 28,284 Depreciation and amortization 42,458 17 — 42,475 Total operating expenses 128,993 32,676 (23,805 ) 137,864 Total operating income 40,973 7,565 — 48,538 Other income (expense): Interest income 3,485 — — 3,485 Interest expense (20,658 ) — — (20,658 ) Income before income taxes 23,800 7,565 — 31,365 Income tax expense (277 ) (1,858 ) — (2,135 ) Net income $ 23,523 $ 5,707 $ — $ 29,230 Segment assets $ 3,904,454 $ 262,378 $ — $ 4,166,832 Expenditures for segment assets $ 52,613 $ 14,507 $ — $ 67,120 Three Months Ended September 30, 2017 Real Estate Observatory Intersegment Elimination Total Revenues: Rental revenue $ 122,391 $ — $ — $ 122,391 Intercompany rental revenue 23,301 — (23,301 ) — Tenant expense reimbursement 20,346 — — 20,346 Observatory revenue — 39,306 — 39,306 Lease termination fees 1,165 — — 1,165 Third-party management and other fees 345 — — 345 Other revenue and fees 2,993 — — 2,993 Total revenues 170,541 39,306 (23,301 ) 186,546 Operating expenses: Property operating expenses 41,270 — — 41,270 Intercompany rent expense — 23,301 (23,301 ) — Ground rent expense 2,331 — — 2,331 General and administrative expenses 12,899 — — 12,899 Observatory expenses — 8,648 — 8,648 Real estate taxes 26,901 — — 26,901 Depreciation and amortization 38,473 17 — 38,490 Total operating expenses 121,874 31,966 (23,301 ) 130,539 Total operating income 48,667 7,340 — 56,007 Other income (expense): Interest income 774 — — 774 Interest expense (16,890 ) — — (16,890 ) Loss on early extinguishment of debt (2,157 ) — — (2,157 ) Income before income taxes 30,394 7,340 — 37,734 Income tax expense (264 ) (1,981 ) — (2,245 ) Net income $ 30,130 $ 5,359 $ — $ 35,489 Segment assets $ 3,582,935 $ 265,999 $ — $ 3,848,934 Expenditures for segment assets $ 40,320 $ 13,411 $ — $ 53,731 Nine Months Ended September 30, 2018 Real Estate Observatory Intersegment Elimination Total Revenues: Rental revenue $ 369,970 $ — $ — $ 369,970 Intercompany rental revenue 59,356 — (59,356 ) — Tenant expense reimbursement 52,626 — — 52,626 Observatory revenue — 96,691 — 96,691 Lease termination fees 2,164 — — 2,164 Third-party management and other fees 1,151 — — 1,151 Other revenue and fees 9,600 — — 9,600 Total revenues 494,867 96,691 (59,356 ) 532,202 Operating expenses: Property operating expenses 126,375 — — 126,375 Intercompany rent expense — 59,356 (59,356 ) — Ground rent expense 6,994 — — 6,994 General and administrative expenses 39,001 — — 39,001 Observatory expenses — 23,868 — 23,868 Real estate taxes 81,771 — — 81,771 Depreciation and amortization 121,775 51 — 121,826 Total operating expenses 375,916 83,275 (59,356 ) 399,835 Total operating income 118,951 13,416 — 132,367 Other income (expense): Interest income 7,209 — — 7,209 Interest expense (58,774 ) — — (58,774 ) Income before income taxes 67,386 13,416 — 80,802 Income tax expense (852 ) (2,478 ) — (3,330 ) Net income $ 66,534 $ 10,938 $ — $ 77,472 Expenditures for segment assets $ 148,429 $ 41,930 $ — $ 190,359 Nine Months Ended September 30, 2017 Real Estate Observatory Intersegment Elimination Total Revenues: Rental revenue $ 360,348 $ — $ — $ 360,348 Intercompany rental revenue 57,354 — (57,354 ) — Tenant expense reimbursement 53,889 — — 53,889 Observatory revenue — 94,212 — 94,212 Lease termination fees 10,354 — — 10,354 Third-party management and other fees 1,088 — — 1,088 Other revenue and fees 7,338 — — 7,338 Total revenues 490,371 94,212 (57,354 ) 527,229 Operating expenses: Property operating expenses 122,009 — — 122,009 Intercompany rent expense — 57,354 (57,354 ) — Ground rent expense 6,994 — — 6,994 General and administrative expenses 36,566 — — 36,566 Observatory expenses — 23,079 — 23,079 Real estate taxes 76,001 — — 76,001 Depreciation and amortization 119,764 104 — 119,868 Total operating expenses 361,334 80,537 (57,354 ) 384,517 Total operating income 129,037 13,675 — 142,712 Other income (expense): Interest income 2,169 — — 2,169 Interest expense (52,109 ) — — (52,109 ) Loss on early extinguishment of debt (2,157 ) — — (2,157 ) Loss from derivative financial instruments (289 ) — — (289 ) Income before income taxes 76,651 13,675 — 90,326 Income tax expense (960 ) (3,373 ) — (4,333 ) Net income $ 75,691 $ 10,302 $ — $ 85,993 Expenditures for segment assets $ 142,854 $ 20,261 $ — $ 163,115

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2018
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events None.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Basis of Quarterly Presentation	The accompanying unaudited condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”), for interim financial information, and with the rules and regulations of the Securities and Exchange Commission (the "SEC"). Accordingly, certain information and footnote disclosures required by GAAP for complete financial statements have been condensed or omitted in accordance with such rules and regulations. In the opinion of management, all adjustments and eliminations (including intercompany balances and transactions), consisting of normal recurring adjustments, considered necessary for the fair presentation of the financial statements have been included.
Principles of Consolidation	The results of operations for the periods presented are not necessarily indicative of the results that may be expected for the corresponding full years. These financial statements should be read in conjunction with the financial statements and accompanying notes included in the financial statements for the year ended December 31, 2017 contained in our Annual Report on Form 10-K. We do not consider our business to be subject to material seasonal fluctuations, except that our observatory business is subject to tourism seasonality.
Principles of Consolidation for Variable Interest Entities	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. For variable interest entities ("VIE"), we consolidate the entity if we are deemed to have a variable interest in the entity and through that interest we are deemed 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. We had no VIEs as of September 30, 2018 and December 31, 2017. 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 condensed consolidated balance sheets and in the condensed 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 condensed 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, valuation of the allowance for doubtful accounts, and valuation of derivative instruments, senior unsecured notes, mortgage notes payable, unsecured term loan and revolving credit 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.
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. The fair values of these investments approximate their carrying values.
Reclassification	The prior year 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 business. This screen reduces the number of transactions that need to be further evaluated. Real estate acquisitions that do not meet the definition of a business will be accounted for as asset acquisitions and the corresponding acquisition costs will be capitalized rather than expensed. 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 is effective for annual periods beginning after December 15, 2017, including interim periods within those periods. The amendments are applied prospectively on or after the effective date. No disclosures are required at transition. We believe that acquisitions of real estate properties will generally 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 is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. 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 is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. 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. ASU No. 2016-13 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 September 30, 2018 , the remaining contractual payments under our ground lease agreements aggregated $76.3 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 $4.5 million for the year ended December 31, 2017. 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. For entities that have not yet adopted ASU No. 2016-02, the effective dates and transition requirements for ASU No. 2018-10 and ASU 2018-11 will be the same as the effective date and transition requirements in ASU No. 2016-02. We continue to evaluate the impact of adopting these new accounting standards on our consolidated financial statements. During May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers, 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)	9 Months Ended
	Sep. 30, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Deferred Costs, Net	Deferred costs, net, consisted of the following as of September 30, 2018 and December 31, 2017 (amounts in thousands): September 30, 2018 December 31, 2017 Leasing costs $ 171,865 $ 164,751 Acquired in-place lease value and deferred leasing costs 218,810 237,364 Acquired above-market leases 53,208 67,415 443,883 469,530 Less: accumulated amortization (206,210 ) (215,102 ) Total deferred costs, net, excluding net deferred financing costs $ 237,673 $ 254,428 Deferred financing costs, net, consisted of the following at September 30, 2018 and December 31, 2017 (amounts in thousands): September 30, 2018 December 31, 2017 Financing costs $ 25,312 $ 24,446 Less: accumulated amortization (9,006 ) (7,039 ) Total deferred financing costs, net $ 16,306 $ 17,407
Amortizing Acquired Intangible Assets and Liabilities	Amortizing acquired intangible assets and liabilities consisted of the following as of September 30, 2018 and December 31, 2017 (amounts in thousands): September 30, 2018 December 31, 2017 Acquired below-market ground leases $ 396,916 $ 396,916 Less: accumulated amortization (34,561 ) (28,687 ) Acquired below-market ground leases, net $ 362,355 $ 368,229 September 30, 2018 December 31, 2017 Acquired below-market leases $ (120,568 ) $ (132,026 ) Less: accumulated amortization 64,906 65,979 Acquired below-market leases, net $ (55,662 ) $ (66,047 )

