Reckson Operating Partnership 10-K 23 Mar 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Mar. 22, 2018	Jun. 30, 2017
Document and Entity Information
Entity Registrant Name	RECKSON OPERATING PARTNERSHIP LP
Entity Central Index Key	930,810
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Public Float			$ 0
Entity Common Stock, Shares Outstanding		0
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands		Dec. 31, 2017	Dec. 31, 2016
Commercial real estate properties, at cost:
Land and land interests		$ 1,704,142	$ 1,805,198
Building and improvements		4,251,610	4,629,994
Building leasehold and improvements		1,073,703	1,073,678
Commercial real estate properties, gross		7,029,455	7,508,870
Less: accumulated depreciation		(1,492,603)	(1,437,222)
Total commercial real estate properties, net		5,536,852	6,071,648
Assets held for sale		67,228	0
Cash and cash equivalents		36,013	59,930
Restricted cash		41,117	43,489
Tenant and other receivables, net of allowance of $7,237 and $4,879 in 2017 and 2016, respectively		31,006	30,999
Deferred rents receivable, net of allowance of $11,189 and $17,798 in 2017 and 2016, respectively		233,300	238,447
Debt, preferred equity and other investments, net of discounts and deferred origination fees of $25,507 and $16,705 in 2017 and 2016, respectively		2,114,041	1,640,412
Investments in unconsolidated joint ventures		130,217	174,127
Deferred costs, net of accumulated amortization of $77,176 and $73,673 in 2017 and 2016, respectively		106,136	121,470
Other assets		245,598	374,091
Total assets(1)	[1]	8,541,508	8,754,613
Liabilities
Mortgages and other loans payable, net		829,648	676,068
Unsecured term loans, net		0	1,179,521
Unsecured notes, net		901,067	795,260
Accrued interest payable		14,999	15,781
Other liabilities		92,514	160,982
Accounts payable and accrued expenses		60,819	60,855
Related party payables		23,808	23,808
Deferred revenue		134,650	161,772
Deferred land leases payable		1,888	1,795
Dividends payable		807	754
Security deposits		39,085	40,033
Liabilities related to assets held for sale		42	0
Total liabilities	[1]	2,099,327	3,116,629
Commitments and contingencies
Preferred units		109,161	109,161
Capital
General partner capital		6,012,134	5,139,842
Limited partner capital		0	0
Accumulated other comprehensive loss		(1,259)	(1,618)
Total ROP partner's capital		6,010,875	5,138,224
Noncontrolling interests in other partnerships		322,145	390,599
Total capital		6,333,020	5,528,823
Total liabilities and capital		$ 8,541,508	$ 8,754,613
[1]	The Company's consolidated balance sheets include assets and liabilities of consolidated variable interest entities ("VIEs"). See Note 2. The consolidated balance sheets include the following amounts related to our consolidated VIEs: $268.6 million and $297.3 million of land, $1.3 billion and $1.4 billion of building and improvements, $319.1 million and $318.4 million of accumulated depreciation, $143.9 million and $160.5 million of other assets included in other line items, $495.0 million and $494.0 million of real estate debt, net, $2.1 million and $2.1 million of accrued interest payable, and $48.8 million and $61.4 million of other liabilities included in other line items as of December 31, 2017 and December 31, 2016, respectively.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Tenant and other receivables, net of allowance of $7,237 and $4,879 in 2017 and 2016, respectively	$ 7,237	$ 4,879
Deferred rents receivable, net of allowance of $11,189 and $17,798 in 2017 and 2016, respectively	11,189	17,798
Debt, preferred equity and other investments, net of discounts and deferred origination fees of $25,507 and $16,705 in 2017 and 2016, respectively	25,507	16,705
Deferred costs, net of accumulated amortization of $77,176 and $73,673 in 2017 and 2016, respectively	77,176	73,673
Commitments and contingencies
Land	1,704,142	1,805,198
Building and improvements	4,251,610	4,629,994
Accumulated depreciation	1,492,603	1,437,222
Other assets	245,598	374,091
Other liabilities	92,514	160,982
Variable Interest Entity, Primary Beneficiary
Land	268,600	297,300
Building and improvements	1,300,000	1,400,000
Accumulated depreciation	319,100	318,400
Other assets	100	160,500
Real estate debt, net	495,000	494,000
Interest payable	2,100	2,100
Other liabilities	$ 0	$ 61,400

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues
Rental revenue, net	$ 668,068	$ 652,629	$ 621,121
Escalation and reimbursement	99,887	104,683	95,894
Investment income	193,977	214,102	182,648
Other income	5,606	4,002	25,570
Total revenues	967,538	975,416	925,233
Expenses
Operating expenses, including $27,929 in 2017, $25,193 in 2016, and $26,728 in 2015 of related party expenses	164,219	166,137	163,969
Real estate taxes	156,967	152,010	143,873
Ground rent	20,941	20,971	20,941
Interest expense, net of interest income	123,969	109,208	119,342
Amortization of deferred financing costs	9,313	7,918	7,519
Depreciation and amortization	205,795	212,514	202,474
Transaction related costs	3	238	2,871
Marketing, general and administrative	496	720	464
Total expenses	681,703	669,716	661,453
Income before equity in net income from unconsolidated joint ventures, equity in net gain on sale of interest in unconsolidated joint venture, gain (loss) on sale of real estate, depreciable real estate reserves and loss on early extinguishment of debt	285,835	305,700	263,780
Equity in net income from unconsolidated joint ventures	14,192	14,509	8,841
Equity in net gain on sale of interest in unconsolidated joint venture	672	0	0
Gain (loss) on sale of real estate	69,826	(6,909)	100,190
Depreciable real estate reserves	(172,071)	0	(9,998)
Loss on early extinguishment of debt	0	0	(49)
Net income	198,454	313,300	362,764
Net loss (income) attributable to noncontrolling interests in other partnerships	17,440	(4,424)	(9,169)
Preferred units dividend	(3,819)	(3,821)	(1,698)
Net income attributable to ROP common unitholder	$ 212,075	$ 305,055	$ 351,897

Consolidated Statements of Ope5

Consolidated Statements of Operations (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Related party expenses included in operating expenses	$ 27,929	$ 25,193	$ 26,728

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income attributable to ROP common unitholder	$ 212,075	$ 305,055	$ 351,897
Other comprehensive income:
Change in net unrealized gain on derivative instruments	359	598	890
Comprehensive income attributable to ROP common unitholder	$ 212,434	$ 305,653	$ 352,787

Consolidated Statement of Capit

Consolidated Statement of Capital - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Increase (Decrease) in Partners' Capital
Beginning Balance	$ 5,528,823	$ 4,586,952	$ 5,080,081
Contributions	4,664,131	4,490,682	3,347,260
Distributions	(4,054,928)	(3,858,888)	(4,192,345)
Shares contributed by parent company			(10,000)
Net income	194,635	309,479	361,066
Other comprehensive income	359	598	890
Ending Balance	6,333,020	5,528,823	4,586,952
General Partner's Capital Class A Common Units | Class A Common Units
Increase (Decrease) in Partners' Capital
Beginning Balance	5,139,842	4,201,872	4,734,873
Contributions	4,664,031	4,490,682	3,315,582
Distributions	(4,003,814)	(3,857,767)	(4,190,480)
Shares contributed by parent company			(10,000)
Net income	212,075	305,055	351,897
Ending Balance	6,012,134	5,139,842	4,201,872
Limited Partner's Capital
Increase (Decrease) in Partners' Capital
Beginning Balance	0	0	0
Ending Balance	0	0	0
Noncontrolling Interests In Other Partnerships
Increase (Decrease) in Partners' Capital
Beginning Balance	390,599	387,296	348,314
Contributions	100	0	31,678
Distributions	(51,114)	(1,121)	(1,865)
Net income	(17,440)	4,424	9,169
Ending Balance	322,145	390,599	387,296
Accumulated Other Comprehensive (Loss) Income
Increase (Decrease) in Partners' Capital
Beginning Balance	(1,618)	(2,216)	(3,106)
Other comprehensive income	359	598	890
Ending Balance	$ (1,259)	$ (1,618)	$ (2,216)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Activities
Net income	$ 198,454	$ 313,300	$ 362,764
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	215,108	220,432	209,993
Equity in net gain on sale of interest in unconsolidated joint venture/real estate	(672)	0	0
Equity in net income from unconsolidated joint ventures	(14,192)	(14,509)	(8,841)
Distributions of cumulative earnings from unconsolidated joint ventures	14,613	10,430	8,621
Loss on early extinguishment of debt	0	0	49
Depreciable real estate reserve	172,071	0	9,998
(Gain) loss on sale of real estate, net	(69,826)	6,909	(100,190)
Deferred rents receivable	(6,762)	(23,768)	(21,378)
Other non-cash adjustments	(46,015)	(46,449)	(64,329)
Changes in operating assets and liabilities:
Restricted cash—operations	2,225	(11,585)	(1,182)
Tenant and other receivables	(3,139)	1,511	(9,900)
Deferred lease costs	(13,005)	(27,625)	(38,623)
Other assets	(11,431)	12,872	14,558
Accounts payable, accrued expenses, other liabilities, and security deposits	(5,722)	(2,937)	2,458
Deferred revenue and land leases payable	(1,385)	1,684	1,487
Net cash provided by operating activities	430,322	440,265	365,485
Investing Activities
Acquisitions of real estate property	(228)	0	(109,633)
Additions to land, buildings and improvements	(120,018)	(127,200)	(89,998)
Escrowed cash—capital improvements/acquisition deposits	0	772	593
Investments in unconsolidated joint venture	(488)	(25,373)	(988)
Distributions in excess of cumulative earnings from unconsolidated joint ventures	49,270	1,304	28,459
Net proceeds from disposition of real estate/joint venture interest	343,842	42,316	238,083
Other investments	57,655	14,292	(54,475)
Origination of debt and preferred equity investments	(1,129,493)	(977,699)	(758,133)
Repayments or redemption of preferred equity investments	782,914	904,517	520,218
Net cash used in investing activities	(16,546)	(167,071)	(225,874)
Financing Activities
Proceeds from mortgages and other loans payable	340,809	50,383	360,018
Repayments of mortgages and other loans payable	(184,642)	(119,165)	(326,594)
Proceeds from revolving credit facility, term loan and senior unsecured notes	1,898,134	1,325,300	2,515,000
Repayments of revolving credit facility term loan and senior unsecured notes	(1,792,971)	(2,324,608)	(1,706,007)
Contributions from common unitholder	3,348,730	4,490,682	3,201,654
Contributions from noncontrolling interests in other partnerships	100	0	9,400
Distributions to noncontrolling interests in other partnerships	(51,114)	(1,121)	(1,865)
Distributions to common and preferred unitholder	(4,007,580)	(3,738,853)	(4,191,371)
Deferred loan costs and capitalized lease obligation	(5,520)	(5,058)	(9,511)
Other obligation related to mortgage loan participation	16,361	59,150	25,000
Net cash used in provided by financing activities	(437,693)	(263,290)	(124,276)
Net (decrease) increase in cash and cash equivalents	(23,917)	9,904	15,335
Cash and cash equivalents at beginning of year	59,930	50,026	34,691
Cash and cash equivalents at end of year	36,013	59,930	50,026
Supplemental Cash Flow Disclosure:
Interest paid	125,289	110,656	118,090
Supplemental Disclosure of Non-Cash Investing and Financing Activities:
Tenant improvements and capital expenditures payable	2,018	4,029	3,441
Deferred leasing payable	733	4,072	7,752
Change in fair value of hedge	165	206	570
Transfer of assets to assets held for sale	340,683	0	0
Transfer of liabilities related to assets held for sale	1,332	0	0
Contributions from common unitholder	1,315,301	0	13,928
Distribution of land to common unitholder	0	8,980	0
Deconsolidation of a subsidiary	3,520	0	27,435
Issuance of SL Green common stock to a consolidated joint venture	0	0	10,000
Contribution of notes receivable from the common unit holder	0	0	90,000
Issuance of preferred units through a subsidiary	0	0	109,161
Contributions from a noncontrolling interest in other partnerships	0	0	22,278
Exchange of debt investment for equity in joint venture	0	68,581	0
Removal of fully depreciated commercial real estate properties	0	12,326	0
Settlement of related party receivable with SL Green common stock	0	90,000	0
Issuance of related party payable for SL Green common stock	$ 0	$ 23,808	$ 0

Organization and Basis of Prese

Organization and Basis of Presentation	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	Organization and Basis of Presentation Reckson Operating Partnership, L.P., or ROP, commenced operations on June 2, 1995. The sole general partner of ROP is Wyoming Acquisition GP LLC., or WAGP, a wholly-owned subsidiary of SL Green Operating Partnership, L.P., or the Operating Partnership. The sole limited partner of ROP is the Operating Partnership. The Operating Partnership is 95.42% owned by SL Green Realty Corp., or SL Green, as of December 31, 2017 . SL Green is a self-administered and self-managed real estate investment trust, and is the sole managing general partner of the Operating Partnership. Unless the context requires otherwise, all references to "we," "our," "us" and the "Company" means ROP and all entities owned or controlled by ROP. We are engaged in the acquisition, ownership, management and operation of commercial and residential real estate properties, principally office properties, and also own land for future development, in the New York metropolitan area. SL Green and the Operating Partnership were formed in June 1997. SL Green has qualified, and expects to qualify in the current fiscal year, as a real estate investment trust, or REIT, under the Internal Revenue Code of 1986, as amended, or the Code, and operates as a self-administered, self-managed REIT. A REIT is a legal entity that holds real estate interests and, through payments of dividends to stockholders, is permitted to minimize the payment of Federal income taxes at the corporate level. On January 25, 2007, SL Green completed the acquisition of all of the outstanding shares of common stock of Reckson Associates Realty Corp., or RARC, our prior general partner. This transaction is referred to herein as the Merger. In 2015, SL Green transferred two properties and SL Green's tenancy in common interest in a fee interest with a total value of $395.0 million to us. Additionally, in 2015, SL Green transferred one entity that held debt investments and financing receivables with an aggregate carrying value of $1.7 billion to us. These transfers were made to further diversify our portfolio. Under the business combinations guidance (Accounting Standard Codification, or ASC, 805-50), these transfers were determined to be transfers of businesses between the indirect parent company and its wholly-owned subsidiary. As such, the assets and liabilities of the properties were transferred at their carrying values and were recorded as of the beginning of the current reporting period as though the assets and liabilities had been transferred at that date. The consolidated financial statements and financial information presented for all prior periods have been retrospectively adjusted to furnish comparative information. As of December 31, 2017 , we owned the following interests in properties in the New York metropolitan area, primarily in midtown Manhattan. Our investments located outside of Manhattan are referred to as the Suburban properties: Location Type Number of Properties Approximate Square Feet (unaudited) Weighted Average (1) (unaudited) Commercial: Manhattan Office 16 8,463,245 95.9 % Retail (2)(3) 5 364,816 98.0 % Fee Interest 1 176,530 100.0 % 22 9,004,591 96.0 % Suburban Office (4) 13 2,150,400 85.5 % Retail 1 52,000 100.0 % 14 2,202,400 85.9 % Total commercial properties 36 11,206,991 94.0 % Residential: Manhattan Residential (2) — 222,855 85.9 % Total portfolio 36 11,429,846 93.9 % ____________________________________________________________________ (1) The weighted average occupancy for commercial properties represents the total occupied square feet divided by total square footage at acquisition. The weighted average occupancy for residential properties represents the total occupied units divided by total available units. (2) As of December 31, 2017 , we owned a building that was comprised of approximately 270,132 square feet (unaudited) of retail space and approximately 222,855 square feet (unaudited) of residential space. For the purpose of this report, we have included the building in the number of retail properties we own. However, we have included only the retail square footage in the retail approximate square footage, and have listed the balance of the square footage as residential square footage. (3) Includes two unconsolidated joint venture retail properties at 131-137 Spring Street comprised of approximately 68,342 square feet (unaudited). (4) Includes the properties at 115-117 Stevens Avenue in Valhalla, New York, and 1-6 International Drive in Rye Brook, New York which were classified as held for sale at December 31, 2017. As of December 31, 2017 , we also held debt and preferred equity investments with a book value of $2.2 billion , including $0.1 billion of debt and preferred equity investments and other financing receivables that are included in balance sheet line items other than the Debt and Preferred Equity Investments line item.