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Long-Term Debt	Debt consisted of the following as of September 30, 2018 and December 31, 2017 (amounts in thousands): Principal Balance As of September 30, 2018 September 30, 2018 December 31, 2017 Stated Effective (1) Maturity (2) Mortgage debt collateralized by: Fixed rate mortgage debt Metro Center $ 92,372 $ 93,948 3.59 % 3.66 % 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 % 4.44 % 7/1/2027 1010 Third Avenue and 77 West 55th Street 39,177 39,710 4.01 % 4.20 % 1/5/2028 10 Bank Street 33,988 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 % 4.26 % 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 615,537 721,224 Senior unsecured notes - exchangeable 250,000 250,000 2.63 % 3.93 % 8/15/2019 Senior unsecured notes: (6) 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 (6) — — (4) (4) 8/29/2021 Unsecured term loan facility (6) 265,000 265,000 (5) (5) 8/29/2022 Total principal 1,930,537 1,701,224 Unamortized discount, net of unamortized premium (2,315 ) (3,370 ) Deferred financing costs, net (9,538 ) (9,133 ) Total $ 1,918,684 $ 1,688,721 ______________ (1) The effective rate is the yield as of September 30, 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 at 4.09% and a $16 million loan bearing interest at 6.25% . (4) At September 30, 2018 , the unsecured revolving credit facility bears a floating rate at 30 day LIBOR plus 1.10% . The rate at September 30, 2018 was 3.36% . (5) 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 September 30, 2018 was 3.35% . (6) At September 30, 2018 , we were in compliance with all debt covenants.
Aggregate Required Principal Payments	Aggregate required principal payments at September 30, 2018 are as follows (amounts in thousands): Year Amortization Maturities Total 2018 $ 925 $ — $ 925 2019 3,790 250,000 253,790 2020 3,938 — 3,938 2021 4,090 — 4,090 2022 5,628 265,000 270,628 Thereafter 41,744 1,355,422 1,397,166 Total $ 60,115 $ 1,870,422 $ 1,930,537
Deferred Costs, Net	Deferred costs, net, consisted of the following as of September 30, 2018 and December 31, 2017 (amounts in thousands): September 30, 2018 December 31, 2017 Leasing costs $ 171,865 $ 164,751 Acquired in-place lease value and deferred leasing costs 218,810 237,364 Acquired above-market leases 53,208 67,415 443,883 469,530 Less: accumulated amortization (206,210 ) (215,102 ) Total deferred costs, net, excluding net deferred financing costs $ 237,673 $ 254,428 Deferred financing costs, net, consisted of the following at September 30, 2018 and December 31, 2017 (amounts in thousands): September 30, 2018 December 31, 2017 Financing costs $ 25,312 $ 24,446 Less: accumulated amortization (9,006 ) (7,039 ) Total deferred financing costs, net $ 16,306 $ 17,407

Accounts Payable and Accrued _2

Accounts Payable and Accrued Expenses (Tables)	9 Months Ended
	Sep. 30, 2018
Payables and Accruals [Abstract]
Accounts Payable and Accrued Expenses	Accounts payable and accrued expenses consisted of the following as of September 30, 2018 and December 31, 2017 (amounts in thousands): September 30, 2018 December 31, 2017 Accrued capital expenditures $ 92,506 $ 71,769 Accounts payable and accrued expenses 31,841 32,509 Interest rate swap agreements liability — 436 Accrued interest payable 3,447 5,687 Due to affiliated companies 546 448 Total accounts payable and accrued expenses $ 128,340 $ 110,849

Financial Instruments and Fai_2

Financial Instruments and Fair Values (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Summary of the Terms of Agreements and the Fair Value of Derivative Financial Instruments	The table below summarizes the terms of agreements and the fair values of our derivative financial instruments as of September 30, 2018 and December 31, 2017 (dollar amounts in thousands): September 30, 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 $ 7,300 $ — $ — $ (436 ) Interest rate swap 125,000 3 Month LIBOR 2.9580% July 1, 2019 July 1, 2026 1,316 — — — Interest rate swap 125,000 3 Month LIBOR 2.9580% July 1, 2019 July 1, 2026 1,328 — — — $ 9,944 $ — $ — $ (436 )
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 three and nine months ended September 30, 2018 and 2017 (amounts in thousands): Three Months Ended Nine Months Ended Effects of Cash Flow Hedges September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Amount of gain (loss) recognized in other comprehensive income (loss) $ 3,884 $ (1,638 ) $ 9,827 $ (14,654 ) Amount of gain (loss) reclassified from accumulated other comprehensive income (loss) into interest expense (427 ) (359 ) (1,562 ) (402 ) The table below shows the effect of our derivative financial instruments designated as cash flow hedges on the condensed consolidated statements of income for the three and nine months ended September 30, 2018 and 2017 (amounts in thousands): Three Months Ended Nine Months Ended Effects of Cash Flow Hedges September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Total interest (expense) presented in the condensed consolidated statements of income in which the effects of cash flow hedges are recorded $ (20,658 ) $ (16,890 ) $ (58,774 ) $ (52,109 ) Amount of gain (loss) reclassified from accumulated other comprehensive income (loss) into interest expense (427 ) (359 ) (1,562 ) (402 )
Summary of the Carrying and Estimated Fair Values of Financial Instruments	The following tables summarize the carrying and estimated fair values of our financial instruments as of September 30, 2018 and December 31, 2017 (amounts in thousands): September 30, 2018 Estimated Fair Value Carrying Total Level 1 Level 2 Level 3 Interest rate swaps included in prepaid expenses and other assets $ 9,944 $ 9,944 $ — $ 9,944 $ — Interest rate swaps included in accounts payable and accrued expenses — — — — — Mortgage notes payable 609,299 574,238 — — 574,238 Senior unsecured notes - Exchangeable 247,114 251,563 — 251,563 — Senior unsecured notes - Series A, B, C, D, E and F 798,248 773,375 — — 773,375 Unsecured term loan facility 264,023 265,000 — — 265,000 December 31, 2017 Estimated Fair Value Carrying 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 and D 463,156 460,352 — — 460,352 Unsecured term loan facility 263,662 265,000 — — 265,000

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Aggregate Required Payments on Ground Leases	Aggregate requir ed payments on ground leases at September 30, 2018 were as follows (amounts in thousands): 2018 $ 380 2019 1,518 2020 1,518 2021 1,518 2022 1,518 Thereafter 69,816 $ 76,268

Capital (Tables)

Capital (Tables)	9 Months Ended
	Sep. 30, 2018
Stockholders' Equity Note Disclosure, Disclosure of Compensation Related Costs, Share-based Payments and Earnings Per Share [Abstract]
Summary of ERST Restricted Stock and LTIP Unit	The following is a summary of ESRT restricted stock and LTIP unit activity for the nine months ended September 30, 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 ) (492,877 ) 14.58 Granted 39,608 2,719,801 8.54 Forfeited or unearned (7,811 ) (103,490 ) 8.52 Unvested balance at September 30, 2018 91,895 5,712,043 $ 9.68
Earnings Per Unit	Earnings per unit for the three and nine months ended September 30, 2018 and 2017 is computed as follows (amounts in thousands, except per share amounts): Three Months Ended, Nine Months Ended, September 30, 2018 September 30, 2017 September 30, 2018 September 30, 2017 Numerator: Net income $ 29,230 $ 35,489 $ 77,472 $ 85,993 Private perpetual preferred unit distributions (234 ) (234 ) (702 ) (702 ) Earnings allocated to unvested units (212 ) (228 ) (586 ) (582 ) Net income attributable to common unitholders - basic and diluted $ 28,784 $ 35,027 $ 76,184 $ 84,709 Denominator: Weighted average units outstanding - basic 297,478 296,389 297,180 296,389 Effect of dilutive securities: Stock-based compensation plans — 762 1 848 Exchangeable senior notes — 720 — 852 Weighted average units outstanding - diluted 297,478 297,871 297,181 298,089 Earnings per share: Basic $ 0.10 $ 0.12 $ 0.26 $ 0.29 Diluted $ 0.10 $ 0.12 $ 0.26 $ 0.28

Segment Reporting (Tables)

Segment Reporting (Tables)	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Components of Segment Profit for Each Segment	The following tables provide components of segment profit for each segment for the three and nine months ended September 30, 2018 and 2017 (amounts in thousands): Three Months Ended September 30, 2018 Real Estate Observatory Intersegment Elimination Total Revenues: Rental revenue $ 123,621 $ — $ — $ 123,621 Intercompany rental revenue 23,805 — (23,805 ) — Tenant expense reimbursement 18,627 — — 18,627 Observatory revenue — 40,241 — 40,241 Lease termination fees 1,185 — — 1,185 Third-party management and other fees 312 — — 312 Other revenue and fees 2,416 — — 2,416 Total revenues 169,966 40,241 (23,805 ) 186,402 Operating expenses: Property operating expenses 42,772 — — 42,772 Intercompany rent expense — 23,805 (23,805 ) — Ground rent expense 2,331 — — 2,331 General and administrative expenses 13,148 — — 13,148 Observatory expenses — 8,854 — 8,854 Real estate taxes 28,284 — — 28,284 Depreciation and amortization 42,458 17 — 42,475 Total operating expenses 128,993 32,676 (23,805 ) 137,864 Total operating income 40,973 7,565 — 48,538 Other income (expense): Interest income 3,485 — — 3,485 Interest expense (20,658 ) — — (20,658 ) Income before income taxes 23,800 7,565 — 31,365 Income tax expense (277 ) (1,858 ) — (2,135 ) Net income $ 23,523 $ 5,707 $ — $ 29,230 Segment assets $ 3,904,454 $ 262,378 $ — $ 4,166,832 Expenditures for segment assets $ 52,613 $ 14,507 $ — $ 67,120 Three Months Ended September 30, 2017 Real Estate Observatory Intersegment Elimination Total Revenues: Rental revenue $ 122,391 $ — $ — $ 122,391 Intercompany rental revenue 23,301 — (23,301 ) — Tenant expense reimbursement 20,346 — — 20,346 Observatory revenue — 39,306 — 39,306 Lease termination fees 1,165 — — 1,165 Third-party management and other fees 345 — — 345 Other revenue and fees 2,993 — — 2,993 Total revenues 170,541 39,306 (23,301 ) 186,546 Operating expenses: Property operating expenses 41,270 — — 41,270 Intercompany rent expense — 23,301 (23,301 ) — Ground rent expense 2,331 — — 2,331 General and administrative expenses 12,899 — — 12,899 Observatory expenses — 8,648 — 8,648 Real estate taxes 26,901 — — 26,901 Depreciation and amortization 38,473 17 — 38,490 Total operating expenses 121,874 31,966 (23,301 ) 130,539 Total operating income 48,667 7,340 — 56,007 Other income (expense): Interest income 774 — — 774 Interest expense (16,890 ) — — (16,890 ) Loss on early extinguishment of debt (2,157 ) — — (2,157 ) Income before income taxes 30,394 7,340 — 37,734 Income tax expense (264 ) (1,981 ) — (2,245 ) Net income $ 30,130 $ 5,359 $ — $ 35,489 Segment assets $ 3,582,935 $ 265,999 $ — $ 3,848,934 Expenditures for segment assets $ 40,320 $ 13,411 $ — $ 53,731 Nine Months Ended September 30, 2018 Real Estate Observatory Intersegment Elimination Total Revenues: Rental revenue $ 369,970 $ — $ — $ 369,970 Intercompany rental revenue 59,356 — (59,356 ) — Tenant expense reimbursement 52,626 — — 52,626 Observatory revenue — 96,691 — 96,691 Lease termination fees 2,164 — — 2,164 Third-party management and other fees 1,151 — — 1,151 Other revenue and fees 9,600 — — 9,600 Total revenues 494,867 96,691 (59,356 ) 532,202 Operating expenses: Property operating expenses 126,375 — — 126,375 Intercompany rent expense — 59,356 (59,356 ) — Ground rent expense 6,994 — — 6,994 General and administrative expenses 39,001 — — 39,001 Observatory expenses — 23,868 — 23,868 Real estate taxes 81,771 — — 81,771 Depreciation and amortization 121,775 51 — 121,826 Total operating expenses 375,916 83,275 (59,356 ) 399,835 Total operating income 118,951 13,416 — 132,367 Other income (expense): Interest income 7,209 — — 7,209 Interest expense (58,774 ) — — (58,774 ) Income before income taxes 67,386 13,416 — 80,802 Income tax expense (852 ) (2,478 ) — (3,330 ) Net income $ 66,534 $ 10,938 $ — $ 77,472 Expenditures for segment assets $ 148,429 $ 41,930 $ — $ 190,359 Nine Months Ended September 30, 2017 Real Estate Observatory Intersegment Elimination Total Revenues: Rental revenue $ 360,348 $ — $ — $ 360,348 Intercompany rental revenue 57,354 — (57,354 ) — Tenant expense reimbursement 53,889 — — 53,889 Observatory revenue — 94,212 — 94,212 Lease termination fees 10,354 — — 10,354 Third-party management and other fees 1,088 — — 1,088 Other revenue and fees 7,338 — — 7,338 Total revenues 490,371 94,212 (57,354 ) 527,229 Operating expenses: Property operating expenses 122,009 — — 122,009 Intercompany rent expense — 57,354 (57,354 ) — Ground rent expense 6,994 — — 6,994 General and administrative expenses 36,566 — — 36,566 Observatory expenses — 23,079 — 23,079 Real estate taxes 76,001 — — 76,001 Depreciation and amortization 119,764 104 — 119,868 Total operating expenses 361,334 80,537 (57,354 ) 384,517 Total operating income 129,037 13,675 — 142,712 Other income (expense): Interest income 2,169 — — 2,169 Interest expense (52,109 ) — — (52,109 ) Loss on early extinguishment of debt (2,157 ) — — (2,157 ) Loss from derivative financial instruments (289 ) — — (289 ) Income before income taxes 76,651 13,675 — 90,326 Income tax expense (960 ) (3,373 ) — (4,333 ) Net income $ 75,691 $ 10,302 $ — $ 85,993 Expenditures for segment assets $ 142,854 $ 20,261 $ — $ 163,115