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies Principles of Consolidation The consolidated financial statements include our accounts and those of our subsidiaries, which are wholly-owned or controlled by us. Entities which we do not control through our voting interest and entities which are variable interest entities, but where we are not the primary beneficiary, are accounted for under the equity method. See Note 5, "Debt and Preferred Equity Investments" and Note 6, "Investments in Unconsolidated Joint Ventures." All significant intercompany balances and transactions have been eliminated. We consolidate a variable interest entity, or VIE, in which we are considered the primary beneficiary. The primary beneficiary 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. A noncontrolling interest in a consolidated subsidiary is defined as the portion of the equity (net assets) in a subsidiary not attributable, directly or indirectly, to us. Noncontrolling interests are required to be presented as a separate component of equity in the consolidated balance sheet and the presentation of net income is modified to present earnings and other comprehensive income attributed to controlling and noncontrolling interests. We assess the accounting treatment for each joint venture and debt and preferred equity investment. This assessment includes a review of each joint venture or limited liability company agreement to determine the rights provided to each party and whether those rights are protective or participating. For all VIEs, we 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. In situations where we and our partner approve, among other things, the annual budget, receive a detailed monthly reporting package, meet on a quarterly basis to review the results of the joint venture, review and approve the joint venture's tax return before filing, and approve all leases that cover more than a nominal amount of space relative to the total rentable space at each property, we do not consolidate the joint venture as we consider these to be substantive participation rights that result in shared power of the activities that most significantly impact the performance of the joint venture. Our joint venture agreements typically contain certain protective rights such as requiring partner approval to sell, finance or refinance the property and the payment of capital expenditures and operating expenditures outside of the approved budget or operating plan. In January 2018, the partnership agreement for our investment in the property at 919 Third Avenue was modified resulting in our partner now having substantive participating rights in the venture. As a result the investment will no longer be deemed a VIE and our investment in the property will be deconsolidated as of January 1, 2018. The Company will record its non-controlling interest at fair value. This fair value will be allocated to the assets and liabilities, including identified intangibles. Under this methodology, the leases are ascribed an in-place lease intangible value as well as an above or below market lease intangible value which will be amortized over the remaining term of the associated leases. Investment in Commercial Real Estate Properties Real estate properties are presented at cost less accumulated depreciation and amortization. Costs directly related to the development or redevelopment of properties are capitalized. Ordinary repairs and maintenance are expensed as incurred; major replacements and betterments, which improve or extend the life of the asset, are capitalized and depreciated over their estimated useful lives. We recognize the assets acquired, liabilities assumed (including contingencies) and any noncontrolling interests in an acquired entity at their respective fair values on the acquisition date. When we acquire our partner's equity interest in an existing unconsolidated joint venture and gain control over the investment, we record the consolidated investment at fair value. The difference between the book value of our equity investment on the purchase date and our share of the fair value of the investment's purchase price is recorded as a purchase price fair value adjustment in our consolidated statements of operations. See Note 3, "Property Acquisitions." We allocate the purchase price of real estate to land and building (inclusive of tenant improvements) and, if determined to be material, intangibles, such as the value of above- and below-market leases and origination costs associated with the in-place leases. We depreciate the amount allocated to building (inclusive of tenant improvements) over their estimated useful lives, which generally range from three to 40 years . We amortize the amount allocated to the above- and below-market leases over the remaining term of the associated lease, which generally range from one to 14 years , and record it as either an increase (in the case of below-market leases) or a decrease (in the case of above-market leases) to rental income. We amortize the amount allocated to the values associated with in-place leases over the expected term of the associated lease, which generally ranges from one to 14 years . If a tenant vacates its space prior to the contractual termination of the lease and no rental payments are being made on the lease, any unamortized balance of the related intangible will be written off. The tenant improvements and origination costs are amortized as an expense over the remaining life of the lease (or charged against earnings if the lease is terminated prior to its contractual expiration date). We assess fair value of the leases based on estimated cash flow projections that utilize appropriate discount and capitalization rates and available market information. Estimates of future cash flows are based on a number of factors including the historical operating results, known trends, and market/economic conditions that may affect the property. To the extent acquired leases contain fixed rate renewal options that are below-market and determined to be material, we amortize such below-market lease value into rental income over the renewal period. As of December 31, 2017 , the weighted average amortization period for above-market leases, below-market leases, and in-place lease costs is 4.4 years, 24.4 years, and 18.1 years, respectively. We incur a variety of costs in the development and leasing of our properties. After the determination is made to capitalize a cost, it is allocated to the specific component of a project that is benefited. Determination of when a development project is substantially complete and capitalization must cease involves a degree of judgment. The costs of land and building under development include specifically identifiable costs. The capitalized costs include, but are not limited to, pre-construction costs essential to the development of the property, development costs, construction costs, interest costs, real estate taxes, salaries and related costs and other costs incurred during the period of development. We consider a construction project as substantially completed and held available for occupancy upon the completion of tenant improvements, but no later than one year after major construction activity ceases. We cease capitalization on the portions substantially completed and occupied or held available for occupancy, and capitalize only those costs associated with the portions under construction. Properties are depreciated using the straight-line method over the estimated useful lives of the assets. The estimated useful lives are as follows: Category Term Building (fee ownership) 40 years Building improvements shorter of remaining life of the building or useful life Building (leasehold interest) lesser of 40 years or remaining term of the lease Property under capital lease remaining lease term Furniture and fixtures four to seven years Tenant improvements shorter of remaining term of the lease or useful life Depreciation expense (including amortization of capital lease assets) totaled $188.9 million , $196.2 million , and $187.2 million and for the years ended December 31, 2017 , 2016 and 2015 , respectively. On a periodic basis, we assess whether there are any indications that the value of our real estate properties may be other than temporarily impaired or that their carrying value may not be recoverable. A property's value is considered impaired if management's estimate of the aggregate future cash flows (undiscounted) to be generated by the property is less than the carrying value of the property. To the extent impairment has occurred, the loss will be measured as the excess of the carrying amount of the property over the calculated fair value of the property. We also evaluate our real estate properties for impairment when a property has been classified as held for sale. Real estate assets held for sale are valued at the lower of their carrying value or fair value less costs to sell and depreciation expense is no longer recorded. See Note 4, "Properties Held for Sale and Dispositions." Cash and Cash Equivalents We consider all highly liquid investments with maturity of three months or less when purchased to be cash equivalents. Restricted Cash Restricted cash primarily consists of security deposits held on behalf of our tenants, interest reserves, as well as capital improvement and real estate tax escrows required under certain loan agreements. Fair Value Measurements See Note 11, "Fair Value Measurements." Investments in Unconsolidated Joint Ventures We account for our investments in unconsolidated joint ventures under the equity method of accounting in cases where we exercise significant influence over, but do not control, these entities and are not considered to be the primary beneficiary. We consolidate those joint ventures that we control or which are VIEs and where we are considered to be the primary beneficiary. In all these joint ventures, the rights of the joint venture partner are both protective as well as participating. Unless we are determined to be the primary beneficiary in a VIE, these participating rights preclude us from consolidating these VIE entities. These investments are recorded initially at cost, as investments in unconsolidated joint ventures, and subsequently adjusted for equity in net income (loss) and cash contributions and distributions. Equity in net income (loss) from unconsolidated joint ventures is allocated based on our ownership or economic interest in each joint venture. When a capital event (as defined in each joint venture agreement) such as a refinancing occurs, if return thresholds are met, future equity income will be allocated at our increased economic interest. We recognize incentive income from unconsolidated real estate joint ventures as income to the extent it is earned and not subject to a clawback feature. Distributions we receive from unconsolidated real estate joint ventures in excess of our basis in the investment are recorded as offsets to our investment balance if we remain liable for future obligations of the joint venture or may otherwise be committed to provide future additional financial support. None of the joint venture debt is recourse to us. See Note 6, "Investments in Unconsolidated Joint Ventures." We assess our investments in unconsolidated joint ventures for recoverability, and if it is determined that a loss in value of the investment is other than temporary, we write down the investment to its fair value. We evaluate our equity investments for impairment based on the joint ventures' projected discounted cash flows. We do not believe that the values of any of our equity investments were impaired at December 31, 2017 . We may originate loans for real estate acquisition, development and construction, where we expect to receive some of the residual profit from such projects. When the risk and rewards of these arrangements are essentially the same as an investor or joint venture partner, we account for these arrangements as real estate investments under the equity method of accounting for investments. Otherwise, we account for these arrangements consistent with the accounting for our debt and preferred equity investments. Deferred Lease Costs Deferred lease costs consist of fees and direct costs incurred to execute operating leases and are amortized on a straight-line basis over the related lease term. Deferred Financing Costs Deferred financing costs represent commitment fees, legal, title and other third party costs associated with obtaining commitments for financing which result in a closing of such financing. These costs are amortized over the terms of the respective agreements. Unamortized deferred financing costs are expensed when the associated debt is refinanced or repaid before maturity. Costs incurred in seeking financing transactions, which do not close, are expensed in the period in which it is determined that the financing will not close. Deferred debt issuance costs related to a recognized debt liability are presented in the balance sheet as a direct deduction from the carrying amount of that debt liability. Revenue Recognition Rental revenue is recognized on a straight-line basis over the term of the lease. Rental revenue recognition commences when the tenant takes possession or controls the physical use of the leased space. In order for the tenant to take possession, the leased space must be substantially ready for its intended use. To determine whether the leased space is substantially ready for its intended use, management evaluates whether we are or the tenant is the owner of tenant improvements for accounting purposes. When management concludes that we are the owner of tenant improvements, rental revenue recognition begins when the tenant takes possession of the finished space, which is when such tenant improvements are substantially complete. In certain instances, when management concludes that we are not the owner (the tenant is the owner) of tenant improvements, rental revenue recognition begins when the tenant takes possession of or controls the space. When management concludes that we are the owner of tenant improvements for accounting purposes, we record amounts funded to construct the tenant improvements as a capital asset. For these tenant improvements, we record amounts reimbursed by tenants as a reduction of the capital asset. When management concludes that the tenant is the owner of tenant improvements for accounting purposes, we record our contribution towards those improvements as a lease incentive, which is included in deferred costs, net on our consolidated balance sheets and amortized as a reduction to rental revenue on a straight-line basis over the term of the lease. The excess of rents recognized over amounts contractually due pursuant to the underlying leases are included in deferred rents receivable on the consolidated balance sheets. We establish, on a current basis, an allowance for future potential tenant credit losses, which may occur against this account. The balance reflected on the consolidated balance sheets is net of such allowance. In addition to base rent, our tenants also generally will pay their pro rata share of increases in real estate taxes and operating expenses for the building over a base year. In some leases, in lieu of paying additional rent based upon increases in building operating expenses, the tenant will pay additional rent based upon increases in the wage rate paid to porters over the porters' wage rate in effect during a base year or increases in the consumer price index over the index value in effect during a base year. In addition, many of our leases contain fixed percentage increases over the base rent to cover escalations. Electricity is most often supplied by the landlord either on a sub-metered basis, or rent inclusion basis (i.e., a fixed fee is included in the rent for electricity, which amount may increase based upon increases in electricity rates or increases in electrical usage by the tenant). Base building services other than electricity (such as heat, air conditioning and freight elevator service during business hours, and base building cleaning) are typically provided at no additional cost, with the tenant paying additional rent only for services which exceed base building services or for services which are provided outside normal business hours. These escalations are based on actual expenses incurred in the prior calendar year. If the expenses in the current year are different from those in the prior year, then during the current year, the escalations will be adjusted to reflect the actual expenses for the current year. We recognized $17.0 million , $20.2 million , and $24.9 million of rental revenue for the years ended December 31, 2017 , 2016 , and 2015 , respectively, for the amortization of aggregate below-market leases in excess of above-market leases and a reduction in lease origination costs, resulting from the allocation of the purchase price of the applicable properties. We recognized as an increase (a reduction) to interest expense the amortization of the above-market rate mortgages assumed of $0.0 million , $0.1 million , and $0.4 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. The following summarizes our identified intangible assets (acquired above-market leases and in-place leases) and intangible liabilities (acquired below-market leases) as of December 31, 2017 and 2016 (in thousands): December 31, 2017 December 31, 2016 Identified intangible assets (included in other assets): Gross amount $ 276,163 $ 311,830 Accumulated amortization (236,737 ) (253,064 ) Net (1) $ 39,426 $ 58,766 Identified intangible liabilities (included in deferred revenue): Gross amount $ 496,438 $ 524,793 Accumulated amortization (366,091 ) (368,738 ) Net (1) $ 130,347 $ 156,055 (1) As of December 31, 2017, 0.1 million net intangible assets and 0.1 million net intangible liabilities were reclassified to assets held for sale and liabilities related to assets held for sale. The estimated annual amortization of acquired above-market leases, net of acquired (below-market) leases (a component of rental revenue), for each of the five succeeding years is as follows (in thousands): 2018 $ (13,620 ) 2019 (13,117 ) 2020 (12,301 ) 2021 (3,815 ) 2022 (3,512 ) The estimated annual amortization of all other identifiable assets (a component of depreciation and amortization expense) including tenant improvements for each of the five succeeding years is as follows (in thousands): 2018 $ 8,188 2019 6,641 2020 5,830 2021 2,985 2022 1,423 We record a gain on sale of real estate when title is conveyed to the buyer, subject to the buyer's financial commitment being sufficient to provide economic substance to the sale and provided that we have no substantial economic involvement with the buyer. Interest income on debt and preferred equity investments is accrued based on the contractual terms of the instruments and when, in the opinion of management, it is deemed collectible. Some debt and preferred equity investments provide for accrual of interest at specified rates, which differ from current payment terms. Interest is recognized on such loans at the accrual rate subject to management's determination that accrued interest is ultimately collectible, based on the underlying collateral and operations of the borrower. If management cannot make this determination, interest income above the current pay rate is recognized only upon actual receipt. Deferred origination fees, original issue discounts and loan origination costs, if any, are recognized as an adjustment to interest income over the terms of the related investments using the effective interest method. Fees received in connection with loan commitments are also deferred until the loan is funded and are then recognized over the term of the loan as an adjustment to yield. Discounts or premiums associated with the purchase of loans are amortized or accreted into interest income as a yield adjustment on the effective interest method based on expected cash flows through the expected maturity date of the related investment. If we purchase a debt or preferred equity investment at a discount, intend to hold it until maturity and expect to recover the full value of the investment, we accrete the discount into income as an adjustment to yield over the term of the investment. If we purchase a debt or preferred equity investment at a discount with the intention of foreclosing on the collateral, we do not accrete the discount. For debt investments acquired at a discount for credit quality, the difference between contractual cash flows and expected cash flows at acquisition is not accreted. Anticipated exit fees, the collection of which is expected, are also recognized over the term of the loan as an adjustment to yield. Debt and preferred equity investments are placed on a non-accrual status at the earlier of the date at which payments become 90 days past due or when, in the opinion of management, a full recovery of interest income becomes doubtful. Interest income recognition on any non-accrual debt or preferred equity investment is resumed when such non-accrual debt or preferred equity investment becomes contractually current and performance is demonstrated to be resumed. Interest is recorded as income on impaired loans only to the extent cash is received. We may syndicate a portion of the loans that we originate or sell the loans individually. When a transaction meets the criteria for sale accounting, we derecognize the loan sold and recognize gain or loss based on the difference between the sales price and the carrying value of the loan sold. Any related unamortized deferred origination fees, original issue discounts, loan origination costs, discounts or premiums at the time of sale are recognized as an adjustment to the gain or loss on sale, which is included in investment income on the consolidated statement of operations. Any fees received at the time of sale or syndication are recognized as part of investment income. Asset management fees are recognized on a straight-line basis over the term of the asset management agreement. Allowance for Doubtful Accounts We maintain an allowance for doubtful accounts for estimated losses resulting from the inability of our tenants to make required payments. If the financial condition of a specific tenant were to deteriorate, resulting in an impairment of its ability to make payments, additional allowances may be required. Reserve for Possible Credit Losses The expense for possible credit losses in connection with debt and preferred equity investments is the charge to earnings to increase the allowance for possible credit losses to the level that we estimate to be adequate, based on Level 3 data, considering delinquencies, loss experience and collateral quality. Other factors considered include geographic trends, product diversification, the size of the portfolio and current economic conditions. Based upon these factors, we establish a provision for possible credit loss on each individual investment. When it is probable that we will be unable to collect all amounts contractually due, the investment is considered impaired. Where impairment is indicated on an investment that is held to maturity, a valuation allowance is measured based upon the excess of the recorded investment amount over the fair value of the collateral. Any deficiency between the carrying amount of an asset and the calculated value of the collateral is charged to expense. We continue to assess or adjust our estimates based on circumstances of a loan and the underlying collateral. If additional information reflects increased recovery of our investment, we will adjust our reserves accordingly. There were no loan reserves recorded during the years ended December 31, 2017 , 2016 , and 2015 . Debt and preferred equity investments held for sale are carried at the lower of cost or fair market value using available market information obtained through consultation with dealers or other originators of such investments as well as discounted cash flow models based on Level 3 data pursuant to ASC 820-10. As circumstances change, management may conclude not to sell an investment designated as held for sale. In such situations, the investment will be reclassified at its net carrying value to debt and preferred equity investments held to maturity. For these reclassified investments, the difference between the current carrying value and the expected cash to be collected at maturity will be accreted into income over the remaining term of the investment. Rent Expense Rent expense is recognized on a straight-line basis over the initial term of the lease. The excess of the rent expense recognized over the amounts contractually due pursuant to the underlying lease is included in the deferred lease payable on the consolidated balance sheets. Exchangeable Debt Instruments The initial proceeds from exchangeable debt that may be settled in cash, including partial cash settlements, are bifurcated between a liability component and an equity component associated with the embedded conversion option. The objective of the accounting guidance is to require the liability and equity components of exchangeable debt to be separately accounted for in a manner such that the interest expense on the exchangeable debt is not recorded at the stated rate of interest but rather at an effective rate that reflects the issuer's conventional debt borrowing rate at the date of issuance. We calculate the liability component of exchangeable debt based on the present value of the contractual cash flows discounted at our comparable market conventional debt borrowing rate at the date of issuance. The difference between the principal amount and the fair value of the liability component is reported as a discount on the exchangeable debt that is accreted as additional interest expense from the issuance date through the contractual maturity date using the effective interest method. A portion of this additional interest expense may be capitalized to the development and redevelopment balances qualifying for interest capitalization each period. The liability component of the exchangeable debt is reported net of discounts on our consolidated balance sheets. We calculate the equity component of exchangeable debt based on the difference between the initial proceeds received from the issuance of the exchangeable debt and the fair value of the liability component at the issuance date. The equity component is included in additional paid-in-capital, net of issuance costs, on our consolidated balance sheets. We allocate issuance costs for exchangeable debt between the liability and the equity components based on their relative values. Income Taxes SL Green is taxed as a REIT under Section 856(c) of the Code. As a REIT, SL Green generally is not subject to Federal income tax. To maintain its qualification as a REIT, SL Green must distribute at least 90% of its REIT taxable income to its stockholders and meet certain other requirements. If SL Green fails to qualify as a REIT in any taxable year, SL Green will be subject to Federal income tax on its taxable income at regular corporate rates. SL Green may also be subject to certain state, local and franchise taxes. Under certain circumstances, Federal income and excise taxes may be due on its undistributed taxable income. ROP is a disregarded entity of SL Green Operating Partnership, L.P. for federal income tax purposes, and, as a result, all income and losses of ROP are considered income and losses of SL Green Operating Partnership, L. P. No provision has been made for income taxes in the consolidated financial statements since such taxes, if any, are the responsibility of the individual partners of SL Green Operating Partnership, L.P. We follow a two-step approach for evaluating uncertain tax positions. Recognition (step one) occurs when an enterprise concludes that a tax position, based solely on its technical merits, is more-likely-than-not to be sustained upon examination. Measurement (step two) determines the amount of benefit that is more-likely-than-not to be realized upon settlement. Derecognition of a tax position that was previously recognized would occur when a company subsequently determines that a tax position no longer meets the more-likely-than-not threshold of being sustained. The use of a valuation allowance as a substitute for derecognition of tax positions is prohibited. On December 22, 2017, the Tax Cuts and Jobs Act (the ‘‘Tax Act’’) was signed into law and makes substantial changes to the Code. Many of the provisions of the Tax Act will require guidance through the issuance of Treasury regulations in order to assess their effect. The Tax Act did not have a material impact on our financial statements for the year ended December, 31, 2017. Derivative Instruments In the normal course of business, we use a variety of commonly used derivative instruments, such as interest rate swaps, caps, collars and floors, to manage, or hedge, interest rate risk. Effectiveness is essential for those derivatives that we intend to qualify for hedge accounting. Some derivative instruments are associated with an anticipated transaction. In those cases, hedge effectiveness criteria also require that it be probable that the underlying transaction occurs. Instruments that meet these hedging criteria are formally designated as hedges at the inception of the derivative contract. To determine the fair values of derivative instruments, we use a variety of methods and assumptions that are based on market conditions and risks existing at each balance sheet date. For the majority of financial instruments including most derivatives, long-term investments and long-term debt, standard market conventions and techniques such as discounted cash flow analysis, option pricing models, replacement cost, and termination cost are used to determine fair value. All methods of assessing fair value result in a general approximation of value, and such value may never actually be realized. In the normal course of business, we are exposed to the effect of interest rate changes and limit these risks by following established risk management policies and procedures including the use of derivatives. To address exposure to interest rates, derivatives are used primarily to fix the rate on debt based on floating-rate indices and manage the cost of borrowing obligations. We use a variety of conventional derivative products. These derivatives typically include interest rate swaps, caps, collars and floors. We expressly prohibit the use of unconventional derivative instruments and using derivative instruments for trading or speculative purposes. Further, we have a policy of only entering into contracts with major financial institutions based upon their credit ratings and other factors. We may employ swaps, forwards or purchased options to hedge qualifying forecasted transactions. Gains and losses related to these transactions are deferred and recognized in net income as interest expense in the same period or periods that the underlying transaction occurs, expires or is otherwise terminated. Hedges that are reported at fair value and presented on the balance sheet could be characterized as cash flow hedges or fair value hedges. Interest rate caps and collars are examples of cash flow hedges. Cash flow hedges address the risk associated with future cash flows of interest payments. For all hedges held by us and which were deemed to be fully effective in meeting the hedging objectives established by our corporate policy governing interest rate risk management, no net gains or losses were reported in earnings. The changes in fair value of hedge instruments are reflected in accumulated other comprehensive income. For derivative instruments not designated as hedging instruments, the gain or loss, resulting from the change in the estimated fair value of the derivative instruments, is recognized in current earnings during the period of change. Shares Contributed by Parent Company We present shares of SL Green common stock as a contra-equity account in our financial statements. Earnings per Unit Earnings per unit was not computed in 2017 , 2016 and 2015 as there were no outstand

Property Acquisitions

Property Acquisitions	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
Property Acquisitions	Property Acquisitions During the years ended December 31, 2017 and 2016 , we did not acquire any properties from a third party. 2015 Acquisition During the year ended December 31, 2016, we finalized the purchase price allocation for the following 2015 acquisition based on facts and circumstances that existed at the acquisition date for the property (in thousands): 110 Greene Street (1)(2) Acquisition Date July 2015 Ownership Type Fee Interest Property Type Office Purchase Price Allocation: Land $ 45,120 Building and building leasehold 215,470 Above-market lease value — Acquired in-place leases 8,967 Other assets, net of other liabilities — Assets acquired 269,557 Mark-to-market assumed debt — Below-market lease value (14,557 ) Derivatives — Liabilities assumed (14,557 ) Purchase price $ 255,000 Net consideration funded by us at closing, excluding consideration financed by debt $ 255,000 Equity and/or debt investment held $ — Debt assumed $ — (1) Based on our preliminary analysis of the purchase price, we had allocated $89.3 million and $165.8 million to land and building, respectively, at 110 Greene Street. The impact to our consolidated statements of operations for the twelve months ended December 31, 2016 was an increase in rental revenue of $1.6 million for the amortization of aggregate below-market leases and an additional $3.1 million of depreciation expense. (2) We acquired a 90.0% controlling interest in this property for consideration that included the issuance of $5.0 million and $6.7 million aggregate liquidation preferences of Series P and Q Preferred Units, respectively, of limited partnership interest of the Operating Partnership and cash.

Properties Held for Sale and Pr

Properties Held for Sale and Property Dispositions	12 Months Ended
	Dec. 31, 2017
Discontinued Operations and Disposal Groups [Abstract]
Properties Held for Sale and Property Dispositions	Properties Held for Sale and Property Dispositions Properties Held for Sale As of December 31, 2017 , 115-117 Stevens Avenue in Valhalla, New York and 1-6 International Drive in Rye Brook, New York were classified as held for sale. During the fourth quarter of 2017, the Company recorded a charge of $17.8 million in connection with the reclassification of 115-117 Stevens Avenue to held for sale, and a charge of $69.1 million in connection with the reclassification of 1-6 International Drive to held for sale. These charges are included in depreciable real estate reserves in the consolidated statement of operations. The Company classified 16 Court Street in Brooklyn, New York and 125 Chubb Way in Lyndhurst, New Jersey as held for sale as of September 30, 2017; 125 Chubb Way in Lyndhurst, New Jersey and the properties at 680-750 Washington Boulevard in Stamford, Connecticut as held for sale as of June 30, 2017; and 520 White Plains Road in Tarrytown, NY and a 90% interest in 102 Greene Street in New York, NY as held for sale as of March 31, 2017. Property Dispositions The following table summarizes the properties sold during the years ended December 31, 2017 , 2016 and 2015 : Property Disposition Date Property Type (unaudited) Approximate Usable Square Feet Sales Price (1) (in millions) Gain (Loss) on Sale (2) (in millions) 125 Chubb Way (3) October 2017 Office 278,000 $ 29.5 $ (26.1 ) 16 Court Street October 2017 Office 317,600 171.0 64.9 680-750 Washington Boulevard (4) July 2017 Office 325,000 97.0 (44.2 ) 520 White Plains Road (5) April 2017 Office 180,000 21.0 (14.6 ) 102 Greene Street (6) April 2017 Retail 9,200 43.5 4.9 7 International Drive May 2016 Land 31 Acres 20.0 (6.9 ) 140 Grand Street (7) December 2015 Office 130,100 22.4 (10.5 ) 131-137 Spring Street (8) August 2015 Office 68,342 277.8 101.1 (1) Sales price represents the actual sales price for the property or the gross asset valuation for the interest in a property. (2) The gain on sale for 16 Court Street, 102 Greene Street, 131-137 Spring Street are net of $2.5 million , $0.9 million , and $4.1 million , respectively, in employee compensation awards accrued in connection with the realization of these investment gains as a bonus to certain employees that were instrumental in realizing the gain on sale. Additionally, amounts do not include adjustments for expenses recorded in subsequent periods. (3) The Company recorded a $26.1 million charge in 2017 that is included in depreciable real estate reserves in the consolidated statement of operations. (4) The Company recorded a $44.2 million charge in 2017 that is included in depreciable real estate reserves in the consolidated statement of operations. (5) The Company recorded a $14.6 million charge in 2017 that is included in depreciable real estate reserves in the consolidated statement of operations. (6) In April 2017, we closed on the sale of a 90 % interest 102 Greene Street and had subsequently accounted for our interest in the property as an investment in unconsolidated joint ventures. We sold the remaining 10 % interest in September 2017. See Note 6, "Investments in Unconsolidated Joint Ventures." (7) The Company recorded a $10.0 million charge in 2015 that is included in depreciable real estate reserves in the consolidated statement of operations. (8) We sold an 80% interest in 131-137 Spring Street and have subsequently accounted for our interest in the properties as an investment in unconsolidated joint ventures. See Note 6, "Investments in Unconsolidated Joint Ventures."