Description of Business and O_2

Description of Business and Organization - Narrative (Details)	9 Months Ended
	Sep. 30, 2018ft²parceloffice_and_property
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Area of real estate property (in square feet)	10,100,000
OP units owned by the Company (as a percent)	55.80%
Office Building
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Area of real estate property (in square feet)	9,400,000
Number of properties | office_and_property	14
Office Building | Manhattan
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Area of real estate property (in square feet)	7,600,000
Number of properties | office_and_property	9
Office Building | Fairfield County, Connecticut and Westchester County, New York
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Area of real estate property (in square feet)	1,900,000
Number of properties | office_and_property	5
Development Parcel
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Number of properties | parcel	3
Retail Site | Manhattan and Westport, Connecticut
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Area of real estate property (in square feet)	205,748
Retail Site | Manhattan
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Area of real estate property (in square feet)	513,437
Number of properties | office_and_property	4
Retail Site | Westport, Connecticut
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Number of properties | office_and_property	2
Other Property | Stamford, Connecticut
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Area of real estate property (in square feet)	380,000

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Narrative (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Accounting Policies [Line Items]
Capitalized non-contingent leasing costs		$ 4,500
Minimum
Accounting Policies [Line Items]
Observatory revenue realized during the first quarter, previous ten years (as a percent)	16.00%
Observatory revenue realized during the second quarter, previous ten years (as a percent)	26.00%
Observatory revenue realized during the third quarter, previous ten years (as a percent)	31.00%
Observatory revenue realized during the fourth quarter, previous ten years (as a percent)	23.00%
Maximum
Accounting Policies [Line Items]
Observatory revenue realized during the first quarter, previous ten years (as a percent)	18.00%
Observatory revenue realized during the second quarter, previous ten years (as a percent)	28.00%
Observatory revenue realized during the third quarter, previous ten years (as a percent)	33.00%
Observatory revenue realized during the fourth quarter, previous ten years (as a percent)	25.00%
Ground lease agreements
Accounting Policies [Line Items]
Remaining contractual payments under ground lease agreements	$ 76,268

Deferred Costs, Acquired Leas_3

Deferred Costs, Acquired Lease Intangibles and Goodwill - Deferred Costs, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Leasing costs	$ 171,865	$ 164,751
Total deferred costs, gross amount	443,883	469,530
Less: accumulated amortization	(206,210)	(215,102)
Total deferred costs, net, excluding net deferred financing costs	237,673	254,428
Acquired in-place lease value and deferred leasing costs
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible assets	218,810	237,364
Acquired above-market leases
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible assets	$ 53,208	$ 67,415

Deferred Costs, Acquired Leas_4

Deferred Costs, Acquired Lease Intangibles and Goodwill - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Deferred Costs [Line Items]
Amortization expense related to deferred leasing costs	$ 6,300	$ 5,800	$ 18,400	$ 17,900
Revenue related to amortization of acquired above- and below-market leases, net	1,700	1,600	4,387	4,154
Goodwill	491,479		491,479		$ 491,479
Lease agreements
Deferred Costs [Line Items]
Amortization expense related to acquired lease intangibles	2,900	$ 4,000	9,300	$ 13,000
Observatory
Deferred Costs [Line Items]
Goodwill	227,500		227,500
Real estate
Deferred Costs [Line Items]
Goodwill	264,000		264,000
Revolving credit facility | Unsecured revolving credit facility
Deferred Costs [Line Items]
Net deferred financing costs	$ 6,800		$ 6,800		$ 8,300

Deferred Costs, Acquired Leas_5

Deferred Costs, Acquired Lease Intangibles and Goodwill - Amortizing Acquired Intangible Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Acquired below-market ground leases
Acquired below-market ground leases, gross	$ 396,916	$ 396,916
Less: accumulated amortization	(34,561)	(28,687)
Acquired below-market ground leases, net	362,355	368,229
Acquired below-market leases
Acquired below-market leases, gross	(120,568)	(132,026)
Less: accumulated amortization	64,906	65,979
Acquired below-market leases, net	$ (55,662)	$ (66,047)

Debt - Long-Term Debt (Details)

Debt - Long-Term Debt (Details) - USD ($)	9 Months Ended
	Sep. 30, 2018	Jan. 31, 2018	Dec. 31, 2017	Aug. 31, 2014
Debt Instrument [Line Items]
Unsecured facility	$ 0		$ 0
Deferred financing costs, net	(16,306,000)		(17,407,000)
Total	609,299,000		717,164,000
Mortgages
Debt Instrument [Line Items]
Fixed rate mortgage debt	615,537,000		721,224,000
Total principal	1,930,537,000		1,701,224,000
Unamortized discount, net of unamortized premium	(2,315,000)		(3,370,000)
Deferred financing costs, net	(9,538,000)		(9,133,000)
Total	1,918,684,000		1,688,721,000
Metro Center | Mortgages
Debt Instrument [Line Items]
Fixed rate mortgage debt	$ 92,372,000		93,948,000
Stated rate (as a percent)	3.59%
Effective Rate (as a percentage)	3.66%
10 Union Square | Mortgages
Debt Instrument [Line Items]
Fixed rate mortgage debt	$ 50,000,000		50,000,000
Stated rate (as a percent)	3.70%
Effective Rate (as a percentage)	3.97%
1542 Third Avenue | Mortgages
Debt Instrument [Line Items]
Fixed rate mortgage debt	$ 30,000,000		30,000,000
Stated rate (as a percent)	4.29%
Effective Rate (as a percentage)	4.53%
First Stamford Place | Mortgages
Debt Instrument [Line Items]
Fixed rate mortgage debt	$ 180,000,000		180,000,000
Stated rate (as a percent)	4.28%
Effective Rate (as a percentage)	4.44%
1010 Third Avenue and 77 West 55th Street | Mortgages
Debt Instrument [Line Items]
Fixed rate mortgage debt	$ 39,177,000		39,710,000
Stated rate (as a percent)	4.01%
Effective Rate (as a percentage)	4.20%
10 Bank Street | Mortgages
Debt Instrument [Line Items]
Fixed rate mortgage debt	$ 33,988,000		34,602,000
Stated rate (as a percent)	4.23%
Effective Rate (as a percentage)	4.35%
383 Main Avenue | Mortgages
Debt Instrument [Line Items]
Fixed rate mortgage debt	$ 30,000,000		30,000,000
Stated rate (as a percent)	4.44%
Effective Rate (as a percentage)	4.55%
1333 Broadway | Mortgages
Debt Instrument [Line Items]
Fixed rate mortgage debt	$ 160,000,000		66,602,000
Stated rate (as a percent)	4.21%	4.21%
Effective Rate (as a percentage)	4.26%
Face amount		$ 160,000,000
1400 Broadway (first lien mortgage loan) | Mortgages
Debt Instrument [Line Items]
Fixed rate mortgage debt	$ 0		66,632,000
Stated rate (as a percent)	0.00%
Effective Rate (as a percentage)	0.00%
1400 Broadway (second lien mortgage loan) | Mortgages
Debt Instrument [Line Items]
Fixed rate mortgage debt	$ 0		9,172,000
Stated rate (as a percent)	0.00%
Effective Rate (as a percentage)	0.00%
111 West 33rd Street (first lien mortgage loan) | Mortgages
Debt Instrument [Line Items]
Fixed rate mortgage debt	$ 0		74,045,000
Stated rate (as a percent)	0.00%
Effective Rate (as a percentage)	0.00%
111 West 33rd Street (second lien mortgage loan) | Mortgages
Debt Instrument [Line Items]
Fixed rate mortgage debt	$ 0		9,369,000
Stated rate (as a percent)	0.00%
Effective Rate (as a percentage)	0.00%
1350 Broadway | Mortgages
Debt Instrument [Line Items]
Fixed rate mortgage debt	$ 0		37,144,000
Stated rate (as a percent)	0.00%
Effective Rate (as a percentage)	0.00%
Senior unsecured notes - exchangeable | Convertible debt
Debt Instrument [Line Items]
Fixed rate mortgage debt	$ 250,000,000		250,000,000
Stated rate (as a percent)	2.625%			2.625%
Effective Rate (as a percentage)	3.93%
Face amount				$ 250,000,000
Senior unsecured notes, Series A | Senior notes
Debt Instrument [Line Items]
Total	$ 100,000,000		100,000,000
Stated rate (as a percent)	3.93%
Effective Rate (as a percentage)	3.96%
Senior unsecured notes, Series B | Senior notes
Debt Instrument [Line Items]
Total	$ 125,000,000		125,000,000
Stated rate (as a percent)	4.09%
Effective Rate (as a percentage)	4.12%
Senior unsecured notes, Series C | Senior notes
Debt Instrument [Line Items]
Total	$ 125,000,000		125,000,000
Stated rate (as a percent)	4.18%
Effective Rate (as a percentage)	4.21%
Senior unsecured notes, Series D | Senior notes
Debt Instrument [Line Items]
Total	$ 115,000,000		$ 115,000,000
Stated rate (as a percent)	4.08%		4.08%
Effective Rate (as a percentage)	4.11%
Face amount			$ 115,000,000
Senior unsecured notes, Series E | Senior notes
Debt Instrument [Line Items]
Total	$ 160,000,000		$ 0
Stated rate (as a percent)	4.26%		4.26%
Effective Rate (as a percentage)	4.27%
Face amount			$ 160,000,000
Senior unsecured notes, Series F | Senior notes
Debt Instrument [Line Items]
Total	$ 175,000,000		$ 0
Stated rate (as a percent)	4.44%		4.44%
Effective Rate (as a percentage)	4.45%
Face amount			$ 175,000,000
Unsecured revolving credit facility | Revolving credit facility
Debt Instrument [Line Items]
Unsecured facility	$ 0		0
Effective Rate (as a percentage)	3.36%
Unsecured revolving credit facility | Revolving credit facility | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percentage)	1.10%
Unsecured term loan facility | Revolving credit facility
Debt Instrument [Line Items]
Unsecured facility	$ 265,000,000		$ 265,000,000
Stated rate (as a percent)	3.35%
Pay rate (as a percent)	2.1485%
Unsecured term loan facility | Revolving credit facility | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percentage)	1.20%
First Stamford Place - First Lien | Mortgages
Debt Instrument [Line Items]
Stated rate (as a percent)	4.09%
Face amount	$ 164,000,000
First Stamford Place - Second Lien | Mortgages
Debt Instrument [Line Items]
Stated rate (as a percent)	6.25%
Face amount	$ 16,000,000