Debt and Preferred Equity Inves

Debt and Preferred Equity Investments	12 Months Ended
	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Debt and Preferred Equity Investments	Debt and Preferred Equity Investments Below is the rollforward analysis of the activity relating to our debt and preferred equity investments as of December 31, 2017 and 2016 (in thousands): December 31, 2017 December 31, 2016 Balance at beginning of period (1) $ 1,640,412 $ 1,670,020 Debt investment originations/accretion (2) 1,142,591 1,009,176 Preferred Equity investment originations/accretion (2) 144,456 5,698 Redemptions/sales/syndications/amortization (3) (813,418 ) (1,044,482 ) Balance at end of period (1) $ 2,114,041 $ 1,640,412 (1) Net of unamortized fees, discounts, and premiums. (2) Accretion includes amortization of fees and discounts and paid-in-kind investment income. (3) Certain participations in debt investments that were sold or syndicated did not meet the conditions for sale accounting are included in other assets and other liabilities on the consolidated balance sheets. Debt Investments As of December 31, 2017 and 2016 , we held the following debt investments with an aggregate weighted average current yield of 9.31% , excluding our investment in Two Herald Square, at December 31, 2017 (in thousands): Loan Type December 31, 2017 Future Funding Obligations December 31, 2017 Senior Financing December 31, 2017 Carrying Value (1) December 31, 2016 Carrying Value (1) Maturity Date (2) Fixed Rate Investments: Mortgage/Jr. Mortgage Loan (3) $ — $ — $ 250,464 $ — April 2017 Mortgage Loan (4) — — 26,366 26,311 February 2019 Loan Type December 31, 2017 Future Funding Obligations December 31, 2017 Senior Financing December 31, 2017 Carrying Value (1) December 31, 2016 Carrying Value (1) Maturity Date (2) Mortgage Loan — — 239 380 August 2019 Mezzanine Loan (5a) — 1,160,000 204,005 — March 2020 Mezzanine Loan — 15,000 3,500 3,500 September 2021 Mezzanine Loan — 147,000 24,913 — April 2022 Mezzanine Loan — 86,976 12,699 12,692 November 2023 Mezzanine Loan (5b) — 115,000 12,932 12,925 June 2024 Mezzanine Loan — 95,000 30,000 30,000 January 2025 Mezzanine Loan — 340,000 15,000 15,000 November 2026 Mezzanine Loan — 1,657,500 55,250 — June 2027 Mezzanine Loan (6) — — — 66,129 Jr. Mortgage Participation/Mezzanine Loan (7) — — — 193,422 Total fixed rate $ — $ 3,616,476 $ 635,368 $ 360,359 Floating Rate Investments: Mezzanine Loan (5c)(8) $ 795 $ — $ 15,148 $ 15,051 March 2018 Mezzanine Loan — 40,000 19,982 19,913 April 2018 Jr. Mortgage Participation — 94,546 34,947 34,844 April 2018 Mezzanine Loan 523 20,523 10,934 10,863 August 2018 Mortgage/Mezzanine Loan — — 19,940 19,840 August 2018 Mortgage Loan — 65,000 14,955 14,880 August 2018 Mortgage/Mezzanine Loan (9) — — 16,969 16,960 September 2018 Mezzanine Loan — 37,500 14,855 14,648 September 2018 Mortgage/Mezzanine Loan (10) 391 — 23,609 20,423 October 2018 Mezzanine Loan 2,325 45,025 34,879 34,502 October 2018 Mezzanine Loan — 335,000 74,755 74,476 November 2018 Mezzanine Loan (5d)(11) — 85,000 15,381 15,141 December 2018 Mezzanine Loan (5e)(11) — 65,000 14,869 14,656 December 2018 Mezzanine Loan — 33,000 26,927 26,850 December 2018 Mezzanine Loan — 175,000 59,723 56,114 December 2018 Mezzanine Loan — 45,000 12,174 12,104 January 2019 Mortgage/Mezzanine Loan (5f) 26,284 — 162,553 — January 2019 Mezzanine Loan 5,372 25,289 8,550 5,410 January 2019 Mezzanine Loan — 38,000 21,939 21,891 March 2019 Mezzanine Loan 11 174,947 37,250 — April 2019 Mezzanine Loan — 265,000 24,830 24,707 April 2019 Mortgage/Jr. Mortgage Participation Loan 27,617 199,733 71,832 65,554 August 2019 Mezzanine Loan 2,034 189,829 37,851 37,322 September 2019 Mortgage/Mezzanine Loan 36,391 — 143,919 111,819 September 2019 Mezzanine Loan — 350,000 34,737 — October 2019 Mortgage/Mezzanine Loan 25,643 — 43,845 33,682 January 2020 Mezzanine Loan (12) 3,621 555,379 75,834 125,911 January 2020 Mezzanine Loan 6,913 34,337 11,259 — July 2020 Mezzanine Loan (13) 51,494 310,654 75,428 63,137 November 2020 Mortgage and Mezzanine Loan 42,510 — 88,989 — December 2020 Loan Type December 31, 2017 Future Funding Obligations December 31, 2017 Senior Financing December 31, 2017 Carrying Value (1) December 31, 2016 Carrying Value (1) Maturity Date (2) Mortgage and Mezzanine Loan — — 35,152 — December 2020 Jr. Mortgage Participation/Mezzanine Loan — 60,000 15,635 15,606 July 2021 Mezzanine Loan — 280,000 34,600 — August 2022 Mortgage/Mezzanine Loan (14) — — — 29,998 Mezzanine Loan (15) — — — 64,505 Mezzanine Loan (16) — — — 15,369 Mortgage/Mezzanine Loan (6) — — — 32,847 Mortgage/Mezzanine Loan (6) — — — 22,959 Mezzanine Loan (17) — — — 14,957 Mortgage/Mezzanine Loan (18) — — — 145,239 Total floating rate $ 231,924 $ 3,523,762 $ 1,334,250 $ 1,232,178 Total $ 231,924 $ 7,140,238 $ 1,969,618 $ 1,592,537 (1) Carrying value is net of discounts, premiums, original issue discounts and deferred origination fees. (2) Represents contractual maturity, excluding any unexercised extension options. (3) These loans were purchased at par in April and May 2017 and were in maturity default at the time of acquisition. At the time the loans were purchased, the Company expected to collect all contractually required payments, including interest. In August 2017, the Company determined that it was probable that the loans would not be repaid in full and therefore, the loans were put on non-accrual status. No impairment was recorded as the Company believes that the fair value of the property exceeds the carrying amount of the loans. The loans had an outstanding balance, including accrued interest, of $259.3 million at the time that they were put on non-accrual status. (4) In September 2014, we acquired a $26.4 million mortgage loan at a $0.2 million discount and a $5.7 million junior mortgage participation at a $5.7 million discount. The junior mortgage participation was a nonperforming loan at acquisition, is currently on non-accrual status and has no carrying value. (5) Carrying value is net of the following amounts that were sold or syndicated, which are included in other assets and other liabilities on the consolidated balance sheets as a result of the transfers not meeting the conditions for sale accounting: (a) $1.2 million , (b) $12.0 million , (c) $5.1 million (d) $14.6 million , (e) $14.1 million , and (f) $21.2 million . (6) This loan was repaid in June 2017. (7) This loan was repaid in March 2017. (8) This loan was extended in March 2018. (9) This loan was extended in August 2017. (10) This loan was extended in September 2017. (11) This loan was extended in December 2017. (12) $66.1 million of outstanding principal was syndicated in February 2017. (13) This loan was extended in November 2017. (14) This loan was repaid in December 2017. (15) This loan was repaid in November 2017. (16) This loan was repaid in September 2017. (17) This loan was contributed to a joint venture in May 2017. (18) This loan was repaid in January 2017. Preferred Equity Investments As of December 31, 2017 and 2016 , we held the following preferred equity investments with an aggregate weighted average current yield of 6.99% at December 31, 2017 (in thousands): Type December 31, 2017 Future Funding Obligations December 31, 2017 December 31, 2017 (1) December 31, 2016 (1) Mandatory Redemption (2) Preferred Equity $ — $ 272,000 $ 144,423 $ — April 2021 Preferred Equity (3) — — — 9,982 Preferred Equity (4) — — — 37,893 $ — $ 272,000 $ 144,423 $ 47,875 (1) Carrying value is net of deferred origination fees. (2) Represents contractual maturity, excluding any unexercised extension options. (3) This investment was redeemed in May 2017. (4) This investment was redeemed in April 2017. The following table is a rollforward of our total loan loss reserves at December 31, 2017 , 2016 and 2015 (in thousands): December 31, 2017 2016 2015 Balance at beginning of year $ — $ — $ — Expensed — — — Recoveries — — — Charge-offs and reclassifications — — — Balance at end of period $ — $ — $ — At December 31, 2017 , 2016 and 2015 , all debt and preferred equity investments were performing in accordance with the terms of the relevant investments, with the exception of a mortgage and junior mortgage participation purchased in maturity default in May 2017 and April 2017, respectively, as discussed in subnote 3 of the Debt Investments table above and a junior mortgage participation acquired in September 2014, which was acquired for zero and has a carrying value of zero , as discussed in subnote 4 of the Debt Investments table above. We have determined that we have one portfolio segment of financing receivables at December 31, 2017 and 2016 comprising commercial real estate which is primarily recorded in debt and preferred equity investments. Included in other assets is an additional amount of financing receivables totaling $93.4 million and $144.5 million at December 31, 2017 and 2016 , respectively. No financing receivables were 90 days past due at December 31, 2017 , with the exception of a mortgage and junior mortgage participation purchased in maturity default in May 2017 and April 2017, respectively, as discussed in subnote 3 of the Debt Investments table above.

Investments in Unconsolidated J

Investments in Unconsolidated Joint Ventures	12 Months Ended
	Dec. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
Investments in Unconsolidated Joint Ventures	Investments in Unconsolidated Joint Ventures We have investments in several real estate joint ventures with various partners. As of December 31, 2017 and December 31, 2016 none of our investments in unconsolidated joint ventures were VIEs. All of the investments below are voting interest entities. As we do not control the joint ventures listed below, we account for them under the equity method of accounting. The table below provides general information on each of our joint ventures as of December 31, 2017 : Property Partner Ownership Interest (1) Economic Interest (1) Unaudited Approximate Square Feet Acquisition Date (2) Acquisition Price (2) (in thousands) 131-137 Spring Street Invesco Real Estate 20.00% 20.00% 68,342 August 2015 $ 277,750 Mezzanine Loan (3) Private Investors 33.33% 33.33% — May 2017 15,000 (1) Ownership interest and economic interest represent the Company's interests in the joint venture as of December 31, 2017 . Changes in ownership or economic interests within the current year are disclosed in the notes below. (2) Acquisition date and price represent the date on which the Company initially acquired an interest in the joint venture and the actual or implied gross purchase price for the joint venture on that date. Acquisition date and price are not adjusted for subsequent acquisitions or dispositions of interest. (3) In May 2017, the Company contributed a mezzanine loan secured by a commercial property in midtown Manhattan to a joint venture and retained a 33.33% interest in the venture. The carrying value is net of $10.0 million that was sold, which is included in other assets and other liabilities on the consolidated balance sheets as a result of the transfers not meeting the conditions for sale accounting. The loan matures in November 2018. Acquisition, Development and Construction Arrangements Based on the characteristics of the following arrangements, which are similar to those of an investment, combined with the expected residual profit of not greater than 50% , we have accounted for these debt and preferred equity investments under the equity method. As of December 31, 2017 and 2016 , the carrying value for acquisition, development and construction arrangements were as follows (in thousands): Loan Type December 31, 2017 December 31, 2016 Maturity Date Mezzanine Loan and Preferred Equity (1) $ 100,000 $ 100,000 March 2018 Mezzanine Loan (2) 26,716 24,542 July 2036 $ 126,716 $ 124,542 (1) The mezzanine loan was repaid and the preferred equity interest was redeemed in March 2018. (2) The Company has the ability to convert this loan into an equity position starting in 2021 and the borrower is able to force this conversion in 2024. Sale of Joint Venture Interests or Properties The following table summarizes the investments in unconsolidated joint ventures sold during the years ended December 31, 2017 , 2016 , and 2015 : Property Ownership Interest Disposition Date Type of Sale Gross Asset Valuation (in thousands) (1) Gain on Sale (in thousands) (2) 102 Greene Street 10.00% September 2017 Ownership Interest $ 43,500 $ 283 (1) Represents implied gross valuation for the joint venture or sales price of the property. (2) Represents the Company's share of the gain. In May 2017, our investment in a joint venture that owned two mezzanine notes secured by interests in the entity that owns 76 11th Avenue was repaid after the joint venture received repayment of the underlying loans. Joint Venture Mortgages and Other Loans Payable We generally finance our joint ventures with non-recourse debt. In certain cases we have provided guarantees or master leases for tenant space, which terminate upon the satisfaction of specified circumstances or repayment of the underlying loans. The first mortgage notes and other loans payable collateralized by the respective joint venture properties and assignment of leases at December 31, 2017 and 2016 , respectively, are as follows (amounts in thousands): Property Economic Interest (1) Maturity Date Interest Rate (2) December 31, 2017 December 31, 2016 Floating Rate Debt: 131-137 Spring Street 20.00 % August 2020 L+ 1.55% $ 141,000 $ 141,000 Total joint venture mortgages and other loans payable $ 141,000 $ 141,000 Deferred financing costs, net (2,862 ) (3,970 ) Total joint venture mortgages and other loans payable, net $ 138,138 $ 137,030 (1) Economic interest represents the Company's interests in the joint venture as of December 31, 2017 . Changes in ownership or economic interests, if any, within the current year are disclosed in the notes to the investment in unconsolidated joint ventures note above. (2) Interest rate as of December 31, 2017 . Floating rate debt is presented with the stated interest rate spread over 30-day LIBOR, unless otherwise specified. The combined balance sheets for the unconsolidated joint ventures, at December 31, 2017 and 2016 are as follows (in thousands): December 31, 2017 December 31, 2016 Assets Commercial real estate property, net $ 273,116 $ 279,451 Debt and preferred equity investments, net 141,716 273,749 Other assets 15,735 18,922 Total assets $ 430,567 $ 572,122 Liabilities and members' equity Mortgages and other loans payable, net $ 138,138 $ 137,030 Other liabilities 18,908 22,185 Members' equity 273,521 412,907 Total liabilities and members' equity $ 430,567 $ 572,122 Company's investments in unconsolidated joint ventures $ 130,217 $ 174,127 The combined statements of operations for the unconsolidated joint ventures for the years ended December 31, 2017 , 2016 , and 2015 are as follows (in thousands): Year Ended December 31, 2017 2016 2015 Total revenues $ 35,204 $ 38,524 $ 19,855 Operating expenses 877 1,238 1,686 Real estate taxes 1,389 1,192 1,262 Interest expense, net of interest income 3,769 2,895 1,070 Amortization of deferred financing costs 1,114 1,108 462 Transaction related costs — — 5,262 Depreciation and amortization 8,405 8,404 3,207 Total expenses $ 15,554 $ 14,837 $ 12,949 Net income $ 19,650 $ 23,687 $ 6,906 Company's equity in net income from unconsolidated joint ventures 14,192 14,509 8,841

Mortgages and Other Loans Payab

Mortgages and Other Loans Payable	12 Months Ended
	Dec. 31, 2017
Mortgage Note and Other Loans Payable
Mortgages and Other Loans Payable	Mortgages and Other Loans Payable The first mortgages and other loans payable collateralized by the respective properties and assignment of leases or debt investments at December 31, 2017 and 2016 , respectively, were as follows (amounts in thousands): Property Maturity Date Interest Rate (1) December 31, 2017 December 31, 2016 Fixed Rate Debt: 919 Third Avenue (2) June 2023 5.12% $ 500,000 $ 500,000 315 West 33rd Street February 2027 4.24% 250,000 — Floating Rate Debt: 2017 Master Repurchase Agreement June 2018 L+ 2.38% $ 90,809 $ — 2016 Master Repurchase Agreement (3) — 184,642 Total mortgages and other loans payable $ 840,809 $ 684,642 Deferred financing costs, net of amortization (11,161 ) (8,574 ) Total mortgages and other loans payable, net $ 829,648 $ 676,068 (1) Interest rate as of December 31, 2017 . Floating rate debt is presented with the stated interest rate spread over 30-day LIBOR, unless otherwise specified. (2) We own a 51.0% controlling interest in the consolidated joint venture that is the borrower on this loan. (3) The master repurchase agreement was repaid in October 2017. At December 31, 2017 and 2016 , the gross book value of the properties and debt and preferred equity investments collateralizing the mortgages and other loans payable, not including assets held for sale, was approximately $1.9 billion and $1.7 billion , respectively. Master Repurchase Agreements The Company has entered into two Master Repurchase Agreements, or MRAs, known as the 2016 MRA and 2017 MRA, which provide us with the ability to sell certain debt investments with a simultaneous agreement to repurchase the same at a certain date or on demand. We seek to mitigate risks associated with our repurchase agreement by managing the credit quality of our assets, early repayments, interest rate volatility, liquidity, and market value. The margin call provisions under our repurchase facilities permit valuation adjustments based on capital markets activity, and are not limited to collateral-specific credit marks. To monitor credit risk associated with our debt investments, our asset management team regularly reviews our investment portfolio and is in contact with our borrowers in order to monitor the collateral and enforce our rights as necessary. The risk associated with potential margin calls is further mitigated by our ability to recollateralize the facility with additional assets from our portfolio of debt investments and our ability to satisfy margin calls with cash or cash equivalents. In June 2017, we entered into the 2017 MRA, with a maximum facility capacity of $300.0 million . The facility bears interest on a floating rate basis at a spread to 30-day LIBOR based on the pledged collateral and advance rate and has an initial one year term, with two one year extension options. At December 31, 2017 , the facility had a carrying value of $90.1 million , net of deferred financing costs. In July 2016, we entered into a restated 2016 MRA, with a maximum facility capacity of $300.0 million . The facility bears interest ranging from 225 and 400 basis points over 30-day LIBOR depending on the pledged collateral and has an initial two -year term, with a one year extension option. Since December 6, 2015, we have been required to pay monthly in arrears a 25 basis point fee on the excess of $150.0 million over the average daily balance during the period when the average daily balance is less than $150.0 million . At December 31, 2017 , the facility had a carrying value of $(1.2) million , representing deferred financing costs presented within other liabilities.