Debt - Mortgage Debt (Details)

Debt - Mortgage Debt (Details) - USD ($)	1 Months Ended	9 Months Ended
	Jan. 31, 2018	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Debt Instrument [Line Items]
Repayment of mortgage notes payable		$ 265,688,000	$ 344,618,000
Mortgages
Debt Instrument [Line Items]
Fixed rate mortgage debt		615,537,000		$ 721,224,000
1333 Broadway | Mortgages
Debt Instrument [Line Items]
Fixed rate mortgage debt		$ 160,000,000		$ 66,602,000
Face amount	$ 160,000,000
Stated rate (as a percent)	4.21%	4.21%
1400 Broadway | Mortgages
Debt Instrument [Line Items]
Repayment of mortgage notes payable	$ 75,800,000

Debt - Aggregate Required Princ

Debt - Aggregate Required Principal Payments (Details) - Mortgages - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Amortization
2018, amortization	$ 925
2019, amortization	3,790
2020, amortization	3,938
2021, amortization	4,090
2022, amortization	5,628
Thereafter	41,744
Total amortization	60,115
Maturities
2018, maturities	0
2019, maturities	250,000
2020, maturities	0
2021, maturities	0
2022, maturities	265,000
Thereafter	1,355,422
Total maturities	1,870,422
Total long term debt
2,018	925
2,019	253,790
2,020	3,938
2,021	4,090
2,022	270,628
Thereafter	1,397,166
Total	$ 1,930,537	$ 1,701,224

Debt - Deferred Financing Costs

Debt - Deferred Financing Costs, Net (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Debt Instrument [Line Items]
Financing costs	$ 25,312		$ 25,312		$ 24,446
Less: accumulated amortization	(9,006)		(9,006)		(7,039)
Total deferred financing costs, net	16,306		16,306		17,407
Amortization of deferred financing costs	1,100	$ 1,000	3,100	$ 3,600
Revolving credit facility | Unsecured revolving credit facility
Debt Instrument [Line Items]
Net deferred financing costs	$ 6,800		$ 6,800		$ 8,300

Debt - Unsecured Revolving Cred

Debt - Unsecured Revolving Credit and Term Loan Facility (Details) - Revolving Credit Facility	1 Months Ended
	Aug. 31, 2017USD ($)option
Unsecured Revolving Credit Facility and Term Loan
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 1,365,000,000
Unsecured revolving credit facility higher borrowing capacity option	1,750,000,000
Unsecured revolving credit facility
Line of Credit Facility [Line Items]
Current borrowing capacity	$ 1,100,000,000
Number of options to extend maturity | option	2
Extension period (in months)	6 months
Unsecured term loan facility
Line of Credit Facility [Line Items]
Current borrowing capacity	$ 265,000,000
Minimum | Unsecured revolving credit facility
Line of Credit Facility [Line Items]
Extension fee, as a percent of outstanding commitments under revolving credit facility (in percentage)	0.0625%
Maximum | Unsecured revolving credit facility
Line of Credit Facility [Line Items]
Extension fee, as a percent of outstanding commitments under revolving credit facility (in percentage)	0.075%

Debt - Exchangeable Senior Note

Debt - Exchangeable Senior Notes (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)$ / shares	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)$ / shares	Sep. 30, 2017USD ($)	Aug. 31, 2014USD ($)
Debt Instrument [Line Items]
Amortization of deferred financing costs	$ 1,100,000	$ 1,000,000	$ 3,100,000	$ 3,600,000
Convertible debt | Exchangeable Senior Notes due August 15, 2019
Debt Instrument [Line Items]
Face amount					$ 250,000,000
Stated rate (as a percent)	2.625%		2.625%		2.625%
Shares converted (ratio)			0.0519443
Conversion price (in USD per share) | $ / shares	$ 19.25		$ 19.25
Debt interest expense	$ 2,400,000	2,400,000	$ 7,300,000	7,300,000
Contractual interest expense	1,600,000	1,600,000	4,900,000	4,900,000
Accretion of debt discount	700,000	700,000	2,000,000	2,000,000
Amortization of deferred financing costs	$ 100,000	$ 100,000	$ 400,000	$ 400,000

Debt - Senior Unsecured Notes (

Debt - Senior Unsecured Notes (Details) - Senior notes - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Series D, Series E, and Series F Senior unsecured notes
Debt Instrument [Line Items]
Face amount		$ 450,000,000
Senior unsecured notes, Series D
Debt Instrument [Line Items]
Face amount		$ 115,000,000
Stated rate (as a percent)	4.08%	4.08%
Senior unsecured notes, Series E
Debt Instrument [Line Items]
Face amount		$ 160,000,000
Stated rate (as a percent)	4.26%	4.26%
Senior unsecured notes, Series F
Debt Instrument [Line Items]
Face amount		$ 175,000,000
Stated rate (as a percent)	4.44%	4.44%

Accounts Payable and Accrued _3

Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Payables and Accruals [Abstract]
Accrued capital expenditures	$ 92,506	$ 71,769
Accounts payable and accrued expenses	31,841	32,509
Interest rate swap agreements liability	0	436
Accrued interest payable	3,447	5,687
Due to affiliated companies	546	448
Total accounts payable and accrued expenses	$ 128,340	$ 110,849

Financial Instruments and Fai_3

Financial Instruments and Fair Values - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swap agreements liability	$ 0		$ 0		$ (436,000)
Loss from derivative financial instruments	0	$ 0	0	$ 289,000
Designated as Hedging Instrument | Cash Flow Hedging
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amount expected to be reclassified within twelve months			(2,300,000)
Deferred losses on terminated hedges	14,100,000		14,100,000		15,100,000
Loss expected to be reclassified within twelve months			1,500,000
Loss from derivative financial instruments				300,000
Notional amount, terminated		20,000,000		20,000,000
Designated as Hedging Instrument | Cash Flow Hedging | Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional amount	515,000,000		515,000,000		265,000,000
Other comprehensive income (loss)	4,300,000	$ (1,300,000)	11,400,000	$ (14,300,000)
Prepaid expenses and other assets | Designated as Hedging Instrument | Cash Flow Hedging | Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swap agreements asset	$ 9,900,000		$ 9,900,000
Accounts payable and accrued expenses | Designated as Hedging Instrument | Cash Flow Hedging | Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swap agreements liability					$ (400,000)

Financial Instruments and Fai_4

Financial Instruments and Fair Values - Summary of the Terms of Agreements and the Fair Value of Derivative Financial Instruments (Details) - Cash Flow Hedging - Designated as Hedging Instrument - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Asset	$ 9,944,000	$ 0
Liability	0	(436,000)
LIBOR | Interest Rate Swap, One Month LIBOR, 2.1485%
Derivatives, Fair Value [Line Items]
Notional Amount	$ 265,000,000
Pay Rate (as a percent)	2.1485%
Asset	$ 7,300,000	0
Liability	0	(436,000)
LIBOR | Interest Rate Swap, Three Month LIBOR, 2.9580%, Swap Number One [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	$ 125,000,000
Pay Rate (as a percent)	2.958%
Asset	$ 1,316,000	0
Liability	0	0
LIBOR | Interest Rate Swap, Three Month LIBOR, 2.9580%
Derivatives, Fair Value [Line Items]
Notional Amount	$ 125,000,000
Pay Rate (as a percent)	2.958%
Asset	$ 1,328,000	0
Liability	$ 0	$ 0

Financial Instruments and Fai_5

Financial Instruments and Fair Values - Effect of Derivative Financial Instruments Designated as Cash Flow Hedges (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in other comprehensive income (loss)	$ 3,884	$ (1,638)	$ 9,827	$ (14,654)
Amount of gain (loss) reclassified from accumulated other comprehensive income (loss) into interest expense	(427)	(359)	(1,562)	(402)
Interest expense	(20,658)	(16,890)	(58,774)	(52,109)
Interest Rate Swap
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in other comprehensive income (loss)	3,884	(1,638)	9,827	(14,654)
Amount of gain (loss) reclassified from accumulated other comprehensive income (loss) into interest expense	(427)	(359)	(1,562)	(402)
Accumulated net gain (loss) from cash flow hedges | Reclassification out of Accumulated Other Comprehensive Income | Interest Rate Swap
Derivative Instruments, Gain (Loss) [Line Items]
Interest expense	$ (427)	$ (359)	$ (1,562)	$ (402)

Financial Instruments and Fai_6

Financial Instruments and Fair Values - Summary of the Carrying and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swaps included in accounts payable and accrued expenses	$ 0	$ 436
Mortgages | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	609,299	717,164
Mortgages | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	574,238	707,300
Senior unsecured notes - exchangeable | Exchangeable notes | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	247,114	244,739
Senior unsecured notes - exchangeable | Exchangeable notes | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	251,563	275,723
Senior unsecured notes - Series A, B, C, D, E and F | Senior notes | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	798,248
Senior unsecured notes - Series A, B, C, D, E and F | Senior notes | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	773,375
Senior unsecured notes - Series A, B, C and D | Senior notes | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value		463,156
Senior unsecured notes - Series A, B, C and D | Senior notes | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value		460,352
Fair Value, Inputs, Level 1 | Mortgages | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Fair Value, Inputs, Level 1 | Senior unsecured notes - exchangeable | Exchangeable notes | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Fair Value, Inputs, Level 1 | Senior unsecured notes - Series A, B, C, D, E and F | Senior notes | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0
Fair Value, Inputs, Level 1 | Senior unsecured notes - Series A, B, C and D | Senior notes | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value		0
Fair Value, Inputs, Level 2 | Mortgages | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Fair Value, Inputs, Level 2 | Senior unsecured notes - exchangeable | Exchangeable notes | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	251,563	275,723
Fair Value, Inputs, Level 2 | Senior unsecured notes - Series A, B, C, D, E and F | Senior notes | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0
Fair Value, Inputs, Level 2 | Senior unsecured notes - Series A, B, C and D | Senior notes | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value		0
Fair Value, Inputs, Level 3 | Mortgages | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	574,238	707,300
Fair Value, Inputs, Level 3 | Senior unsecured notes - exchangeable | Exchangeable notes | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Fair Value, Inputs, Level 3 | Senior unsecured notes - Series A, B, C, D, E and F | Senior notes | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	773,375
Fair Value, Inputs, Level 3 | Senior unsecured notes - Series A, B, C and D | Senior notes | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value		460,352
Revolving Credit Facility | Unsecured term loan facility | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	264,023	263,662
Revolving Credit Facility | Unsecured term loan facility | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	265,000	265,000
Revolving Credit Facility | Fair Value, Inputs, Level 1 | Unsecured term loan facility | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Revolving Credit Facility | Fair Value, Inputs, Level 2 | Unsecured term loan facility | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Revolving Credit Facility | Fair Value, Inputs, Level 3 | Unsecured term loan facility | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	265,000	265,000
Interest Rate Swap | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swaps included in prepaid expenses and other assets	9,944	0
Interest rate swaps included in accounts payable and accrued expenses	0	436
Interest Rate Swap | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swaps included in prepaid expenses and other assets	9,944	0
Interest rate swaps included in accounts payable and accrued expenses	0	436
Interest Rate Swap | Fair Value, Inputs, Level 1 | Estimated Fair Value
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 Swap | Fair Value, Inputs, Level 2 | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swaps included in prepaid expenses and other assets	9,944	0
Interest rate swaps included in accounts payable and accrued expenses	0	436
Interest Rate Swap | Fair Value, Inputs, Level 3 | Estimated Fair Value
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 - Narrative (Deta

Rental Income - Narrative (Details)	Sep. 30, 2018
Minimum
Operating Leases [Line Items]
Term of lease	1 year
Maximum
Operating Leases [Line Items]
Term of lease	21 years

Commitments and Contingencies

Commitments and Contingencies - Legal Proceedings (Details)	1 Months Ended
	Oct. 31, 2014participant
New York State Supreme Court, New York County
Loss Contingencies [Line Items]
Number of plaintiffs opting out of settlement	12

Commitments and Contingencies_2

Commitments and Contingencies - Unfunded Capital Expenditures (Details) $ in Millions	Sep. 30, 2018USD ($)
Commitments and Contingencies Disclosure [Abstract]
Unfunded capital expenditures	$ 91.5