Corporate Indebtedness

Corporate Indebtedness	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Corporate Indebtedness	Corporate Indebtedness 2017 Credit Facility In November 2017, the Company, SL Green and the Operating Partnership entered into an amendment to the credit facility, referred to as the 2017 credit facility, that was originally entered into in November 2012, or the 2012 credit facility. The amendment resulted in the Company no longer being a borrower, and instead is providing a guarantee of the facility. The 2012 credit facility had a carrying value of $1.2 billion , net of deferred financing costs, as of the amendment date and was removed from our consolidated balance sheet and shown as a non-cash capital contribution. SL Green and the Operating Partnership remain borrowers jointly and severally obligated under the 2017 credit facility. As of December 31, 2017 , the 2017 credit facility consisted of a $1.5 billion revolving credit facility, a $1.3 billion term loan (or "Term Loan A"), and a $200.0 million term loan (or "Term Loan B") with maturity dates of March 31, 2022, March 31, 2023, and November 21, 2024, respectively. The revolving credit facility has two six -month as-of-right extension options to March 31, 2023. SL Green and the Operating Partnership also have an option, subject to customary conditions, to increase the capacity of the credit facility to $4.5 billion at any time prior to the maturity dates for the revolving credit facility and term loans without the consent of existing lenders, by obtaining additional commitments from the existing lenders and other financial institutions. As of December 31, 2017 , SL Green and the Operating Partnership had $11.8 million of outstanding letters of credit, $40.0 million drawn under the revolving credit facility and $1.5 billion outstanding under the term loan facilities, with total undrawn capacity of $1.4 billion under the 2017 credit facility. At December 31, 2017 and December 31, 2016 , the revolving credit facility had a carrying value of $30.3 million and $(6.3) million , respectively, net of deferred financing costs. The December 31, 2016 carrying value represents deferred financing costs and is presented within other liabilities. At December 31, 2017 and December 31, 2016 , the term loan facilities had a carrying value of $1.5 billion and $1.2 billion , respectively, net of deferred financing costs. The 2017 credit facility includes certain restrictions and covenants (see Restrictive Covenants below). Senior Unsecured Notes The following table sets forth our senior unsecured notes and other related disclosures as of December 31, 2017 and 2016 , respectively, by scheduled maturity date (dollars in thousands): Issuance December 31, 2017 Unpaid Principal Balance December 31, 2017 Accreted Balance December 31, 2016 Accreted Balance Coupon (1) Initial Term Maturity Date August 5, 2011 (2) $ 250,000 $ 249,953 $ 249,880 5.00 % 7 August 2018 March 16, 2010 (2) 250,000 250,000 250,000 7.75 % 10 March 2020 November 15, 2012 (3) 300,000 305,163 200,000 4.50 % 10 December 2022 December 17, 2015 (2) 100,000 100,000 100,000 4.27 % 10 December 2025 $ 900,000 $ 905,116 $ 799,880 Deferred financing costs, net (4,049 ) (4,620 ) $ 900,000 $ 901,067 $ 795,260 (1) Interest on the senior unsecured notes is payable semi-annually with principal and unpaid interest due on the scheduled maturity dates. (2) Issued by SL Green, the Operating Partnership and ROP, as co-obligors. (3) In October 2017, SL Green, the Operating Partnership, and ROP, as co-obligors, issued an additional $100.0 million of 4.50% senior unsecured notes due December 2022. The notes were priced at 105.334% . We provide a guaranty of the Operating Partnership's obligations under its 3.25% Senior Notes due 2022, which were issued in October 2017 and will mature in October 2022. As of December 31, 2017 , the 3.25% Senior Notes due 2022 had a carrying value of $499.5 million . Restrictive Covenants The terms of the 2017 credit facility and certain of our senior unsecured notes include certain restrictions and covenants which may limit, among other things, SL Green's ability to pay dividends, make certain types of investments, incur additional indebtedness, incur liens and enter into negative pledge agreements and dispose of assets, and which require compliance with financial ratios relating to the maximum ratio of total indebtedness to total asset value, a minimum ratio of EBITDA to fixed charges, a maximum ratio of secured indebtedness to total asset value and a maximum ratio of unsecured indebtedness to unencumbered asset value. The dividend restriction referred to above provides that SL Green will not during any time when a default is continuing, make distributions with respect to SL Green's common stock or other equity interests, except to enable SL Green to continue to qualify as a REIT for Federal income tax purposes. As of December 31, 2017 and 2016 , we were in compliance with all such covenants. Principal Maturities Combined aggregate principal maturities of mortgages and other loans payable, and senior unsecured notes as of December 31, 2017 , including as-of-right extension options and put options, were as follows (in thousands): Scheduled Principal Senior Total 2018 $ — $ 90,809 $ 250,000 $ 340,809 2019 — — — — 2020 — — 250,000 250,000 2021 — — — — 2022 — — 300,000 300,000 Thereafter — 750,000 100,000 850,000 $ — $ 840,809 $ 900,000 $ 1,740,809 Consolidated interest expense, excluding capitalized interest, was comprised of the following (in thousands): Year Ended December 31, 2017 2016 2015 Interest expense before capitalized interest $ 124,507 $ 110,393 $ 120,467 Interest capitalized (533 ) (1,171 ) (1,107 ) Interest income (5 ) (14 ) (18 ) Interest expense, net $ 123,969 $ 109,208 $ 119,342

Preferred Units

Preferred Units	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Preferred Units	Preferred Units Through a consolidated subsidiary, we have authorized up to 109,161 3.50% Series A Preferred Units of limited partnership interest, or the Subsidiary Series A Preferred Units, with a liquidation preference of $1,000.00 per unit. In August 2015, the Company issued 109,161 Subsidiary Series A Preferred Units in conjunction with an acquisition. The Subsidiary Series A Preferred unitholders receive annual dividends of $35.00 per unit paid on a quarterly basis and dividends are cumulative, subject to certain provisions. The Subsidiary Series A Preferred Units can be redeemed at any time, at the option of the unitholder, either for cash or are convertible on a one-for-one basis, into the Series B Preferred Units of limited partnership interest, or the Subsidiary Series B Preferred Units. The Subsidiary Series B Preferred Units can be converted at any time, at the option of the unitholder, into a number of common stock equal to 6.71348 shares of SL Green common stock for each Subsidiary Series B Preferred Unit. As of December 31, 2017 , no Subsidiary Series B Preferred Units have been issued. ASC 815 Derivatives and Hedging requires bifurcation of certain embedded derivative instruments, such as conversion features in convertible equity instruments, and their measurement at fair value for accounting purposes. The conversion feature embedded in the Subsidiary Series A Preferred Units was evaluated, and it was determined that the conversion feature should be bifurcated from its host instrument and accounted for as a freestanding derivative. The derivative is reported as a derivative liability in accrued interest and other liabilities on the accompanying consolidated balance sheet and is adjusted to its fair value at each reporting date, with a corresponding adjustment to interest expense, net of interest income. The embedded derivative for the Subsidiary Series A Preferred Units was initially recorded at a fair value of zero on July 22, 2015, the date of issuance. At December 31, 2017 , the carrying amount of the derivative remained at zero .

Partners' Capital

Partners' Capital	12 Months Ended
	Dec. 31, 2017
Partners' Capital Notes [Abstract]
Partners' Capital	Partners' Capital Since consummation of the Merger on January 25, 2007, the Operating Partnership has owned all the economic interests in us either by direct ownership or by indirect ownership through our general partner, which is its wholly-owned subsidiary. Intercompany transactions between SL Green and us are generally recorded as contributions and distributions.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements We are required to disclose fair value information with regard to our financial instruments, whether or not recognized in the consolidated balance sheets, for which it is practical to estimate fair value. The FASB guidance defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants on the measurement date. We measure and/or disclose the estimated fair value of financial assets and liabilities based on a hierarchy that distinguishes between market participant assumptions based on market data obtained from sources independent of the reporting entity and the reporting entity’s own assumptions about market participant assumptions. This hierarchy consists of three broad levels: Level 1 - quoted prices (unadjusted) in active markets for identical assets or liabilities that the reporting entity can access at the measurement date; Level 2 - inputs other than quoted prices included within Level 1, that are observable for the asset or liability, either directly or indirectly; and Level 3 - unobservable inputs for the asset or liability that are used when little or no market data is available. We follow this hierarchy for our assets and liabilities measured at fair value on a recurring and nonrecurring basis. In instances in which the determination of the fair value measurement is based on inputs from different levels of the fair value hierarchy, the level in the fair value hierarchy within which the entire fair value measurement falls is based on the lowest level of input that is significant to the fair value measurement in its entirety. Our assessment of the significance of the particular input to the fair value measurement in its entirety requires judgment and considers factors specific to the asset or liability. The following tables set forth the assets and liabilities that we measure at fair value on a recurring and non-recurring basis by their levels in the fair value hierarchy at December 31, 2017 and 2016 (in thousands): December 31, 2017 Total Level 1 Level 2 Level 3 Assets: Interest rate cap and swap agreements (included in other assets) $ 167 $ — $ 167 $ — December 31, 2016 Total Level 1 Level 2 Level 3 Assets: Interest rate cap and swap agreements (included in other assets) $ — $ — $ — $ — We determine other than temporary impairment in real estate investments and debt and preferred equity investments, including intangibles primarily utilizing cash flow projections that apply, among other things, estimated revenue and expense growth rates, discount rates and capitalization rates, as well as sales comparison approach, which utilizes comparable sales, listings and sales contracts. All of which are classified as Level 3 inputs. As of December 31, 2017 , we held notes receivable totaling $250.0 million , which were purchased at par, and were in maturity default at the time of acquisition. In August 2017, the Company determined that it was probable that the loans would not be repaid in full and therefore, the loans were put on non-accrual status. The loans had an outstanding balance including accrued interest of $259.3 million at the time that they were put on non accrual status. The Company has initiated proceedings to foreclose on the property, and expects to take control of the property unless the buyer is able to repay the principal and interest, including default interest and fees, on the notes receivable in full prior to the completion of the foreclosure process. We believe the collateral value is sufficient to recover the carrying amounts of the notes receivable. The fair value of derivative instruments is based on current market data received from financial sources that trade such instruments and are based on prevailing market data and derived from third party proprietary models based on well-recognized financial principles and reasonable estimates about relevant future market conditions, which are classified as Level 2 inputs. The financial assets and liabilities that are not measured at fair value on our consolidated balance sheets include cash and cash equivalents, restricted cash, accounts receivable, accounts payable and accrued expenses, debt and preferred equity investments, mortgages and other loans payable and other secured and unsecured debt. The carrying amount of cash and cash equivalents, restricted cash, accounts receivable, and accounts payable and accrued expenses reported in our consolidated balance sheets approximates fair value due to the short term nature of these instruments. The fair value of debt and preferred equity investments, which is classified as Level 3, is estimated by discounting the future cash flows using current interest rates at which similar loans with the same maturities would be made to borrowers with similar credit ratings. The fair value of borrowings, which is classified as Level 3, is estimated by discounting the contractual cash flows of each debt instrument to their present value using adjusted market interest rates, which is provided by a third-party specialist. The following table provides the carrying value and fair value of these financial instruments as of December 31, 2017 and December 31, 2016 (in thousands): December 31, 2017 December 31, 2016 Carrying Value (1) Fair Value Carrying Value (1) Fair Value Debt and preferred equity investments $ 2,114,041 (2) $ 1,640,412 (2) Fixed rate debt $ 1,655,116 $ 1,715,501 $ 2,099,880 $ 2,183,042 Variable rate debt 90,809 92,087 567,642 580,083 $ 1,745,925 $ 1,807,588 $ 2,667,522 $ 2,763,125 (1) Amounts exclude net deferred financing costs. (2) At December 31, 2017 , debt and preferred equity investments had an estimated fair value ranging between $2.1 billion and $2.3 billion . At December 31, 2016 , debt and preferred equity investments had an estimated fair value ranging between $1.6 billion and $1.8 billion . Disclosure about fair value of financial instruments was based on pertinent information available to us as of December 31, 2017 and 2016 . 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.

Financial Instruments_ Derivati

Financial Instruments: Derivatives and Hedging	12 Months Ended
	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Financial Instruments: Derivatives and Hedging	Financial Instruments: Derivatives and Hedging In the normal course of business, we use a variety of commonly used derivative instruments, such as interest rate swaps, caps, collar and floors, to manage, or hedge interest rate risk. We hedge our exposure to variability in future cash flows for forecasted transactions in addition to anticipated future interest payments on existing debt. We recognize all derivatives on the balance sheets at fair value. Derivatives that are not hedges are adjusted to fair value through earnings. If a derivative is a hedge, depending on the nature of the hedge, changes in the fair value of the derivative will either be offset against the change in fair value of the hedge asset, liability, or firm commitment through earnings, or recognized in other comprehensive income until the hedged item is recognized in earnings. The ineffective portion of a derivative's change in fair value will be immediately recognized in earnings. Reported net income and equity may increase or decrease prospectively, depending on future levels of interest rates and other variables affecting the fair values of derivative instruments and hedged items, but will have no effect on cash flows. Currently, all of our designated derivative instruments are effective hedging instruments. The following table summarizes the notional value at inception and fair value of our consolidated derivative financial instruments at December 31, 2017 based on Level 2 information. The notional value is an indication of the extent of our involvement in these instruments at that time, but does not represent exposure to credit, interest rate or market risks (amounts in thousands). Notional Value Strike Rate Effective Date Expiration Date Balance Sheet Location Fair Value Interest Rate Swap $ 21,394 12.000 % January 2017 January 2019 Other Assets $ 167 $ 167 During the year ended December 31, 2017 , we recorded a $0.2 million gain on the changes in the fair value, which is included in investment income in the consolidated statements of operations. We did not record any changes in the fair value for the years ended December 31, 2016 , and 2015 . The Company has agreements with each of its derivative counterparties that contain a provision where if the Company either defaults or is capable of being declared in default on any of its indebtedness, then the Company could also be declared in default on its derivative obligations. As of December 31, 2017 , the fair value of derivatives in a net liability position including accrued interest but excluding any adjustment for nonperformance risk related to these agreements was zero . As of December 31, 2017 , the Company has not posted any collateral related to these agreements and was not in breach of any agreement provisions. If the Company had breached any of these provisions, it could have been required to settle its obligations under the agreements at their aggregate termination value of zero at December 31, 2017 . Gains and losses on terminated hedges are included in accumulated other comprehensive income, and are recognized into earnings over the term of the related senior unsecured notes. As of December 31, 2017 and 2016 , the deferred net losses from these terminated hedges, which are included in accumulated other comprehensive income relating to net unrealized loss on derivative instruments, was approximately $1.3 million and $1.6 million , respectively. Over time, the realized and unrealized gains and losses held in accumulated other comprehensive income will be reclassified into earnings as an adjustment to interest expense in the same periods in which the hedged interest payments affect earnings. We estimate that $0.4 million of the current balance held in accumulated other comprehensive income will be reclassified into interest expense within the next 12 months. The following table presents the effect of our derivative financial instruments that are designated and qualify as hedging instruments on the consolidated statements of operations for the years ended December 31, 2017 , 2016 , and 2015 , respectively (in thousands): Amount of Loss Recognized in Other Comprehensive Loss (Effective Portion) Location of Loss Reclassified from Accumulated Other Comprehensive Loss into Income Amount of Loss Reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion) Location of Gain Recognized in Income on Derivative Amount of Gain Recognized into Income (Ineffective Portion) Year Ended December 31, Year Ended December 31, Year Ended December 31, Derivative 2017 2016 2015 2017 2016 2015 2017 2016 2015 Interest Rate Swap $ — $ (13 ) $ (109 ) Interest expense $ 359 $ 611 $ 999 Interest expense $ — $ 3 $ 3

Rental Income

Rental Income	12 Months Ended
	Dec. 31, 2017
Leases [Abstract]
Rental Income	Rental Income We are the lessor and the sublessor to tenants under operating leases with expiration dates ranging from January 1, 2018 to 2052. The minimum rental amounts due under the leases are generally either subject to scheduled fixed increases or adjustments. The leases generally also require that the tenants reimburse us for increases in certain operating costs and real estate taxes above their base year costs. Approximate future minimum rents to be received over the next five years and thereafter for non-cancelable operating leases in effect at December 31, 2017 for the consolidated properties, including consolidated joint venture properties, are as follows (in thousands): 2018 $ 606,408 2019 578,008 2020 515,413 2021 466,618 2022 397,288 Thereafter 1,873,772 $ 4,437,507

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2017
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Cleaning/ Security/ Messenger and Restoration Services Alliance Building Services, or Alliance, and its affiliates are partially owned by Gary Green, a son of Stephen L. Green, the chairman of SL Green's board of directors, and provide services to certain properties owned by us. Alliance’s affiliates include First Quality Maintenance, L.P., or First Quality, Classic Security LLC, Bright Star Couriers LLC and Onyx Restoration Works, and provide cleaning, extermination, security, messenger, and restoration services, respectively. In addition, First Quality has the non-exclusive opportunity to provide cleaning and related services to individual tenants at our properties on a basis separately negotiated with any tenant seeking such additional services. The Service Corporation has entered into an arrangement with Alliance whereby it will receive a profit participation above a certain threshold for services provided by Alliance to certain tenants at certain buildings above the base services specified in their lease agreements. Income earned from profit participation, which is included in other income on the consolidated statements of operations, was $3.4 million , $3.3 million and $3.3 million for the years ended December 31, 2017 , 2016 and 2015 respectively. We also recorded expenses, inclusive of capitalized expenses, of $10.0 million , $8.1 million and $9.9 million for the years ended December 31, 2017 , 2016 and 2015 respectively, for these services (excluding services provided directly to tenants). Allocated Expenses from SL Green Property operating expenses include an allocation of salary and other operating costs from SL Green based on square footage of the related properties. Such amount was approximately $12.8 million , $11.5 million and $10.4 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. Insurance We obtained insurance coverage through an insurance program administered by SL Green. In connection with this program, we incurred insurance expense of approximately $5.4 million , $5.9 million , and $6.6 million for the years ended December 31, 2017 , 2016 and 2015 respectively. Related Party Payable to SL Green On August 22, 2016, we issued a promissory note to our parent company in the amount of $23.8 million which bears interest at an annual rate of 6.0% , compounded quarterly, and matures on August 22, 2018.

Benefit Plans

Benefit Plans	12 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
Benefit Plans	Benefit Plans The building employees are covered by multi-employer defined benefit pension plans and post-retirement health and welfare plans. We participate in the Building Service 32BJ, or Union, Pension Plan and Health Plan. The Pension Plan is a multi-employer, non-contributory defined benefit pension plan that was established under the terms of collective bargaining agreements between the Service Employees International Union, Local 32BJ, the Realty Advisory Board on Labor Relations, Inc. and certain other employees. This Pension Plan is administered by a joint board of trustees consisting of union trustees and employer trustees and operates under employer identification number 13-1879376. The Pension Plan year runs from July 1 to June 30. Employers contribute to the Pension Plan at a fixed rate on behalf of each covered employee. Separate actuarial information regarding such pension plans is not made available to the contributing employers by the union administrators or trustees, since the plans do not maintain separate records for each reporting unit. However, on September 28, 2015, and September 28, 2016, and September 28, 2017, the actuary certified that for the plan years beginning July 1, 2015, July 1, 2016, and July 1, 2017, the Pension Plan was in critical status under the Pension Protection Act of 2006. The Pension Plan trustees adopted a rehabilitation plan consistent with this requirement. No surcharges have been paid to the Pension Plan as of December 31, 2017 . For the Pension Plan years ended June 30, 2017 , 2016 , and 2015 , the plan received contributions from employers totaling $257.8 million , $249.5 million , and $221.9 million , respectively. Our contributions to the Pension Plan represent less than 5.0% of total contributions to the plan. The Health Plan was established under the terms of collective bargaining agreements between the Union, the Realty Advisory Board on Labor Relations, Inc. and certain other employers. The Health Plan provides health and other benefits to eligible participants employed in the building service industry who are covered under collective bargaining agreements, or other written agreements, with the Union. The Health Plan is administered by a Board of Trustees with equal representation by the employers and the Union and operates under employer identification number 13-2928869. The Health Plan receives contributions in accordance with collective bargaining agreements or participation agreements. Generally, these agreements provide that the employers contribute to the Health Plan at a fixed rate on behalf of each covered employee. For the Health Plan years ended, June 30, 2017 , 2016 and 2015 , the plan received contributions from employers totaling $1.3 billion , $1.2 billion and $1.1 billion , respectively. Our contributions to the Health Plan represent less than 5.0% of total contributions to the plan. Contributions we made to the multi-employer plans for the years ended December 31, 2017 , 2016 and 2015 are included in the table below (in thousands): Benefit Plan 2017 2016 2015 Pension Plan $ 2,269 $ 2,219 $ 1,533 Health Plan 6,764 6,366 4,843 Other plans 865 902 3,300 Total plan contributions $ 9,898 $ 9,487 $ 9,676

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal Proceedings As of December 31, 2017 , we were not involved in any material litigation nor, to management's knowledge, was any material litigation threatened against us or our portfolio which if adversely determined could have a material adverse impact on us. Environmental Matters Our management believes that the properties are in compliance in all material respects with applicable Federal, state and local ordinances and regulations regarding environmental issues. Management is not aware of any environmental liability that it believes would have a materially adverse impact on our financial position, results of operations or cash flows. Management is unaware of any instances in which it would incur significant environmental cost if any of our properties were sold. Ground Leases Arrangements The property located at 711 Third Avenue operates under an operating sub-lease with an expiration date of 2033 and five options to renew for an additional 10 years each. The ground rent was reset in July 2011. Following the reset, we are responsible for ground rent payments of $5.25 million annually through July 2016 and then $5.5 million annually thereafter on the 50% portion of the fee that we do not own. The property located at 461 Fifth Avenue operates under a ground lease ( $2.1 million of ground rent annually) with an expiration date of 2027 and two options to renew for an additional 21 years each, followed by a third option for 15 years. We also have an option to purchase the fee position for a fixed price on a specific date. The property located at 625 Madison Avenue operates under a ground lease ( $4.6 million of ground rent annually) with an expiration date of 2022 and two options to renew for an additional 23 years. The property located at 1185 Avenue of the Americas operates under a ground lease ( $6.9 million of ground rent annually) with an expiration date of 2043 and an option to renew for an additional 23 years. The property located at 919 Third Avenue operates under a ground lease ( $0.9 million of ground rent annually) with an expiration date of 2066. The fee interest in the land at 919 Third Avenue is owned by SL Green. The property located at 1055 Washington Boulevard operates under a ground lease ( $0.6 million of ground rent annually) with an expiration date of 2090. The following is a schedule of future minimum lease payments under non-cancellable operating leases with initial terms in excess of one year as of December 31, 2017 (in thousands): Non-cancellable operating leases 2018 $ 20,586 2019 20,586 2020 20,586 2021 20,736 2022 18,580 Thereafter 289,622 Total minimum lease payments $ 390,696