Commitments and Contingencies_3

Commitments and Contingencies - Aggregate Required Payments on Ground Leases (Details) - Ground leases $ in Thousands	Sep. 30, 2018USD ($)
Operating Leased Assets [Line Items]
2,018	$ 380
2,019	1,518
2,020	1,518
2,021	1,518
2,022	1,518
Thereafter	69,816
Aggregate required payments on ground leases	$ 76,268

Capital - Narrative (Details)

Capital - Narrative (Details)	9 Months Ended
	Sep. 30, 2018shares
Shares and Units [Abstract]
OP units outstanding (in shares)	303,333,599
OP units owned by the Company (in shares)	169,220,903
OP units owned by the Company (as a percent)	55.80%
OP units not owned by the Company (in shares)	134,112,696
OP units not owned by the Company (as a percent)	44.20%
Dividends on common stock received until performance criteria met for LTIP units (as a percent)	10.00%
Dividends on common stock received after performance criteria met for LTIP units (as a percent)	90.00%
Dividends on common stock received in periods after performance criteria met for LTIP units (as a percent)	100.00%

Capital - Distributions (Detail

Capital - Distributions (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Stockholders' Equity Note Disclosure, Disclosure of Compensation Related Costs, Share-based Payments and Earnings Per Share [Abstract]
Distributions paid to OP unitholders	$ 31.9	$ 31.5	$ 95.3	$ 94.5
Distributions paid to preferred unitholders	$ 0.2	$ 0.2	$ 0.7	$ 0.7

Capital - Incentive and Share-b

Capital - Incentive and Share-based Compensation (Details) $ / shares in Units, $ in Millions	1 Months Ended			3 Months Ended		9 Months Ended		12 Months Ended
	May 31, 2018USD ($)shares	Mar. 31, 2018USD ($)vesting_installmentshares	Feb. 28, 2018USD ($)vesting_installmentshares	Sep. 30, 2018USD ($)shares	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)$ / sharesshares	Sep. 30, 2017USD ($)	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility rate look-back period (in years)						6 years
Weighted-average per unit or share fair value (in USD per share) | $ / shares						$ 8.54
Age of grantee at which LTIP unit and restricted stock awards immediately vest						60 years
Period of service, upon completion of which, grantee's LTIP unit and restricted stock awards will immediately vest (in years)						10 years
Awards that meet age and service requirements for vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Noncash share-based compensation expense recognized | $				$ 0.4	$ 0.2	$ 1.7	$ 0.9
Unrecognized compensation expense | $				1.2		$ 1.2
Unrecognized compensation expense, period for recognition						2 years 2 months
Awards that do not meet age and service requirements for vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Noncash share-based compensation expense recognized | $				4.5	$ 3.7	$ 12.4	$ 9.9
Unrecognized compensation expense | $				$ 32		$ 32
Unrecognized compensation expense, period for recognition						2 years 3 months
Long-Term Incentive Plan Units 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
Weighted-average per unit or share fair value (in USD per share) | $ / shares						$ 8.54
Expected term						5 years 6 months 24 days
Dividend rate (as a percent)						2.30%
Risk free interest rate (as a percent)						2.50%
Expected volatility rate (as a percent)						17.00%
Time Based Long-Tern Incentive Plan Unit | 2013 Plan Units, granted in March 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares) | shares		67,449
Fair value of share-based awards granted in period | $		$ 1.7
Award vesting period		4 years
Number of vesting installments | vesting_installment		3
Performance Based Long-Term Incentive Plan Unit | 2013 Plan Units, granted in March 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares) | shares		223,950
Fair value of share-based awards granted in period | $		$ 1.1
Award vesting period		3 years
Number of vesting installments | vesting_installment		2
Time Restricted Shares | 2013 Plan Units, granted in March 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares) | shares		39,608
Executive Officer | Time Based Long-Tern Incentive Plan Unit | 2013 Plan Units, granted in March 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares) | shares		386,876
Fair value of share-based awards granted in period | $		$ 6.1
Executive Officer | Time Based Long-Tern Incentive Plan Unit | 2013 Plan Units, granted in February 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares) | shares			238,609
Fair value of share-based awards granted in period | $			$ 4
Award vesting period								3 years
Vesting percentage of award face amount								125.00%
Executive Officer | Time Based Long-Tern Incentive Plan Unit | Vesting immediately
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares) | shares			25,158
Executive Officer | Time Based Long-Tern Incentive Plan Unit | Vest ratably over three years
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares) | shares			213,451
Award vesting period			3 years
Executive Officer | Time Based Long-Tern Incentive Plan Unit | Vest in two equal annual installments
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of vesting installments | vesting_installment			2
Executive Officer | Performance Based Long-Term Incentive Plan Unit | 2013 Plan Units, granted in March 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares) | shares		1,737,917
Fair value of share-based awards granted in period | $		$ 9.6
Non-employee Director | Time Based Long-Tern Incentive Plan Unit | 2013 Plan Units, granted in February 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares) | shares	65,000
Fair value of share-based awards granted in period | $	$ 1
Non-employee Director | Time Based Long-Tern Incentive Plan Unit | Vest ratably over three years
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
2013 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized under the plan (in shares) | shares				12,200,000		12,200,000
Number of shares that remain available for future issuance (in shares) | shares				4,300,000		4,300,000

Capital - Summary of ESRT Restr

Capital - Summary of ESRT Restricted Stock and LTIP Unit Activity (Details)	9 Months Ended
	Sep. 30, 2018$ / sharesshares
Weighted Average Grant Fair Value [Roll Forward]
Beginning balance, Unvested, Weighted Average Grant Fair Value (in USD per share) | $ / shares	$ 11.20
Vested, Weighted Average Grant Fair Value (in USD per share) | $ / shares	14.58
Granted, Weighted Average Grant Fair Value (in USD per share) | $ / shares	8.54
Forfeited or unearned, Weighted Average Grant Fair Value (in USD per share) | $ / shares	8.52
Ending balance, Unvested, Weighted Average Grant Fair Value (in USD per share) | $ / shares	$ 9.68
Restricted Stock
Restricted Stock and LTIP Unit Activity [Roll Forward]
Beginning balance, Unvested (in shares)	90,791
Vested (in shares)	(30,693)
Granted (in shares)	39,608
Forfeited or unearned (in shares)	(7,811)
Ending balance, Unvested (in shares)	91,895
LTIP Units
Restricted Stock and LTIP Unit Activity [Roll Forward]
Beginning balance, Unvested (in shares)	3,588,609
Vested (in shares)	(492,877)
Granted (in shares)	2,719,801
Forfeited or unearned (in shares)	(103,490)
Ending balance, Unvested (in shares)	5,712,043

Capital - Earnings Per Unit (De

Capital - Earnings Per Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Numerator:
Net income	$ 29,230	$ 35,489	$ 77,472	$ 85,993
Private perpetual preferred unit distributions	(234)	(234)	(702)	(702)
Earnings allocated to unvested units	(212)	(228)	(586)	(582)
Net income attributable to common unitholders - basic and diluted	$ 28,784	$ 35,027	$ 76,184	$ 84,709
Denominator:
Weighted average units outstanding - basic (in units)	297,478,000	296,389,000	297,180,000	296,389,000
Effect of dilutive securities:
Effect of dilutive securities - stock-based compensation plans (in units)	0	762,000	1,000	848,000
Effect of dilutive securities - exchangeable senior notes (in units)	0	720,000	0	852,000
Weighted average units outstanding - diluted (in units)	297,478,000	297,871,000	297,181,000	298,089,000
Earnings per share:
Basic earnings (in USD per unit)	$ 0.10	$ 0.12	$ 0.26	$ 0.29
Diluted earnings (in USD per unit)	$ 0.10	$ 0.12	$ 0.26	$ 0.28
Antidilutive securities (in units)	541,947	954,533	458,698	840,092