Quarterly Financial Data of the

Quarterly Financial Data of the Company (unaudited)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Data of the Company (unaudited)	Quarterly Financial Data of the Company (unaudited) Summarized quarterly financial data for the years ended December 31, 2017 and 2016 , was as follows (in thousands): 2017 Quarter Ended December 31 September 30 June 30 March 31 Total revenues $ 241,463 $ 241,908 $ 251,812 $ 232,355 Income before equity in net income from unconsolidated joint ventures, equity in net gain on sale of interest in unconsolidated joint venture, gain (loss) on sale of real estate, depreciable real estate reserves and loss on early extinguishment of debt $ 76,973 $ 61,766 $ 83,947 $ 63,149 Equity in net income from unconsolidated joint ventures 3,830 2,927 3,180 4,255 Equity in net gain on sale of interest in unconsolidated joint venture 387 282 — 3 Gain on sale of real estate 64,779 114 4,933 — Depreciable real estate reserves (86,364 ) (379 ) (29,063 ) (56,265 ) Net income 59,605 64,710 62,997 11,142 Net (income) loss attributable to noncontrolling interests in other partnerships (2,147 ) 1,467 18,134 (14 ) Preferred units dividend (956 ) (955 ) (955 ) (953 ) Net income attributable to ROP common unitholder $ 56,502 $ 65,222 $ 80,176 $ 10,175 2016 Quarter Ended December 31 September 30 June 30 March 31 Total revenues $ 232,658 $ 271,336 $ 231,758 $ 239,664 Income from continuing operations before equity in net income from unconsolidated joint ventures, and loss on sale of real estate $ 66,056 $ 98,647 $ 71,254 $ 69,743 Equity in net income from unconsolidated joint ventures 4,110 4,276 3,666 2,457 Loss on sale of real estate, net (10 ) — (6,899 ) — Net income 70,156 102,923 68,021 72,200 Net income attributable to noncontrolling interests in other partnerships (1,071 ) (1,279 ) (2,062 ) (12 ) Preferred units dividend (956 ) (955 ) (955 ) (955 ) Net income attributable to ROP common unitholder $ 68,129 $ 100,689 $ 65,004 $ 71,233

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Segment Information	Segment Information We are engaged in acquiring, owning, managing and leasing commercial properties in the New York metropolitan area and have two reportable segments, real estate and debt and preferred equity investments. We evaluate real estate performance and allocate resources based on earnings contribution to income from continuing operations. The primary sources of revenue are generated from tenant rents and escalations and reimbursement revenue. Real estate property operating expenses consist primarily of security, maintenance, utility costs, real estate taxes and ground rent expense (at certain applicable properties). See Note 5, "Debt and Preferred Equity Investments," for additional details on our debt and preferred equity investments. Selected results of operations for the years ended December 31, 2017 , 2016 and 2015 and selected asset information as of December 31, 2017 and 2016 , regarding our operating segments are as follows (in thousands): Real Estate Segment Debt and Preferred Equity Segment Total Company Total revenues: Years ended: December 31, 2017 $ 773,561 $ 193,977 $ 967,538 December 31, 2016 761,314 214,102 975,416 December 31, 2015 742,585 182,648 925,233 Income before equity in net gain on sale of interest in unconsolidated joint venture, gain (loss) on sale of real estate, depreciable real estate reserves and loss on early extinguishment of debt Years ended: December 31, 2017 $ 129,558 $ 170,469 $ 300,027 December 31, 2016 115,213 204,996 320,209 December 31, 2015 108,937 163,684 272,621 Total assets As of: December 31, 2017 $ 6,182,300 $ 2,359,208 $ 8,541,508 December 31, 2016 6,786,479 1,968,134 8,754,613 Income from continuing operations represents total revenues less total expenses for the real estate segment and total investment income less allocated interest expense for the debt and preferred equity segment. Interest costs for the debt and preferred equity segment includes actual costs incurred for investments collateralizing the MRAs. Interest is imputed on the remaining investments using our corporate borrowing cost. We also allocate loan loss reserves, net of recoveries, and transaction related costs to the debt and preferred equity segment. We do not allocate marketing, general and administrative expenses to the debt and preferred equity segment since the use of personnel and resources is dependent on transaction volume between the two segments and varies period over period. In addition, we base performance on the individual segments excluding marketing, general and administrative expenses. All other expenses, except interest, relate entirely to the real estate assets. There were no transactions between the above two segments. The table below reconciles income from continuing operations to net income for the years ended December 31, 2017 , 2016 and 2015 (in thousands): Year ended December 31, 2017 2016 2015 Income before equity in net gain on sale of interest in unconsolidated joint venture/real estate, gain (loss) on sale of real estate, depreciable real estate reserves, and loss on early extinguishment of debt. $ 300,027 $ 320,209 $ 272,621 Equity in net gain on sale of interest in unconsolidated joint venture/real estate 672 — — Gain (loss) on sale of real estate, net 69,826 (6,909 ) 100,190 Depreciable real estate reserves (172,071 ) — (9,998 ) Loss on early extinguishment of debt — — (49 ) Net income $ 198,454 $ 313,300 $ 362,764

Schedule II_Valuation and Quali

Schedule II—Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2017
Valuation and Qualifying Accounts [Abstract]
Schedule II—Valuation and Qualifying Accounts	Schedule II—Valuation and Qualifying Accounts December 31, 2017 (in thousands) Column A Column B Column C Column D Column E Description Balance at Beginning of Year Additions Charged Against Operations/Recovery Uncollectible Accounts Written-off (1) Balance at End of Year Year Ended December 31, 2017 Tenant and other receivables—allowance $ 4,879 $ 3,657 $ (1,299 ) $ 7,237 Deferred rent receivable—allowance 17,798 2,084 (8,693 ) 11,189 Year Ended December 31, 2016 Tenant and other receivables—allowance $ 5,593 $ 3,604 $ (4,318 ) $ 4,879 Deferred rent receivable—allowance 14,788 3,955 (945 ) 17,798 Year Ended December 31, 2015 Tenant and other receivables—allowance $ 5,820 $ 4,363 $ (4,590 ) $ 5,593 Deferred rent receivable—allowance 17,745 1,775 (4,732 ) 14,788 (1) Includes the effect of properties that were sold and/or deconsolidated within the period.

Schedule III_Real Estate And Ac

Schedule III—Real Estate And Accumulated Depreciation	12 Months Ended
	Dec. 31, 2017
SEC Schedule III, Real Estate and Accumulated Depreciation Disclosure [Abstract]
Schedule III—Real Estate And Accumulated Depreciation	Schedule III—Real Estate And Accumulated Depreciation December 31, 2017 (in thousands) Column A Column B Column C Initial Cost Column D Cost Capitalized Subsequent To Acquisition Column E Gross Amount at Which Carried at Close of Period Column F Column G Column H Column I Description Encumbrances Land Building & Improvements Land Building & Improvements Land Building & Improvements Total Accumulated Depreciation Date of Construction Date Acquired Life on Which Depreciation is Computed 810 Seventh Avenue(1) $ — $ 114,077 $ 476,386 $ — $ 71,735 $ 114,077 $ 548,121 $ 662,198 $ 162,606 1970 1/2007 Various 461 Fifth Avenue(1) — — 62,695 — 16,185 — 78,880 78,880 28,378 1988 10/2003 Various 750 Third Avenue(1) — 51,093 205,972 — 42,543 51,093 248,515 299,608 93,469 1958 7/2004 Various 919 Third Avenue(1)(2) 500,000 223,529 1,033,198 — 65,089 223,529 1,098,287 1,321,816 303,424 1970 1/2007 Various 555 W. 57th Street(1) — 18,846 78,704 — 61,424 18,846 140,128 158,974 64,281 1971 1/1999 Various 1185 Avenue of the Americas(1) — — 728,213 — 47,793 — 776,006 776,006 242,681 1969 1/2007 Various 1350 Avenue of the Americas(1) — 91,038 380,744 (97 ) 41,911 90,941 422,655 513,596 124,638 1966 1/2007 Various 100 Summit Lake Drive(3) — 10,526 43,109 — 11,215 10,526 54,324 64,850 16,963 1988 1/2007 Various 200 Summit Lake Drive(3) — 11,183 47,906 — 11,177 11,183 59,083 70,266 18,818 1990 1/2007 Various 500 Summit Lake Drive(3) — 9,777 39,048 — 6,358 9,777 45,406 55,183 13,074 1986 1/2007 Various 360 Hamilton Avenue(3) — 29,497 118,250 — 15,392 29,497 133,642 163,139 39,811 2000 1/2007 Various 1010 Washington Boulevard(4) — 7,747 30,423 — 7,378 7,747 37,801 45,548 11,044 1988 1/2007 Various 1055 Washington Boulevard(4) — 13,516 53,228 — 8,390 13,516 61,618 75,134 18,075 1987 6/2007 Various 400 Summit Lake Drive(3) — 38,889 1 285 3 39,174 4 39,178 — - 1/2007 N/A 609 Fifth Avenue(1) — 36,677 145,954 — 10,435 36,677 156,389 193,066 46,059 1925 6/2006 Various 110 East 42nd Street(1) — 34,000 46,411 (138 ) 23,984 33,862 70,395 104,257 17,244 1921 5/2011 Various 304 Park Avenue(1) — 54,189 75,619 300 14,550 54,489 90,169 144,658 16,445 1930 6/2012 Various 635 Sixth Avenue(1) — 24,180 37,158 163 51,805 24,343 88,963 113,306 7,854 1902 9/2012 Various 641 Sixth Avenue(1) — 45,668 67,316 308 6,029 45,976 73,345 119,321 12,097 1902 9/2012 Various 315 West 33rd Street(1) 250,000 195,834 164,429 — 11,583 195,834 176,012 371,846 19,966 2000-2001 11/2013 Various Williamsburg(6)(7) — 3,677 14,708 2,523 (4,550 ) 6,200 10,158 16,358 1,865 2010 12/2010 Various 115 Spring Street(1) — 11,078 44,799 — 1,759 11,078 46,558 57,636 4,083 1900 7/2014 Various 635 Madison Avenue(1) — 205,632 15,805 — — 205,632 15,805 221,437 1,306 - 9/2014 N/A 125 Park Avenue(1) — 120,900 189,714 — 74,660 120,900 264,374 385,274 65,529 1923 10/2010 Various 625 Madison Ave(1) — — 246,673 — 43,175 — 289,848 289,848 107,791 1956 10/2004 Various 711 Third Avenue(1)(6)(8) — 19,844 42,499 — 66,553 19,844 109,052 128,896 39,396 1955 5/1998 Various 752 Madison Avenue(1)(6)(9) — 282,415 — 1,871 — 284,286 — 284,286 12 1996/2012 1/2012 N/A 110 Greene Street(1)(10) — 45,120 215,470 — 9,611 45,120 225,081 270,201 15,693 1910 7/2015 Various Other(11) — 1,130 — (1,135 ) 4,694 (5 ) 4,694 4,689 1 Various $ 750,000 $ 1,700,062 $ 4,604,432 $ 4,080 $ 720,881 $ 1,704,142 $ 5,325,313 $ 7,029,455 $ 1,492,603 __________________________________________________________________ (1) Property located in New York, New York. (2) We own a 51% interest in this property. (3) Property located in Westchester County, New York. (4) Property located in Connecticut. (5) Property that was transferred in 2015. (6) Property located in Brooklyn, New York. (7) We own a 50% interest in this property. (8) We own a tenancy in common interest in the property. (9) We own a 90% interest in this property. (10) Other includes tenant improvements, capitalized interest and corporate improvements. The changes in real estate for the years ended December 31, 2017 , 2016 and 2015 are as follows (in thousands): 2017 2016 2015 Balance at beginning of year $ 7,508,870 $ 7,428,243 $ 7,203,216 Acquisitions — — 329,996 Improvements 121,959 123,173 93,439 Retirements/disposals (601,374 ) (42,546 ) (198,408 ) Balance at end of year $ 7,029,455 $ 7,508,870 $ 7,428,243 The aggregate cost of land, buildings and improvements, before depreciation, for Federal income tax purposes at December 31, 2017 was approximately $4.6 billion (unaudited). The changes in accumulated depreciation, exclusive of amounts relating to equipment, autos, and furniture and fixtures, for the years ended December 31, 2017 , 2016 and 2015 , are as follows (in thousands): 2017 2016 2015 Balance at beginning of year $ 1,437,222 $ 1,267,598 $ 1,123,412 Depreciation for year 178,801 183,873 175,039 Retirements/disposals (123,420 ) (14,249 ) (30,853 ) Balance at end of year $ 1,492,603 $ 1,437,222 $ 1,267,598