Related Party Transactions - Na

Related Party Transactions - Narrative (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)ft²propertydirector	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)ft²propertydirector	Sep. 30, 2017USD ($)
Related Party Transaction [Line Items]
Area of real estate property (in square feet) | ft²	10,100,000		10,100,000
Number of directors | director	1		1
Affliliated entity | Supervisory fee revenue
Related Party Transaction [Line Items]
Revenue from related parties	$ 0.2	$ 0.3	$ 0.9	$ 0.9
Affliliated entity | Property management fee revenue
Related Party Transaction [Line Items]
Revenue from related parties	0.1	0.1	0.3	0.2
Affliliated entity | Leased space rental
Related Party Transaction [Line Items]
Revenue from related parties	$ 0.1	$ 0.1	$ 0.3	$ 0.3
Number of properties | property	1		1
Lease cancellation, notice period (in days)			90 days
Affliliated entity | Annualized rent revenue
Related Party Transaction [Line Items]
Revenue from related parties			$ 4.1
Undivided Interest
Related Party Transaction [Line Items]
Area of real estate property (in square feet) | ft²	5,351		5,351
Chairman emeritus | Leased space rental
Related Party Transaction [Line Items]
Percentage of lease space occupied by Chairman emeritus and employee			15.00%

Segment Reporting - Narrative

Segment Reporting - Narrative (Details)	9 Months Ended
	Sep. 30, 2018segment
Segment Reporting [Abstract]
Number of reportable segments	2

Segment Reporting - Components

Segment Reporting - Components of Segment Profit for Each Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Revenues:
Rental revenue	$ 123,621	$ 122,391	$ 369,970	$ 360,348
Intercompany rental revenue	0	0	0	0
Tenant expense reimbursement	18,627	20,346	52,626	53,889
Observatory revenue	40,241	39,306	96,691	94,212
Lease termination fees	1,185	1,165	2,164	10,354
Third-party management and other fees	312	345	1,151	1,088
Other revenue and fees	2,416	2,993	9,600	7,338
Revenues	186,402	186,546	532,202	527,229
Operating expenses:
Property operating expenses	42,772	41,270	126,375	122,009
Intercompany rent expense	0	0	0	0
Ground rent expenses	2,331	2,331	6,994	6,994
General and administrative expenses	13,148	12,899	39,001	36,566
Observatory expenses	8,854	8,648	23,868	23,079
Real estate taxes	28,284	26,901	81,771	76,001
Depreciation and amortization	42,475	38,490	121,826	119,868
Total operating expenses	137,864	130,539	399,835	384,517
Total operating income	48,538	56,007	132,367	142,712
Other income (expense):
Interest income	3,485	774	7,209	2,169
Interest expense	(20,658)	(16,890)	(58,774)	(52,109)
Loss on early extinguishment of debt	0	(2,157)	0	(2,157)
Loss from derivative financial instruments	0	0	0	(289)
Income before income taxes	31,365	37,734	80,802	90,326
Income tax expense	(2,135)	(2,245)	(3,330)	(4,333)
Net income	29,230	35,489	77,472	85,993
Segment assets	4,166,832	3,848,934	4,166,832	3,848,934	$ 3,931,347
Expenditures for segment assets	67,120	53,731	190,359	163,115
Intersegment Elimination
Revenues:
Rental revenue	0	0	0	0
Intercompany rental revenue	(23,805)	(23,301)	(59,356)	(57,354)
Tenant expense reimbursement	0	0	0	0
Observatory revenue	0	0	0	0
Lease termination fees	0	0	0	0
Third-party management and other fees	0	0	0	0
Other revenue and fees	0	0	0	0
Revenues	(23,805)	(23,301)	(59,356)	(57,354)
Operating expenses:
Property operating expenses	0	0	0	0
Intercompany rent expense	(23,805)	(23,301)	(59,356)	(57,354)
Ground rent expenses	0	0	0	0
General and administrative expenses	0	0	0	0
Observatory expenses	0	0	0	0
Real estate taxes	0	0	0	0
Depreciation and amortization	0	0	0	0
Total operating expenses	(23,805)	(23,301)	(59,356)	(57,354)
Total operating income	0	0	0	0
Other income (expense):
Interest income	0	0	0	0
Interest expense	0	0	0	0
Loss on early extinguishment of debt		0		0
Loss from derivative financial instruments				0
Income before income taxes	0	0	0	0
Income tax expense	0	0	0	0
Net income	0	0	0	0
Segment assets	0	0	0	0
Expenditures for segment assets	0	0	0	0
Real Estate | Operating Segments
Revenues:
Rental revenue	123,621	122,391	369,970	360,348
Intercompany rental revenue	23,805	23,301	59,356	57,354
Tenant expense reimbursement	18,627	20,346	52,626	53,889
Observatory revenue	0	0	0	0
Lease termination fees	1,185	1,165	2,164	10,354
Third-party management and other fees	312	345	1,151	1,088
Other revenue and fees	2,416	2,993	9,600	7,338
Revenues	169,966	170,541	494,867	490,371
Operating expenses:
Property operating expenses	42,772	41,270	126,375	122,009
Intercompany rent expense	0	0	0	0
Ground rent expenses	2,331	2,331	6,994	6,994
General and administrative expenses	13,148	12,899	39,001	36,566
Observatory expenses	0	0	0	0
Real estate taxes	28,284	26,901	81,771	76,001
Depreciation and amortization	42,458	38,473	121,775	119,764
Total operating expenses	128,993	121,874	375,916	361,334
Total operating income	40,973	48,667	118,951	129,037
Other income (expense):
Interest income	3,485	774	7,209	2,169
Interest expense	(20,658)	(16,890)	(58,774)	(52,109)
Loss on early extinguishment of debt		(2,157)		(2,157)
Loss from derivative financial instruments				(289)
Income before income taxes	23,800	30,394	67,386	76,651
Income tax expense	(277)	(264)	(852)	(960)
Net income	23,523	30,130	66,534	75,691
Segment assets	3,904,454	3,582,935	3,904,454	3,582,935
Expenditures for segment assets	52,613	40,320	148,429	142,854
Observatory | Operating Segments
Revenues:
Rental revenue	0	0	0	0
Intercompany rental revenue	0	0	0	0
Tenant expense reimbursement	0	0	0	0
Observatory revenue	40,241	39,306	96,691	94,212
Lease termination fees	0	0	0	0
Third-party management and other fees	0	0	0	0
Other revenue and fees	0	0	0	0
Revenues	40,241	39,306	96,691	94,212
Operating expenses:
Property operating expenses	0	0	0	0
Intercompany rent expense	23,805	23,301	59,356	57,354
Ground rent expenses	0	0	0	0
General and administrative expenses	0	0	0	0
Observatory expenses	8,854	8,648	23,868	23,079
Real estate taxes	0	0	0	0
Depreciation and amortization	17	17	51	104
Total operating expenses	32,676	31,966	83,275	80,537
Total operating income	7,565	7,340	13,416	13,675
Other income (expense):
Interest income	0	0	0	0
Interest expense	0	0	0	0
Loss on early extinguishment of debt		0		0
Loss from derivative financial instruments				0
Income before income taxes	7,565	7,340	13,416	13,675
Income tax expense	(1,858)	(1,981)	(2,478)	(3,373)
Net income	5,707	5,359	10,938	10,302
Segment assets	262,378	265,999	262,378	265,999
Expenditures for segment assets	$ 14,507	$ 13,411	$ 41,930	$ 20,261