Significant Accounting Polici29

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include our accounts and those of our subsidiaries, which are wholly-owned or controlled by us. Entities which we do not control through our voting interest and entities which are variable interest entities, but where we are not the primary beneficiary, are accounted for under the equity method. See Note 5, "Debt and Preferred Equity Investments" and Note 6, "Investments in Unconsolidated Joint Ventures." All significant intercompany balances and transactions have been eliminated. We consolidate a variable interest entity, or VIE, in which we are considered the primary beneficiary. The primary beneficiary 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. A noncontrolling interest in a consolidated subsidiary is defined as the portion of the equity (net assets) in a subsidiary not attributable, directly or indirectly, to us. Noncontrolling interests are required to be presented as a separate component of equity in the consolidated balance sheet and the presentation of net income is modified to present earnings and other comprehensive income attributed to controlling and noncontrolling interests. We assess the accounting treatment for each joint venture and debt and preferred equity investment. This assessment includes a review of each joint venture or limited liability company agreement to determine the rights provided to each party and whether those rights are protective or participating. For all VIEs, we 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. In situations where we and our partner approve, among other things, the annual budget, receive a detailed monthly reporting package, meet on a quarterly basis to review the results of the joint venture, review and approve the joint venture's tax return before filing, and approve all leases that cover more than a nominal amount of space relative to the total rentable space at each property, we do not consolidate the joint venture as we consider these to be substantive participation rights that result in shared power of the activities that most significantly impact the performance of the joint venture. Our joint venture agreements typically contain certain protective rights such as requiring partner approval to sell, finance or refinance the property and the payment of capital expenditures and operating expenditures outside of the approved budget or operating plan. In January 2018, the partnership agreement for our investment in the property at 919 Third Avenue was modified resulting in our partner now having substantive participating rights in the venture. As a result the investment will no longer be deemed a VIE and our investment in the property will be deconsolidated as of January 1, 2018. The Company will record its non-controlling interest at fair value. This fair value will be allocated to the assets and liabilities, including identified intangibles. Under this methodology, the leases are ascribed an in-place lease intangible value as well as an above or below market lease intangible value which will be amortized over the remaining term of the associated leases.
Investment in Commercial Real Estate Properties	Investment in Commercial Real Estate Properties Real estate properties are presented at cost less accumulated depreciation and amortization. Costs directly related to the development or redevelopment of properties are capitalized. Ordinary repairs and maintenance are expensed as incurred; major replacements and betterments, which improve or extend the life of the asset, are capitalized and depreciated over their estimated useful lives. We recognize the assets acquired, liabilities assumed (including contingencies) and any noncontrolling interests in an acquired entity at their respective fair values on the acquisition date. When we acquire our partner's equity interest in an existing unconsolidated joint venture and gain control over the investment, we record the consolidated investment at fair value. The difference between the book value of our equity investment on the purchase date and our share of the fair value of the investment's purchase price is recorded as a purchase price fair value adjustment in our consolidated statements of operations. See Note 3, "Property Acquisitions." We allocate the purchase price of real estate to land and building (inclusive of tenant improvements) and, if determined to be material, intangibles, such as the value of above- and below-market leases and origination costs associated with the in-place leases. We depreciate the amount allocated to building (inclusive of tenant improvements) over their estimated useful lives, which generally range from three to 40 years . We amortize the amount allocated to the above- and below-market leases over the remaining term of the associated lease, which generally range from one to 14 years , and record it as either an increase (in the case of below-market leases) or a decrease (in the case of above-market leases) to rental income. We amortize the amount allocated to the values associated with in-place leases over the expected term of the associated lease, which generally ranges from one to 14 years . If a tenant vacates its space prior to the contractual termination of the lease and no rental payments are being made on the lease, any unamortized balance of the related intangible will be written off. The tenant improvements and origination costs are amortized as an expense over the remaining life of the lease (or charged against earnings if the lease is terminated prior to its contractual expiration date). We assess fair value of the leases based on estimated cash flow projections that utilize appropriate discount and capitalization rates and available market information. Estimates of future cash flows are based on a number of factors including the historical operating results, known trends, and market/economic conditions that may affect the property. To the extent acquired leases contain fixed rate renewal options that are below-market and determined to be material, we amortize such below-market lease value into rental income over the renewal period. As of December 31, 2017 , the weighted average amortization period for above-market leases, below-market leases, and in-place lease costs is 4.4 years, 24.4 years, and 18.1 years, respectively. We incur a variety of costs in the development and leasing of our properties. After the determination is made to capitalize a cost, it is allocated to the specific component of a project that is benefited. Determination of when a development project is substantially complete and capitalization must cease involves a degree of judgment. The costs of land and building under development include specifically identifiable costs. The capitalized costs include, but are not limited to, pre-construction costs essential to the development of the property, development costs, construction costs, interest costs, real estate taxes, salaries and related costs and other costs incurred during the period of development. We consider a construction project as substantially completed and held available for occupancy upon the completion of tenant improvements, but no later than one year after major construction activity ceases. We cease capitalization on the portions substantially completed and occupied or held available for occupancy, and capitalize only those costs associated with the portions under construction. Properties are depreciated using the straight-line method over the estimated useful lives of the assets. On a periodic basis, we assess whether there are any indications that the value of our real estate properties may be other than temporarily impaired or that their carrying value may not be recoverable. A property's value is considered impaired if management's estimate of the aggregate future cash flows (undiscounted) to be generated by the property is less than the carrying value of the property. To the extent impairment has occurred, the loss will be measured as the excess of the carrying amount of the property over the calculated fair value of the property. We also evaluate our real estate properties for impairment when a property has been classified as held for sale. Real estate assets held for sale are valued at the lower of their carrying value or fair value less costs to sell and depreciation expense is no longer recorded.
Cash and Cash Equivalents	Cash and Cash Equivalents We consider all highly liquid investments with maturity of three months or less when purchased to be cash equivalents.
Restricted Cash	Restricted Cash Restricted cash primarily consists of security deposits held on behalf of our tenants, interest reserves, as well as capital improvement and real estate tax escrows required under certain loan agreements.
Investment in Unconsolidated Joint Ventures	Investments in Unconsolidated Joint Ventures We account for our investments in unconsolidated joint ventures under the equity method of accounting in cases where we exercise significant influence over, but do not control, these entities and are not considered to be the primary beneficiary. We consolidate those joint ventures that we control or which are VIEs and where we are considered to be the primary beneficiary. In all these joint ventures, the rights of the joint venture partner are both protective as well as participating. Unless we are determined to be the primary beneficiary in a VIE, these participating rights preclude us from consolidating these VIE entities. These investments are recorded initially at cost, as investments in unconsolidated joint ventures, and subsequently adjusted for equity in net income (loss) and cash contributions and distributions. Equity in net income (loss) from unconsolidated joint ventures is allocated based on our ownership or economic interest in each joint venture. When a capital event (as defined in each joint venture agreement) such as a refinancing occurs, if return thresholds are met, future equity income will be allocated at our increased economic interest. We recognize incentive income from unconsolidated real estate joint ventures as income to the extent it is earned and not subject to a clawback feature. Distributions we receive from unconsolidated real estate joint ventures in excess of our basis in the investment are recorded as offsets to our investment balance if we remain liable for future obligations of the joint venture or may otherwise be committed to provide future additional financial support. None of the joint venture debt is recourse to us. See Note 6, "Investments in Unconsolidated Joint Ventures." We assess our investments in unconsolidated joint ventures for recoverability, and if it is determined that a loss in value of the investment is other than temporary, we write down the investment to its fair value. We evaluate our equity investments for impairment based on the joint ventures' projected discounted cash flows. We do not believe that the values of any of our equity investments were impaired at December 31, 2017 . We may originate loans for real estate acquisition, development and construction, where we expect to receive some of the residual profit from such projects. When the risk and rewards of these arrangements are essentially the same as an investor or joint venture partner, we account for these arrangements as real estate investments under the equity method of accounting for investments. Otherwise, we account for these arrangements consistent with the accounting for our debt and preferred equity investments.
Deferred Lease Costs	Deferred Lease Costs Deferred lease costs consist of fees and direct costs incurred to execute operating leases and are amortized on a straight-line basis over the related lease term.
Deferred Financing Costs	Deferred Financing Costs Deferred financing costs represent commitment fees, legal, title and other third party costs associated with obtaining commitments for financing which result in a closing of such financing. These costs are amortized over the terms of the respective agreements. Unamortized deferred financing costs are expensed when the associated debt is refinanced or repaid before maturity. Costs incurred in seeking financing transactions, which do not close, are expensed in the period in which it is determined that the financing will not close. Deferred debt issuance costs related to a recognized debt liability are presented in the balance sheet as a direct deduction from the carrying amount of that debt liability.
Revenue Recognition	We record a gain on sale of real estate when title is conveyed to the buyer, subject to the buyer's financial commitment being sufficient to provide economic substance to the sale and provided that we have no substantial economic involvement with the buyer. Interest income on debt and preferred equity investments is accrued based on the contractual terms of the instruments and when, in the opinion of management, it is deemed collectible. Some debt and preferred equity investments provide for accrual of interest at specified rates, which differ from current payment terms. Interest is recognized on such loans at the accrual rate subject to management's determination that accrued interest is ultimately collectible, based on the underlying collateral and operations of the borrower. If management cannot make this determination, interest income above the current pay rate is recognized only upon actual receipt. Deferred origination fees, original issue discounts and loan origination costs, if any, are recognized as an adjustment to interest income over the terms of the related investments using the effective interest method. Fees received in connection with loan commitments are also deferred until the loan is funded and are then recognized over the term of the loan as an adjustment to yield. Discounts or premiums associated with the purchase of loans are amortized or accreted into interest income as a yield adjustment on the effective interest method based on expected cash flows through the expected maturity date of the related investment. If we purchase a debt or preferred equity investment at a discount, intend to hold it until maturity and expect to recover the full value of the investment, we accrete the discount into income as an adjustment to yield over the term of the investment. If we purchase a debt or preferred equity investment at a discount with the intention of foreclosing on the collateral, we do not accrete the discount. For debt investments acquired at a discount for credit quality, the difference between contractual cash flows and expected cash flows at acquisition is not accreted. Anticipated exit fees, the collection of which is expected, are also recognized over the term of the loan as an adjustment to yield. Debt and preferred equity investments are placed on a non-accrual status at the earlier of the date at which payments become 90 days past due or when, in the opinion of management, a full recovery of interest income becomes doubtful. Interest income recognition on any non-accrual debt or preferred equity investment is resumed when such non-accrual debt or preferred equity investment becomes contractually current and performance is demonstrated to be resumed. Interest is recorded as income on impaired loans only to the extent cash is received. We may syndicate a portion of the loans that we originate or sell the loans individually. When a transaction meets the criteria for sale accounting, we derecognize the loan sold and recognize gain or loss based on the difference between the sales price and the carrying value of the loan sold. Any related unamortized deferred origination fees, original issue discounts, loan origination costs, discounts or premiums at the time of sale are recognized as an adjustment to the gain or loss on sale, which is included in investment income on the consolidated statement of operations. Any fees received at the time of sale or syndication are recognized as part of investment income. Asset management fees are recognized on a straight-line basis over the term of the asset management agreement. Revenue Recognition Rental revenue is recognized on a straight-line basis over the term of the lease. Rental revenue recognition commences when the tenant takes possession or controls the physical use of the leased space. In order for the tenant to take possession, the leased space must be substantially ready for its intended use. To determine whether the leased space is substantially ready for its intended use, management evaluates whether we are or the tenant is the owner of tenant improvements for accounting purposes. When management concludes that we are the owner of tenant improvements, rental revenue recognition begins when the tenant takes possession of the finished space, which is when such tenant improvements are substantially complete. In certain instances, when management concludes that we are not the owner (the tenant is the owner) of tenant improvements, rental revenue recognition begins when the tenant takes possession of or controls the space. When management concludes that we are the owner of tenant improvements for accounting purposes, we record amounts funded to construct the tenant improvements as a capital asset. For these tenant improvements, we record amounts reimbursed by tenants as a reduction of the capital asset. When management concludes that the tenant is the owner of tenant improvements for accounting purposes, we record our contribution towards those improvements as a lease incentive, which is included in deferred costs, net on our consolidated balance sheets and amortized as a reduction to rental revenue on a straight-line basis over the term of the lease. The excess of rents recognized over amounts contractually due pursuant to the underlying leases are included in deferred rents receivable on the consolidated balance sheets. We establish, on a current basis, an allowance for future potential tenant credit losses, which may occur against this account. The balance reflected on the consolidated balance sheets is net of such allowance. In addition to base rent, our tenants also generally will pay their pro rata share of increases in real estate taxes and operating expenses for the building over a base year. In some leases, in lieu of paying additional rent based upon increases in building operating expenses, the tenant will pay additional rent based upon increases in the wage rate paid to porters over the porters' wage rate in effect during a base year or increases in the consumer price index over the index value in effect during a base year. In addition, many of our leases contain fixed percentage increases over the base rent to cover escalations. Electricity is most often supplied by the landlord either on a sub-metered basis, or rent inclusion basis (i.e., a fixed fee is included in the rent for electricity, which amount may increase based upon increases in electricity rates or increases in electrical usage by the tenant). Base building services other than electricity (such as heat, air conditioning and freight elevator service during business hours, and base building cleaning) are typically provided at no additional cost, with the tenant paying additional rent only for services which exceed base building services or for services which are provided outside normal business hours. These escalations are based on actual expenses incurred in the prior calendar year. If the expenses in the current year are different from those in the prior year, then during the current year, the escalations will be adjusted to reflect the actual expenses for the current year.
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts We maintain an allowance for doubtful accounts for estimated losses resulting from the inability of our tenants to make required payments. If the financial condition of a specific tenant were to deteriorate, resulting in an impairment of its ability to make payments, additional allowances may be required.
Reserve for Possible Credit Losses	Reserve for Possible Credit Losses The expense for possible credit losses in connection with debt and preferred equity investments is the charge to earnings to increase the allowance for possible credit losses to the level that we estimate to be adequate, based on Level 3 data, considering delinquencies, loss experience and collateral quality. Other factors considered include geographic trends, product diversification, the size of the portfolio and current economic conditions. Based upon these factors, we establish a provision for possible credit loss on each individual investment. When it is probable that we will be unable to collect all amounts contractually due, the investment is considered impaired. Where impairment is indicated on an investment that is held to maturity, a valuation allowance is measured based upon the excess of the recorded investment amount over the fair value of the collateral. Any deficiency between the carrying amount of an asset and the calculated value of the collateral is charged to expense. We continue to assess or adjust our estimates based on circumstances of a loan and the underlying collateral. If additional information reflects increased recovery of our investment, we will adjust our reserves accordingly. There were no loan reserves recorded during the years ended December 31, 2017 , 2016 , and 2015 . Debt and preferred equity investments held for sale are carried at the lower of cost or fair market value using available market information obtained through consultation with dealers or other originators of such investments as well as discounted cash flow models based on Level 3 data pursuant to ASC 820-10. As circumstances change, management may conclude not to sell an investment designated as held for sale. In such situations, the investment will be reclassified at its net carrying value to debt and preferred equity investments held to maturity. For these reclassified investments, the difference between the current carrying value and the expected cash to be collected at maturity will be accreted into income over the remaining term of the investment.
Rent Expense	Rent Expense Rent expense is recognized on a straight-line basis over the initial term of the lease. The excess of the rent expense recognized over the amounts contractually due pursuant to the underlying lease is included in the deferred lease payable on the consolidated balance sheets.
Exchangeable Debt Instruments	Exchangeable Debt Instruments The initial proceeds from exchangeable debt that may be settled in cash, including partial cash settlements, are bifurcated between a liability component and an equity component associated with the embedded conversion option. The objective of the accounting guidance is to require the liability and equity components of exchangeable debt to be separately accounted for in a manner such that the interest expense on the exchangeable debt is not recorded at the stated rate of interest but rather at an effective rate that reflects the issuer's conventional debt borrowing rate at the date of issuance. We calculate the liability component of exchangeable debt based on the present value of the contractual cash flows discounted at our comparable market conventional debt borrowing rate at the date of issuance. The difference between the principal amount and the fair value of the liability component is reported as a discount on the exchangeable debt that is accreted as additional interest expense from the issuance date through the contractual maturity date using the effective interest method. A portion of this additional interest expense may be capitalized to the development and redevelopment balances qualifying for interest capitalization each period. The liability component of the exchangeable debt is reported net of discounts on our consolidated balance sheets. We calculate the equity component of exchangeable debt based on the difference between the initial proceeds received from the issuance of the exchangeable debt and the fair value of the liability component at the issuance date. The equity component is included in additional paid-in-capital, net of issuance costs, on our consolidated balance sheets. We allocate issuance costs for exchangeable debt between the liability and the equity components based on their relative values.
Income Taxes	Income Taxes SL Green is taxed as a REIT under Section 856(c) of the Code. As a REIT, SL Green generally is not subject to Federal income tax. To maintain its qualification as a REIT, SL Green must distribute at least 90% of its REIT taxable income to its stockholders and meet certain other requirements. If SL Green fails to qualify as a REIT in any taxable year, SL Green will be subject to Federal income tax on its taxable income at regular corporate rates. SL Green may also be subject to certain state, local and franchise taxes. Under certain circumstances, Federal income and excise taxes may be due on its undistributed taxable income. ROP is a disregarded entity of SL Green Operating Partnership, L.P. for federal income tax purposes, and, as a result, all income and losses of ROP are considered income and losses of SL Green Operating Partnership, L. P. No provision has been made for income taxes in the consolidated financial statements since such taxes, if any, are the responsibility of the individual partners of SL Green Operating Partnership, L.P. We follow a two-step approach for evaluating uncertain tax positions. Recognition (step one) occurs when an enterprise concludes that a tax position, based solely on its technical merits, is more-likely-than-not to be sustained upon examination. Measurement (step two) determines the amount of benefit that is more-likely-than-not to be realized upon settlement. Derecognition of a tax position that was previously recognized would occur when a company subsequently determines that a tax position no longer meets the more-likely-than-not threshold of being sustained. The use of a valuation allowance as a substitute for derecognition of tax positions is prohibited. On December 22, 2017, the Tax Cuts and Jobs Act (the ‘‘Tax Act’’) was signed into law and makes substantial changes to the Code. Many of the provisions of the Tax Act will require guidance through the issuance of Treasury regulations in order to assess their effect. The Tax Act did not have a material impact on our financial statements for the year ended December, 31, 2017.
Derivative Instruments	Derivative Instruments In the normal course of business, we use a variety of commonly used derivative instruments, such as interest rate swaps, caps, collars and floors, to manage, or hedge, interest rate risk. Effectiveness is essential for those derivatives that we intend to qualify for hedge accounting. Some derivative instruments are associated with an anticipated transaction. In those cases, hedge effectiveness criteria also require that it be probable that the underlying transaction occurs. Instruments that meet these hedging criteria are formally designated as hedges at the inception of the derivative contract. To determine the fair values of derivative instruments, we use a variety of methods and assumptions that are based on market conditions and risks existing at each balance sheet date. For the majority of financial instruments including most derivatives, long-term investments and long-term debt, standard market conventions and techniques such as discounted cash flow analysis, option pricing models, replacement cost, and termination cost are used to determine fair value. All methods of assessing fair value result in a general approximation of value, and such value may never actually be realized. In the normal course of business, we are exposed to the effect of interest rate changes and limit these risks by following established risk management policies and procedures including the use of derivatives. To address exposure to interest rates, derivatives are used primarily to fix the rate on debt based on floating-rate indices and manage the cost of borrowing obligations. We use a variety of conventional derivative products. These derivatives typically include interest rate swaps, caps, collars and floors. We expressly prohibit the use of unconventional derivative instruments and using derivative instruments for trading or speculative purposes. Further, we have a policy of only entering into contracts with major financial institutions based upon their credit ratings and other factors. We may employ swaps, forwards or purchased options to hedge qualifying forecasted transactions. Gains and losses related to these transactions are deferred and recognized in net income as interest expense in the same period or periods that the underlying transaction occurs, expires or is otherwise terminated. Hedges that are reported at fair value and presented on the balance sheet could be characterized as cash flow hedges or fair value hedges. Interest rate caps and collars are examples of cash flow hedges. Cash flow hedges address the risk associated with future cash flows of interest payments. For all hedges held by us and which were deemed to be fully effective in meeting the hedging objectives established by our corporate policy governing interest rate risk management, no net gains or losses were reported in earnings. The changes in fair value of hedge instruments are reflected in accumulated other comprehensive income. For derivative instruments not designated as hedging instruments, the gain or loss, resulting from the change in the estimated fair value of the derivative instruments, is recognized in current earnings during the period of change.
Shares Contributed by Parent Company	Shares Contributed by Parent Company We present shares of SL Green common stock as a contra-equity account in our financial statements.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates.
Concentrations of Credit Risk	Concentrations of Credit Risk Financial instruments that potentially subject us to concentrations of credit risk consist primarily of cash investments, debt and preferred equity investments and accounts receivable. We place our cash investments in excess of insured amounts with high quality financial institutions. The collateral securing our debt and preferred equity investments is located in the New York metropolitan area. See Note 5, "Debt and Preferred Equity Investments." We perform ongoing credit evaluations of our tenants and require most tenants to provide security deposits or letters of credit. Though these security deposits and letters of credit are insufficient to meet the total value of a tenant's lease obligation, they are a measure of good faith and a source of funds to offset the economic costs associated with lost revenue and the costs associated with re-tenanting a space. The properties in our real estate portfolio are primarily located in Manhattan, we also have properties located in Brooklyn, and Westchester County, Connecticut. The tenants located in our buildings operate in various industries.
Reclassification	Reclassification Certain prior year balances have been reclassified to conform to our current year presentation
Accounting Standards Updates	Accounting Standards Updates In August 2017, the FASB issued Accounting Standards Update (ASU) No. 2017-12, Derivatives and Hedging (Topic 815), Targeted Improvements to Accounting for Hedging Activities. The amendments in the new standard will permit more flexibility in hedging interest rate risk for both variable rate and fixed rate financial instruments. The standard will also enhance the presentation of hedge results in the financial statements. The guidance is effective for fiscal years beginning after December 15, 2018 and early adoption is permitted. The Company has not yet adopted the guidance, and does not expect a material impact on the Company’s consolidated financial statements when the new standard is implemented. In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business. The guidance clarifies the definition of a business and provides guidance to assist with determining whether transactions should be accounted for as acquisitions of assets or businesses. The main provision is that an acquiree is not a business if substantially all of the fair value of the gross assets is concentrated in a single identifiable asset or group of assets. The Company adopted the guidance on the issuance date effective January 5, 2017. The Company expects that most of its real estate acquisitions will be considered asset acquisitions under the new guidance and that transaction costs will be capitalized to the investment basis which is then subject to a purchase price allocation based on relative fair value. In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. The guidance will require entities to show the changes on the total cash, cash equivalents, restricted cash and restricted cash equivalents in the statement of cash flows. As a result, entities will no longer present transfers between these items on the statement of cash flows. The guidance is effective for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Early adoption is permitted. The Company has not yet adopted this new guidance and is currently evaluating the impact of adopting this new accounting standard on the Company’s consolidated financial statements. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. The ASU provides final guidance on eight cash flow issues, including debt prepayment or debt extinguishment costs, contingent consideration payments made after a business combination, distributions received from equity method investees, separately identifiable cash flows and application of the predominance principle, and others. The amendments in the ASU are effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The Company adopted the guidance effective January 1, 2017 and there was no impact on the Company’s consolidated financial statements. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The guidance changes how entities will measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. The guidance replaces the current ‘incurred loss’ model with an ‘expected loss’ approach. The guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted after December 2018. The Company has not yet adopted this new guidance and is currently evaluating the impact of adopting this new accounting standard on the Company’s consolidated financial statements. In March 2016, the FASB issued ASU 2016-07, Investments Equity Method and Joint Ventures (Topic 323). The guidance eliminates the requirement that an entity retroactively adopt the equity method of accounting if an investment qualifies for use of the equity method as a result of an increase in the level of ownership or degree of influence. The amendments require that the equity method investor add the cost of acquiring the additional interest in the investee to the current basis of the investor’s previously held interest and adopt the equity method of accounting as of the date the investment becomes qualified for equity method accounting. The Company adopted the guidance effective January 1, 2017 and there was no impact on the Company’s consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, Leases. The guidance requires lessees to recognize lease assets and lease liabilities for those leases classified as operating leases under the previous standard. Depending on the lease classification, lessees will recognize expense based on the effective interest method for finance leases or on a straight-line basis for operating leases. The accounting applied by a lessor is largely unchanged from that applied under the previous standard. One of the potential impacts on the Company may be the presentation and disclosure in the financial statements of non-lease components such as charges to tenants for a building’s operating expenses. As currently written, the guidance would require that the non-lease components be presented separately from the lease components in both the Consolidated Statements of Operations and Consolidated Balance Sheets. In January 2018, the FASB issued an exposure draft, Leases (Topic 842) Targeted Improvements, which would provide lessors with a practical expedient to not separate non-lease components from the related lease component under certain conditions. We anticipate the majority of our leases would qualify for the practical expedient. We expect this guidance to be finalized in 2018 and, as a result, we would adopt the practical expedient. Another impact is the measurement and presentation of ground leases under which the Company is lessee. The Company is required to record a liability for the obligation to make payments under the lease and an asset for the right to use the underlying asset during the lease term and will also apply the new expense recognition requirements given the lease classification. The Company is currently quantifying these impacts. The guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. The Company expects to adopt this guidance January 1, 2019 and will apply the modified retrospective approach. In January 2016, the FASB issued ASU 2016-01 (Subtopic 825-10), Recognition and Measurement of Financial Assets and Financial Liabilities. The guidance requires entities to measure equity investments that do not result in consolidation and are not accounted for under the equity method at fair value through earnings to record changes in instruments-specific credit risk for financial liabilities measured under the fair value option in other comprehensive income, use the exit price notion when measuring an instrument’s fair value for disclosure and to separately present financial assets and liabilities by measurement category and form of instrument on the balance sheet or in the notes to the financial statements. The guidance is effective for fiscal years beginning after December 15, 2017, and for interim periods therein. The Company has not yet adopted this new guidance and does not expect a material impact on the Company’s consolidated financial statements when the new standard is implemented. In May 2014, the FASB issued a new comprehensive revenue recognition guidance which requires us to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which we expect to be entitled in exchange for those goods and services (ASU 2014-09). The FASB also issued implementation guidance in March 2016, April 2016 and May 2016 - ASU’s 2016-08, 2016-10 and 2016-12, respectively. These ASUs are effective for annual and interim periods beginning after December 15, 2017. The Company will adopt this guidance January 1, 2018. Since the Company’s revenue is related to leasing activities, the adoption of this guidance will not have a material impact on the consolidated financial statements. The new guidance is applicable to service contracts with joint ventures for which the Company earns property management fees, leasing commissions and development and construction fees. The adoption of this new guidance does not change the accounting for these fees as the pattern of recognition of revenue does not change with the new guidance. We will continue to recognize revenue over time on these contracts because the customer simultaneously receives and consumes the benefits provided by our performance. Thus, the analysis of our contracts under the new revenue recognition standard is consistent with our current revenue recognition model. In February 2017, the FASB issued Accounting Standards Update (ASU) No. 2017-05 to clarify the scope of asset derecognition guidance in Subtopic 610-20, which also provided guidance on accounting for partial sales of nonfinancial assets and requires any retained non-controlling interest to be recorded at fair value. Subtopic 610-20 was issued in May 2014 as part of ASU 2014-09. The Company will elect to adopt the practical expedient under ASC 606, Revenue from Contracts with Customers, which allows an entity to apply the guidance to contracts with non-customers that are open based on the ASC 360-20, Real Estate Sales, (i.e. failed sales) as of the adoption date. The Company will adopt this guidance January 1, 2018, and does not expect a material impact on the consolidated financial statements as the Company had no open contracts based on ASC 360-20 as of December 31, 2017.
Fair Value Measurements	Fair Value Measurements We are required to disclose fair value information with regard to our financial instruments, whether or not recognized in the consolidated balance sheets, for which it is practical to estimate fair value. The FASB guidance defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants on the measurement date. We measure and/or disclose the estimated fair value of financial assets and liabilities based on a hierarchy that distinguishes between market participant assumptions based on market data obtained from sources independent of the reporting entity and the reporting entity’s own assumptions about market participant assumptions. This hierarchy consists of three broad levels: Level 1 - quoted prices (unadjusted) in active markets for identical assets or liabilities that the reporting entity can access at the measurement date; Level 2 - inputs other than quoted prices included within Level 1, that are observable for the asset or liability, either directly or indirectly; and Level 3 - unobservable inputs for the asset or liability that are used when little or no market data is available. We follow this hierarchy for our assets and liabilities measured at fair value on a recurring and nonrecurring basis. In instances in which the determination of the fair value measurement is based on inputs from different levels of the fair value hierarchy, the level in the fair value hierarchy within which the entire fair value measurement falls is based on the lowest level of input that is significant to the fair value measurement in its entirety. Our assessment of the significance of the particular input to the fair value measurement in its entirety requires judgment and considers factors specific to the asset or liability. The following tables set forth the assets and liabilities that we measure at fair value on a recurring and non-recurring basis by their levels in the fair value hierarchy at December 31, 2017 and 2016 (in thousands): December 31, 2017 Total Level 1 Level 2 Level 3 Assets: Interest rate cap and swap agreements (included in other assets) $ 167 $ — $ 167 $ — December 31, 2016 Total Level 1 Level 2 Level 3 Assets: Interest rate cap and swap agreements (included in other assets) $ — $ — $ — $ — We determine other than temporary impairment in real estate investments and debt and preferred equity investments, including intangibles primarily utilizing cash flow projections that apply, among other things, estimated revenue and expense growth rates, discount rates and capitalization rates, as well as sales comparison approach, which utilizes comparable sales, listings and sales contracts. All of which are classified as Level 3 inputs. As of December 31, 2017 , we held notes receivable totaling $250.0 million , which were purchased at par, and were in maturity default at the time of acquisition. In August 2017, the Company determined that it was probable that the loans would not be repaid in full and therefore, the loans were put on non-accrual status. The loans had an outstanding balance including accrued interest of $259.3 million at the time that they were put on non accrual status. The Company has initiated proceedings to foreclose on the property, and expects to take control of the property unless the buyer is able to repay the principal and interest, including default interest and fees, on the notes receivable in full prior to the completion of the foreclosure process. We believe the collateral value is sufficient to recover the carrying amounts of the notes receivable. The fair value of derivative instruments is based on current market data received from financial sources that trade such instruments and are based on prevailing market data and derived from third party proprietary models based on well-recognized financial principles and reasonable estimates about relevant future market conditions, which are classified as Level 2 inputs. The financial assets and liabilities that are not measured at fair value on our consolidated balance sheets include cash and cash equivalents, restricted cash, accounts receivable, accounts payable and accrued expenses, debt and preferred equity investments, mortgages and other loans payable and other secured and unsecured debt. The carrying amount of cash and cash equivalents, restricted cash, accounts receivable, and accounts payable and accrued expenses reported in our consolidated balance sheets approximates fair value due to the short term nature of these instruments. The fair value of debt and preferred equity investments, which is classified as Level 3, is estimated by discounting the future cash flows using current interest rates at which similar loans with the same maturities would be made to borrowers with similar credit ratings. The fair value of borrowings, which is classified as Level 3, is estimated by discounting the contractual cash flows of each debt instrument to their present value using adjusted market interest rates, which is provided by a third-party specialist.

Organization and Basis of Pre30

Organization and Basis of Presentation (Tables)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of commercial office properties	As of December 31, 2017 , we owned the following interests in properties in the New York metropolitan area, primarily in midtown Manhattan. Our investments located outside of Manhattan are referred to as the Suburban properties: Location Type Number of Properties Approximate Square Feet (unaudited) Weighted Average (1) (unaudited) Commercial: Manhattan Office 16 8,463,245 95.9 % Retail (2)(3) 5 364,816 98.0 % Fee Interest 1 176,530 100.0 % 22 9,004,591 96.0 % Suburban Office (4) 13 2,150,400 85.5 % Retail 1 52,000 100.0 % 14 2,202,400 85.9 % Total commercial properties 36 11,206,991 94.0 % Residential: Manhattan Residential (2) — 222,855 85.9 % Total portfolio 36 11,429,846 93.9 % ____________________________________________________________________ (1) The weighted average occupancy for commercial properties represents the total occupied square feet divided by total square footage at acquisition. The weighted average occupancy for residential properties represents the total occupied units divided by total available units. (2) As of December 31, 2017 , we owned a building that was comprised of approximately 270,132 square feet (unaudited) of retail space and approximately 222,855 square feet (unaudited) of residential space. For the purpose of this report, we have included the building in the number of retail properties we own. However, we have included only the retail square footage in the retail approximate square footage, and have listed the balance of the square footage as residential square footage. (3) Includes two unconsolidated joint venture retail properties at 131-137 Spring Street comprised of approximately 68,342 square feet (unaudited). (4) Includes the properties at 115-117 Stevens Avenue in Valhalla, New York, and 1-6 International Drive in Rye Brook, New York which were classified as held for sale at December 31, 2017.

Significant Accounting Polici31

Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Schedule of estimated useful lives	Properties are depreciated using the straight-line method over the estimated useful lives of the assets. The estimated useful lives are as follows: Category Term Building (fee ownership) 40 years Building improvements shorter of remaining life of the building or useful life Building (leasehold interest) lesser of 40 years or remaining term of the lease Property under capital lease remaining lease term Furniture and fixtures four to seven years Tenant improvements shorter of remaining term of the lease or useful life
Summary of identified intangible assets (acquired above-market leases and in-place leases) and intangible liabilities (acquired below-market leases)	The following summarizes our identified intangible assets (acquired above-market leases and in-place leases) and intangible liabilities (acquired below-market leases) as of December 31, 2017 and 2016 (in thousands): December 31, 2017 December 31, 2016 Identified intangible assets (included in other assets): Gross amount $ 276,163 $ 311,830 Accumulated amortization (236,737 ) (253,064 ) Net (1) $ 39,426 $ 58,766 Identified intangible liabilities (included in deferred revenue): Gross amount $ 496,438 $ 524,793 Accumulated amortization (366,091 ) (368,738 ) Net (1) $ 130,347 $ 156,055 (1) As of December 31, 2017, 0.1 million net intangible assets and 0.1 million net intangible liabilities were reclassified to assets held for sale and liabilities related to assets held for sale.
Schedule of estimated annual amortization of acquired below-market leases, net of acquired above-market leases	The estimated annual amortization of acquired above-market leases, net of acquired (below-market) leases (a component of rental revenue), for each of the five succeeding years is as follows (in thousands): 2018 $ (13,620 ) 2019 (13,117 ) 2020 (12,301 ) 2021 (3,815 ) 2022 (3,512 )
Schedule of estimated annual amortization of all other identifiable assets	The estimated annual amortization of all other identifiable assets (a component of depreciation and amortization expense) including tenant improvements for each of the five succeeding years is as follows (in thousands): 2018 $ 8,188 2019 6,641 2020 5,830 2021 2,985 2022 1,423

Property Acquisitions (Tables)

Property Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
Schedule of recognized identified assets acquired and liabilities assumed	During the year ended December 31, 2016, we finalized the purchase price allocation for the following 2015 acquisition based on facts and circumstances that existed at the acquisition date for the property (in thousands): 110 Greene Street (1)(2) Acquisition Date July 2015 Ownership Type Fee Interest Property Type Office Purchase Price Allocation: Land $ 45,120 Building and building leasehold 215,470 Above-market lease value — Acquired in-place leases 8,967 Other assets, net of other liabilities — Assets acquired 269,557 Mark-to-market assumed debt — Below-market lease value (14,557 ) Derivatives — Liabilities assumed (14,557 ) Purchase price $ 255,000 Net consideration funded by us at closing, excluding consideration financed by debt $ 255,000 Equity and/or debt investment held $ — Debt assumed $ — (1) Based on our preliminary analysis of the purchase price, we had allocated $89.3 million and $165.8 million to land and building, respectively, at 110 Greene Street. The impact to our consolidated statements of operations for the twelve months ended December 31, 2016 was an increase in rental revenue of $1.6 million for the amortization of aggregate below-market leases and an additional $3.1 million of depreciation expense. (2) We acquired a 90.0% controlling interest in this property for consideration that included the issuance of $5.0 million and $6.7 million aggregate liquidation preferences of Series P and Q Preferred Units, respectively, of limited partnership interest of the Operating Partnership and cash.

Properties Held for Sale and 33

Properties Held for Sale and Property Dispositions (Tables)	12 Months Ended
	Dec. 31, 2017
Discontinued Operations and Disposal Groups [Abstract]
Schedule of properties sold and income from discontinued operations	The following table summarizes the properties sold during the years ended December 31, 2017 , 2016 and 2015 : Property Disposition Date Property Type (unaudited) Approximate Usable Square Feet Sales Price (1) (in millions) Gain (Loss) on Sale (2) (in millions) 125 Chubb Way (3) October 2017 Office 278,000 $ 29.5 $ (26.1 ) 16 Court Street October 2017 Office 317,600 171.0 64.9 680-750 Washington Boulevard (4) July 2017 Office 325,000 97.0 (44.2 ) 520 White Plains Road (5) April 2017 Office 180,000 21.0 (14.6 ) 102 Greene Street (6) April 2017 Retail 9,200 43.5 4.9 7 International Drive May 2016 Land 31 Acres 20.0 (6.9 ) 140 Grand Street (7) December 2015 Office 130,100 22.4 (10.5 ) 131-137 Spring Street (8) August 2015 Office 68,342 277.8 101.1 (1) Sales price represents the actual sales price for the property or the gross asset valuation for the interest in a property. (2) The gain on sale for 16 Court Street, 102 Greene Street, 131-137 Spring Street are net of $2.5 million , $0.9 million , and $4.1 million , respectively, in employee compensation awards accrued in connection with the realization of these investment gains as a bonus to certain employees that were instrumental in realizing the gain on sale. Additionally, amounts do not include adjustments for expenses recorded in subsequent periods. (3) The Company recorded a $26.1 million charge in 2017 that is included in depreciable real estate reserves in the consolidated statement of operations. (4) The Company recorded a $44.2 million charge in 2017 that is included in depreciable real estate reserves in the consolidated statement of operations. (5) The Company recorded a $14.6 million charge in 2017 that is included in depreciable real estate reserves in the consolidated statement of operations. (6) In April 2017, we closed on the sale of a 90 % interest 102 Greene Street and had subsequently accounted for our interest in the property as an investment in unconsolidated joint ventures. We sold the remaining 10 % interest in September 2017. See Note 6, "Investments in Unconsolidated Joint Ventures." (7) The Company recorded a $10.0 million charge in 2015 that is included in depreciable real estate reserves in the consolidated statement of operations. (8) We sold an 80% interest in 131-137 Spring Street and have subsequently accounted for our interest in the properties as an investment in unconsolidated joint ventures. See Note 6, "Investments in Unconsolidated Joint Ventures."

Debt and Preferred Equity Inv34

Debt and Preferred Equity Investments (Tables)	12 Months Ended
	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Rollforward of debt and preferred equity investments	Below is the rollforward analysis of the activity relating to our debt and preferred equity investments as of December 31, 2017 and 2016 (in thousands): December 31, 2017 December 31, 2016 Balance at beginning of period (1) $ 1,640,412 $ 1,670,020 Debt investment originations/accretion (2) 1,142,591 1,009,176 Preferred Equity investment originations/accretion (2) 144,456 5,698 Redemptions/sales/syndications/amortization (3) (813,418 ) (1,044,482 ) Balance at end of period (1) $ 2,114,041 $ 1,640,412 (1) Net of unamortized fees, discounts, and premiums. (2) Accretion includes amortization of fees and discounts and paid-in-kind investment income. (3) Certain participations in debt investments that were sold or syndicated did not meet the conditions for sale accounting are included in other assets and other liabilities on the consolidated balance sheets
Schedule of debt investments	As of December 31, 2017 and 2016 , we held the following debt investments with an aggregate weighted average current yield of 9.31% , excluding our investment in Two Herald Square, at December 31, 2017 (in thousands): Loan Type December 31, 2017 Future Funding Obligations December 31, 2017 Senior Financing December 31, 2017 Carrying Value (1) December 31, 2016 Carrying Value (1) Maturity Date (2) Fixed Rate Investments: Mortgage/Jr. Mortgage Loan (3) $ — $ — $ 250,464 $ — April 2017 Mortgage Loan (4) — — 26,366 26,311 February 2019 Loan Type December 31, 2017 Future Funding Obligations December 31, 2017 Senior Financing December 31, 2017 Carrying Value (1) December 31, 2016 Carrying Value (1) Maturity Date (2) Mortgage Loan — — 239 380 August 2019 Mezzanine Loan (5a) — 1,160,000 204,005 — March 2020 Mezzanine Loan — 15,000 3,500 3,500 September 2021 Mezzanine Loan — 147,000 24,913 — April 2022 Mezzanine Loan — 86,976 12,699 12,692 November 2023 Mezzanine Loan (5b) — 115,000 12,932 12,925 June 2024 Mezzanine Loan — 95,000 30,000 30,000 January 2025 Mezzanine Loan — 340,000 15,000 15,000 November 2026 Mezzanine Loan — 1,657,500 55,250 — June 2027 Mezzanine Loan (6) — — — 66,129 Jr. Mortgage Participation/Mezzanine Loan (7) — — — 193,422 Total fixed rate $ — $ 3,616,476 $ 635,368 $ 360,359 Floating Rate Investments: Mezzanine Loan (5c)(8) $ 795 $ — $ 15,148 $ 15,051 March 2018 Mezzanine Loan — 40,000 19,982 19,913 April 2018 Jr. Mortgage Participation — 94,546 34,947 34,844 April 2018 Mezzanine Loan 523 20,523 10,934 10,863 August 2018 Mortgage/Mezzanine Loan — — 19,940 19,840 August 2018 Mortgage Loan — 65,000 14,955 14,880 August 2018 Mortgage/Mezzanine Loan (9) — — 16,969 16,960 September 2018 Mezzanine Loan — 37,500 14,855 14,648 September 2018 Mortgage/Mezzanine Loan (10) 391 — 23,609 20,423 October 2018 Mezzanine Loan 2,325 45,025 34,879 34,502 October 2018 Mezzanine Loan — 335,000 74,755 74,476 November 2018 Mezzanine Loan (5d)(11) — 85,000 15,381 15,141 December 2018 Mezzanine Loan (5e)(11) — 65,000 14,869 14,656 December 2018 Mezzanine Loan — 33,000 26,927 26,850 December 2018 Mezzanine Loan — 175,000 59,723 56,114 December 2018 Mezzanine Loan — 45,000 12,174 12,104 January 2019 Mortgage/Mezzanine Loan (5f) 26,284 — 162,553 — January 2019 Mezzanine Loan 5,372 25,289 8,550 5,410 January 2019 Mezzanine Loan — 38,000 21,939 21,891 March 2019 Mezzanine Loan 11 174,947 37,250 — April 2019 Mezzanine Loan — 265,000 24,830 24,707 April 2019 Mortgage/Jr. Mortgage Participation Loan 27,617 199,733 71,832 65,554 August 2019 Mezzanine Loan 2,034 189,829 37,851 37,322 September 2019 Mortgage/Mezzanine Loan 36,391 — 143,919 111,819 September 2019 Mezzanine Loan — 350,000 34,737 — October 2019 Mortgage/Mezzanine Loan 25,643 — 43,845 33,682 January 2020 Mezzanine Loan (12) 3,621 555,379 75,834 125,911 January 2020 Mezzanine Loan 6,913 34,337 11,259 — July 2020 Mezzanine Loan (13) 51,494 310,654 75,428 63,137 November 2020 Mortgage and Mezzanine Loan 42,510 — 88,989 — December 2020 Loan Type December 31, 2017 Future Funding Obligations December 31, 2017 Senior Financing December 31, 2017 Carrying Value (1) December 31, 2016 Carrying Value (1) Maturity Date (2) Mortgage and Mezzanine Loan — — 35,152 — December 2020 Jr. Mortgage Participation/Mezzanine Loan — 60,000 15,635 15,606 July 2021 Mezzanine Loan — 280,000 34,600 — August 2022 Mortgage/Mezzanine Loan (14) — — — 29,998 Mezzanine Loan (15) — — — 64,505 Mezzanine Loan (16) — — — 15,369 Mortgage/Mezzanine Loan (6) — — — 32,847 Mortgage/Mezzanine Loan (6) — — — 22,959 Mezzanine Loan (17) — — — 14,957 Mortgage/Mezzanine Loan (18) — — — 145,239 Total floating rate $ 231,924 $ 3,523,762 $ 1,334,250 $ 1,232,178 Total $ 231,924 $ 7,140,238 $ 1,969,618 $ 1,592,537 (1) Carrying value is net of discounts, premiums, original issue discounts and deferred origination fees. (2) Represents contractual maturity, excluding any unexercised extension options. (3) These loans were purchased at par in April and May 2017 and were in maturity default at the time of acquisition. At the time the loans were purchased, the Company expected to collect all contractually required payments, including interest. In August 2017, the Company determined that it was probable that the loans would not be repaid in full and therefore, the loans were put on non-accrual status. No impairment was recorded as the Company believes that the fair value of the property exceeds the carrying amount of the loans. The loans had an outstanding balance, including accrued interest, of $259.3 million at the time that they were put on non-accrual status. (4) In September 2014, we acquired a $26.4 million mortgage loan at a $0.2 million discount and a $5.7 million junior mortgage participation at a $5.7 million discount. The junior mortgage participation was a nonperforming loan at acquisition, is currently on non-accrual status and has no carrying value. (5) Carrying value is net of the following amounts that were sold or syndicated, which are included in other assets and other liabilities on the consolidated balance sheets as a result of the transfers not meeting the conditions for sale accounting: (a) $1.2 million , (b) $12.0 million , (c) $5.1 million (d) $14.6 million , (e) $14.1 million , and (f) $21.2 million . (6) This loan was repaid in June 2017. (7) This loan was repaid in March 2017. (8) This loan was extended in March 2018. (9) This loan was extended in August 2017. (10) This loan was extended in September 2017. (11) This loan was extended in December 2017. (12) $66.1 million of outstanding principal was syndicated in February 2017. (13) This loan was extended in November 2017. (14) This loan was repaid in December 2017. (15) This loan was repaid in November 2017. (16) This loan was repaid in September 2017. (17) This loan was contributed to a joint venture in May 2017. (18) This loan was repaid in January 2017.
Schedule of preferred equity investments	As of December 31, 2017 and 2016 , we held the following preferred equity investments with an aggregate weighted average current yield of 6.99% at December 31, 2017 (in thousands): Type December 31, 2017 Future Funding Obligations December 31, 2017 December 31, 2017 (1) December 31, 2016 (1) Mandatory Redemption (2) Preferred Equity $ — $ 272,000 $ 144,423 $ — April 2021 Preferred Equity (3) — — — 9,982 Preferred Equity (4) — — — 37,893 $ — $ 272,000 $ 144,423 $ 47,875 (1) Carrying value is net of deferred origination fees. (2) Represents contractual maturity, excluding any unexercised extension options. (3) This investment was redeemed in May 2017. (4) This investment was redeemed in April 2017. The following table is a rollforward of our total loan loss reserves at December 31, 2017 , 2016 and 2015 (in thousands): December 31, 2017 2016 2015 Balance at beginning of year $ — $ — $ — Expensed — — — Recoveries — — — Charge-offs and reclassifications — — — Balance at end of period $ — $ — $ —

Investments in Unconsolidated35

Investments in Unconsolidated Joint Ventures (Tables)	12 Months Ended
	Dec. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
Schedule of investment in real estate joint venture	The table below provides general information on each of our joint ventures as of December 31, 2017 : Property Partner Ownership Interest (1) Economic Interest (1) Unaudited Approximate Square Feet Acquisition Date (2) Acquisition Price (2) (in thousands) 131-137 Spring Street Invesco Real Estate 20.00% 20.00% 68,342 August 2015 $ 277,750 Mezzanine Loan (3) Private Investors 33.33% 33.33% — May 2017 15,000 (1) Ownership interest and economic interest represent the Company's interests in the joint venture as of December 31, 2017 . Changes in ownership or economic interests within the current year are disclosed in the notes below. (2) Acquisition date and price represent the date on which the Company initially acquired an interest in the joint venture and the actual or implied gross purchase price for the joint venture on that date. Acquisition date and price are not adjusted for subsequent acquisitions or dispositions of interest. (3) In May 2017, the Company contributed a mezzanine loan secured by a commercial property in midtown Manhattan to a joint venture and retained a 33.33% interest in the venture. The carrying value is net of $10.0 million that was sold, which is included in other assets and other liabilities on the consolidated balance sheets as a result of the transfers not meeting the conditions for sale accounting. The loan matures in November 2018. The following table summarizes the investments in unconsolidated joint ventures sold during the years ended December 31, 2017 , 2016 , and 2015 : Property Ownership Interest Disposition Date Type of Sale Gross Asset Valuation (in thousands) (1) Gain on Sale (in thousands) (2) 102 Greene Street 10.00% September 2017 Ownership Interest $ 43,500 $ 283 (1) Represents implied gross valuation for the joint venture or sales price of the property. (2) Represents the Company's share of the gain. As of December 31, 2017 and 2016 , the carrying value for acquisition, development and construction arrangements were as follows (in thousands): Loan Type December 31, 2017 December 31, 2016 Maturity Date Mezzanine Loan and Preferred Equity (1) $ 100,000 $ 100,000 March 2018 Mezzanine Loan (2) 26,716 24,542 July 2036 $ 126,716 $ 124,542 (1) The mezzanine loan was repaid and the preferred equity interest was redeemed in March 2018. (2) The Company has the ability to convert this loan into an equity position starting in 2021 and the borrower is able to force this conversion in 2024.
Schedule of first mortgage notes and other loans payable on joint venture properties	The first mortgage notes and other loans payable collateralized by the respective joint venture properties and assignment of leases at December 31, 2017 and 2016 , respectively, are as follows (amounts in thousands): Property Economic Interest (1) Maturity Date Interest Rate (2) December 31, 2017 December 31, 2016 Floating Rate Debt: 131-137 Spring Street 20.00 % August 2020 L+ 1.55% $ 141,000 $ 141,000 Total joint venture mortgages and other loans payable $ 141,000 $ 141,000 Deferred financing costs, net (2,862 ) (3,970 ) Total joint venture mortgages and other loans payable, net $ 138,138 $ 137,030 (1) Economic interest represents the Company's interests in the joint venture as of December 31, 2017 . Changes in ownership or economic interests, if any, within the current year are disclosed in the notes to the investment in unconsolidated joint ventures note above. (2) Interest rate as of December 31, 2017 . Floating rate debt is presented with the stated interest rate spread over 30-day LIBOR, unless otherwise specified.
Combined balance sheets for the unconsolidated joint ventures	The combined balance sheets for the unconsolidated joint ventures, at December 31, 2017 and 2016 are as follows (in thousands): December 31, 2017 December 31, 2016 Assets Commercial real estate property, net $ 273,116 $ 279,451 Debt and preferred equity investments, net 141,716 273,749 Other assets 15,735 18,922 Total assets $ 430,567 $ 572,122 Liabilities and members' equity Mortgages and other loans payable, net $ 138,138 $ 137,030 Other liabilities 18,908 22,185 Members' equity 273,521 412,907 Total liabilities and members' equity $ 430,567 $ 572,122 Company's investments in unconsolidated joint ventures $ 130,217 $ 174,127
Combined statements of operations for the unconsolidated joint ventures	The combined statements of operations for the unconsolidated joint ventures for the years ended December 31, 2017 , 2016 , and 2015 are as follows (in thousands): Year Ended December 31, 2017 2016 2015 Total revenues $ 35,204 $ 38,524 $ 19,855 Operating expenses 877 1,238 1,686 Real estate taxes 1,389 1,192 1,262 Interest expense, net of interest income 3,769 2,895 1,070 Amortization of deferred financing costs 1,114 1,108 462 Transaction related costs — — 5,262 Depreciation and amortization 8,405 8,404 3,207 Total expenses $ 15,554 $ 14,837 $ 12,949 Net income $ 19,650 $ 23,687 $ 6,906 Company's equity in net income from unconsolidated joint ventures 14,192 14,509 8,841

Mortgages and Other Loans Pay36

Mortgages and Other Loans Payable (Tables)	12 Months Ended
	Dec. 31, 2017
Mortgage Note and Other Loans Payable
Schedule of the first mortgage note and other loans payable collateralized by the property, assignment of leases and investment	The first mortgages and other loans payable collateralized by the respective properties and assignment of leases or debt investments at December 31, 2017 and 2016 , respectively, were as follows (amounts in thousands): Property Maturity Date Interest Rate (1) December 31, 2017 December 31, 2016 Fixed Rate Debt: 919 Third Avenue (2) June 2023 5.12% $ 500,000 $ 500,000 315 West 33rd Street February 2027 4.24% 250,000 — Floating Rate Debt: 2017 Master Repurchase Agreement June 2018 L+ 2.38% $ 90,809 $ — 2016 Master Repurchase Agreement (3) — 184,642 Total mortgages and other loans payable $ 840,809 $ 684,642 Deferred financing costs, net of amortization (11,161 ) (8,574 ) Total mortgages and other loans payable, net $ 829,648 $ 676,068 (1) Interest rate as of December 31, 2017 . Floating rate debt is presented with the stated interest rate spread over 30-day LIBOR, unless otherwise specified. (2) We own a 51.0% controlling interest in the consolidated joint venture that is the borrower on this loan. (3) The master repurchase agreement was repaid in October 2017.

Corporate Indebtedness (Tables)

Corporate Indebtedness (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Schedule of senior unsecured notes and other related disclosures by scheduled maturity date	The following table sets forth our senior unsecured notes and other related disclosures as of December 31, 2017 and 2016 , respectively, by scheduled maturity date (dollars in thousands): Issuance December 31, 2017 Unpaid Principal Balance December 31, 2017 Accreted Balance December 31, 2016 Accreted Balance Coupon (1) Initial Term Maturity Date August 5, 2011 (2) $ 250,000 $ 249,953 $ 249,880 5.00 % 7 August 2018 March 16, 2010 (2) 250,000 250,000 250,000 7.75 % 10 March 2020 November 15, 2012 (3) 300,000 305,163 200,000 4.50 % 10 December 2022 December 17, 2015 (2) 100,000 100,000 100,000 4.27 % 10 December 2025 $ 900,000 $ 905,116 $ 799,880 Deferred financing costs, net (4,049 ) (4,620 ) $ 900,000 $ 901,067 $ 795,260 (1) Interest on the senior unsecured notes is payable semi-annually with principal and unpaid interest due on the scheduled maturity dates. (2) Issued by SL Green, the Operating Partnership and ROP, as co-obligors. (3) In October 2017, SL Green, the Operating Partnership, and ROP, as co-obligors, issued an additional
Schedule of combined aggregate principal maturities of mortgage and other loans payable, 2012 credit facility and senior unsecured notes, including as-of-right extension options	Combined aggregate principal maturities of mortgages and other loans payable, and senior unsecured notes as of December 31, 2017 , including as-of-right extension options and put options, were as follows (in thousands): Scheduled Principal Senior Total 2018 $ — $ 90,809 $ 250,000 $ 340,809 2019 — — — — 2020 — — 250,000 250,000 2021 — — — — 2022 — — 300,000 300,000 Thereafter — 750,000 100,000 850,000 $ — $ 840,809 $ 900,000 $ 1,740,809
Schedule of consolidated interest expense, excluding capitalized interest	Consolidated interest expense, excluding capitalized interest, was comprised of the following (in thousands): Year Ended December 31, 2017 2016 2015 Interest expense before capitalized interest $ 124,507 $ 110,393 $ 120,467 Interest capitalized (533 ) (1,171 ) (1,107 ) Interest income (5 ) (14 ) (18 ) Interest expense, net $ 123,969 $ 109,208 $ 119,342

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value, by Balance Sheet Grouping	The following table provides the carrying value and fair value of these financial instruments as of December 31, 2017 and December 31, 2016 (in thousands): December 31, 2017 December 31, 2016 Carrying Value (1) Fair Value Carrying Value (1) Fair Value Debt and preferred equity investments $ 2,114,041 (2) $ 1,640,412 (2) Fixed rate debt $ 1,655,116 $ 1,715,501 $ 2,099,880 $ 2,183,042 Variable rate debt 90,809 92,087 567,642 580,083 $ 1,745,925 $ 1,807,588 $ 2,667,522 $ 2,763,125 (1) Amounts exclude net deferred financing costs. (2) At December 31, 2017 , debt and preferred equity investments had an estimated fair value ranging between $2.1 billion and $2.3 billion . At December 31, 2016 , debt and preferred equity investments had an estimated fair value ranging between $1.6 billion and $1.8 billion .

Financial Instruments_ Deriva39

Financial Instruments: Derivatives and Hedging (Tables)	12 Months Ended
	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of effect of derivative financial instruments on consolidated statements of income	The following table presents the effect of our derivative financial instruments that are designated and qualify as hedging instruments on the consolidated statements of operations for the years ended December 31, 2017 , 2016 , and 2015 , respectively (in thousands): Amount of Loss Recognized in Other Comprehensive Loss (Effective Portion) Location of Loss Reclassified from Accumulated Other Comprehensive Loss into Income Amount of Loss Reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion) Location of Gain Recognized in Income on Derivative Amount of Gain Recognized into Income (Ineffective Portion) Year Ended December 31, Year Ended December 31, Year Ended December 31, Derivative 2017 2016 2015 2017 2016 2015 2017 2016 2015 Interest Rate Swap $ — $ (13 ) $ (109 ) Interest expense $ 359 $ 611 $ 999 Interest expense $ — $ 3 $ 3

Rental Income (Tables)

Rental Income (Tables)	12 Months Ended
	Dec. 31, 2017
Leases [Abstract]
Schedule of approximate future minimum rents to be received over the next five years and thereafter	Approximate future minimum rents to be received over the next five years and thereafter for non-cancelable operating leases in effect at December 31, 2017 for the consolidated properties, including consolidated joint venture properties, are as follows (in thousands): 2018 $ 606,408 2019 578,008 2020 515,413 2021 466,618 2022 397,288 Thereafter 1,873,772 $ 4,437,507

Benefit Plans (Tables)

Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
Schedule of contributions made to multi-employer plans	Contributions we made to the multi-employer plans for the years ended December 31, 2017 , 2016 and 2015 are included in the table below (in thousands): Benefit Plan 2017 2016 2015 Pension Plan $ 2,269 $ 2,219 $ 1,533 Health Plan 6,764 6,366 4,843 Other plans 865 902 3,300 Total plan contributions $ 9,898 $ 9,487 $ 9,676

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Schedule of future minimum lease payments under capital leases and noncancellable operating leases	The following is a schedule of future minimum lease payments under non-cancellable operating leases with initial terms in excess of one year as of December 31, 2017 (in thousands): Non-cancellable operating leases 2018 $ 20,586 2019 20,586 2020 20,586 2021 20,736 2022 18,580 Thereafter 289,622 Total minimum lease payments $ 390,696

Quarterly Financial Data of t43

Quarterly Financial Data of the Company (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Summarized quarterly financial data	Summarized quarterly financial data for the years ended December 31, 2017 and 2016 , was as follows (in thousands): 2017 Quarter Ended December 31 September 30 June 30 March 31 Total revenues $ 241,463 $ 241,908 $ 251,812 $ 232,355 Income before equity in net income from unconsolidated joint ventures, equity in net gain on sale of interest in unconsolidated joint venture, gain (loss) on sale of real estate, depreciable real estate reserves and loss on early extinguishment of debt $ 76,973 $ 61,766 $ 83,947 $ 63,149 Equity in net income from unconsolidated joint ventures 3,830 2,927 3,180 4,255 Equity in net gain on sale of interest in unconsolidated joint venture 387 282 — 3 Gain on sale of real estate 64,779 114 4,933 — Depreciable real estate reserves (86,364 ) (379 ) (29,063 ) (56,265 ) Net income 59,605 64,710 62,997 11,142 Net (income) loss attributable to noncontrolling interests in other partnerships (2,147 ) 1,467 18,134 (14 ) Preferred units dividend (956 ) (955 ) (955 ) (953 ) Net income attributable to ROP common unitholder $ 56,502 $ 65,222 $ 80,176 $ 10,175 2016 Quarter Ended December 31 September 30 June 30 March 31 Total revenues $ 232,658 $ 271,336 $ 231,758 $ 239,664 Income from continuing operations before equity in net income from unconsolidated joint ventures, and loss on sale of real estate $ 66,056 $ 98,647 $ 71,254 $ 69,743 Equity in net income from unconsolidated joint ventures 4,110 4,276 3,666 2,457 Loss on sale of real estate, net (10 ) — (6,899 ) — Net income 70,156 102,923 68,021 72,200 Net income attributable to noncontrolling interests in other partnerships (1,071 ) (1,279 ) (2,062 ) (12 ) Preferred units dividend (956 ) (955 ) (955 ) (955 ) Net income attributable to ROP common unitholder $ 68,129 $ 100,689 $ 65,004 $ 71,233

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Schedule of selected results of operations and selected asset information	Selected results of operations for the years ended December 31, 2017 , 2016 and 2015 and selected asset information as of December 31, 2017 and 2016 , regarding our operating segments are as follows (in thousands): Real Estate Segment Debt and Preferred Equity Segment Total Company Total revenues: Years ended: December 31, 2017 $ 773,561 $ 193,977 $ 967,538 December 31, 2016 761,314 214,102 975,416 December 31, 2015 742,585 182,648 925,233 Income before equity in net gain on sale of interest in unconsolidated joint venture, gain (loss) on sale of real estate, depreciable real estate reserves and loss on early extinguishment of debt Years ended: December 31, 2017 $ 129,558 $ 170,469 $ 300,027 December 31, 2016 115,213 204,996 320,209 December 31, 2015 108,937 163,684 272,621 Total assets As of: December 31, 2017 $ 6,182,300 $ 2,359,208 $ 8,541,508 December 31, 2016 6,786,479 1,968,134 8,754,613
Schedule of reconciliation of income from continuing operations to net income attributable to SL Green common stockholders	The table below reconciles income from continuing operations to net income for the years ended December 31, 2017 , 2016 and 2015 (in thousands): Year ended December 31, 2017 2016 2015 Income before equity in net gain on sale of interest in unconsolidated joint venture/real estate, gain (loss) on sale of real estate, depreciable real estate reserves, and loss on early extinguishment of debt. $ 300,027 $ 320,209 $ 272,621 Equity in net gain on sale of interest in unconsolidated joint venture/real estate 672 — — Gain (loss) on sale of real estate, net 69,826 (6,909 ) 100,190 Depreciable real estate reserves (172,071 ) — (9,998 ) Loss on early extinguishment of debt — — (49 ) Net income $ 198,454 $ 313,300 $ 362,764

Organization and Basis of Pre45

Organization and Basis of Presentation (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)ft²property	Dec. 31, 2015USD ($)property	Aug. 31, 2015ft²
Real estate properties
Percentage of ownership in SL Green Operating Partnership owned by SL Green Realty Corp (as a percent)	95.42%
Number of properties transferred by parent company | property		2
Carrying value of properties transferred by SL Green | $		$ 395
Number of entities transferred by parent company | property		1
Carrying value of entities transferred by the parent company | $		$ 1,700
Number of Properties | property	36
Approximate Square Feet (unaudited)	11,429,846
Weighted Average Occupancy (unaudited)	93.90%
Mortgage loans on real estate, commercial and consumer, net including debt investments, other | $	$ 2,200
Debt investments, other | $	$ 100
131-137 Spring Street
Real estate properties
Approximate Square Feet (unaudited)			68,342
Suburban
Real estate properties
Number of Properties | property	14
Approximate Square Feet (unaudited)	2,202,400
Weighted Average Occupancy (unaudited)	85.90%
Office | Manhattan
Real estate properties
Number of Properties | property	16
Approximate Square Feet (unaudited)	8,463,245
Weighted Average Occupancy (unaudited)	95.90%
Office | Suburban
Real estate properties
Number of Properties | property	13
Approximate Square Feet (unaudited)	2,150,400
Weighted Average Occupancy (unaudited)	85.50%
Retail | 131-137 Spring Street
Real estate properties
Approximate Square Feet (unaudited)	68,342
Number of properties held for sale | property	2
Retail | Manhattan
Real estate properties
Number of Properties | property	5
Approximate Square Feet (unaudited)	364,816
Weighted Average Occupancy (unaudited)	98.00%
Retail | Suburban
Real estate properties
Number of Properties | property	1
Approximate Square Feet (unaudited)	52,000
Weighted Average Occupancy (unaudited)	100.00%
Fee Interest | Manhattan
Real estate properties
Number of Properties | property	1
Approximate Square Feet (unaudited)	176,530
Weighted Average Occupancy (unaudited)	100.00%
Commercial Properties
Real estate properties
Number of Properties | property	36
Approximate Square Feet (unaudited)	11,206,991
Weighted Average Occupancy (unaudited)	94.00%
Commercial Properties | Manhattan
Real estate properties
Number of Properties | property	22
Approximate Square Feet (unaudited)	9,004,591
Weighted Average Occupancy (unaudited)	96.00%
Residential | Manhattan
Real estate properties
Number of Properties | property	0
Approximate Square Feet (unaudited)	222,855
Weighted Average Occupancy (unaudited)	85.90%
Consolidated Properties | Dual property type, retail portion | Manhattan
Real estate properties
Approximate Square Feet (unaudited)	270,132
Consolidated Properties | Dual property type, residential portion | Manhattan
Real estate properties
Approximate Square Feet (unaudited)	222,855

Significant Accounting Polici46

Significant Accounting Policies - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Investment in Commercial Real Estate Properties
Weighted average amortization period, above-market leases (in years)	4 years 5 months 6 days
Weighted average amortization period, below-market leases (in years)	24 years 5 months 1 day
Weighted average amortization period, in-place leases (in years)	18 years 1 month 1 day
Maximum period of cessation of major construction activity to completion of construction project (in years)	1 year
Depreciation expense (including amortization of capital lease asset)	$ 188,900,000	$ 196,200,000	$ 187,200,000
Rental revenue from amortization of acquired leases	17,000,000	20,200,000	24,900,000
Increase (reduction) in interest expense from amortization of above-market rate mortgages	0	100,000	$ 400,000
Identified intangible assets (included in other assets):
Gross amount	276,163,000	311,830,000
Accumulated amortization	(236,737,000)	(253,064,000)
Net	39,426,000	58,766,000
Identified intangible liabilities (included in deferred revenue):
Gross amount	496,438,000	524,793,000
Accumulated amortization	(366,091,000)	(368,738,000)
Net	130,347,000	$ 156,055,000
Net intangible assets reclassified to assets held for sale	100,000
Net intangible liabilities reclassified to liabilities related to assets held for sale	$ 100,000
Above-market leases | Minimum
Investment in Commercial Real Estate Properties
Estimated useful life of intangible assets (years)	1 year
Above-market leases | Maximum
Investment in Commercial Real Estate Properties
Estimated useful life of intangible assets (years)	14 years
Below-market leases | Minimum
Investment in Commercial Real Estate Properties
Estimated useful life of intangible assets (years)	1 year
Below-market leases | Maximum
Investment in Commercial Real Estate Properties
Estimated useful life of intangible assets (years)	14 years
In-place leases | Minimum
Investment in Commercial Real Estate Properties
Estimated useful life of intangible assets (years)	1 year
In-place leases | Maximum
Investment in Commercial Real Estate Properties
Estimated useful life of intangible assets (years)	14 years
Building Fee Ownership
Investment in Commercial Real Estate Properties
Estimated useful life (years)	40 years
Building (leasehold interest) | Maximum
Investment in Commercial Real Estate Properties
Estimated useful life (years)	40 years
Furniture and fixtures | Minimum
Investment in Commercial Real Estate Properties
Estimated useful life (years)	4 years
Furniture and fixtures | Maximum
Investment in Commercial Real Estate Properties
Estimated useful life (years)	7 years
Building | Minimum
Investment in Commercial Real Estate Properties
Estimated useful life (years)	3 years
Building | Maximum
Investment in Commercial Real Estate Properties
Estimated useful life (years)	40 years

Significant Accounting Polici47

Significant Accounting Policies - Estimated Annual Amortization and Revenue Recognition (Details) $ in Thousands	Dec. 31, 2017USD ($)
Lease Agreements
Below Market Lease, Net, Amortization Income, Fiscal Year Maturity [Abstract]
2,018	$ (13,620)
2,019	(13,117)
2,020	(12,301)
2,021	(3,815)
2,022	(3,512)
Other Identifiable Assets
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2,018	8,188
2,019	6,641
2,020	5,830
2,021	2,985
2,022	$ 1,423

Significant Accounting Polici48

Significant Accounting Policies - Concentrations of Credit Risk and Reclassification (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Concentrations of Credit Risk
Financing receivable number of days past due for suspending income recognition	90 days
Loan loss reserves, net of recoveries	$ 0	$ 0	$ 0
Annualized cash rent | Customer concentration
Concentrations of Credit Risk
Maximum percentage of annualized cash rent for any one tenant not individually disclosed (more than)	5.00%
Annualized cash rent | Customer concentration | 919 Third Avenue
Concentrations of Credit Risk
Percentage of concentration	8.30%	8.10%	8.20%
Annualized cash rent | Customer concentration | 1185 Avenue of the Americas
Concentrations of Credit Risk
Percentage of concentration	15.60%	14.80%	15.40%
Annualized cash rent | Customer concentration | 625 Madison Avenue
Concentrations of Credit Risk
Percentage of concentration	10.20%	9.60%	9.70%
Annualized cash rent | Customer concentration | 750 Third Avenue
Concentrations of Credit Risk
Percentage of concentration	8.00%	7.70%	7.70%
Annualized cash rent | Customer concentration | 810 Seventh Avenue
Concentrations of Credit Risk
Percentage of concentration	8.00%	7.30%	7.50%
Annualized cash rent | Customer concentration | 555 W. 57th Street
Concentrations of Credit Risk
Percentage of concentration	6.90%	6.60%	6.70%
Annualized cash rent | Customer concentration | 1350 Avenue of the Americas
Concentrations of Credit Risk
Percentage of concentration	6.80%	6.40%	7.20%
Annualized cash rent | Customer concentration | 711 Third Avenue
Concentrations of Credit Risk
Percentage of concentration	5.10%	5.20%
Annualized cash rent | Customer concentration | 125 Park Avenue
Concentrations of Credit Risk
Percentage of concentration	6.80%	6.60%	6.60%

Property Acquisitions (Details)

Property Acquisitions (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jul. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed
Impact to rental revenue for amortization of aggregate below-market leases		$ 668,068	$ 652,629	$ 621,121
Impact to depreciation expense		$ 205,795	212,514	$ 202,474
110 Greene Street
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed
Land	$ 45,120
Building and building leasehold	215,470
Above-market lease value	0
Acquired in-place lease value	8,967
Other assets, net of other liabilities	0
Assets acquired	269,557
Mark-to-market assumed debt	0
Below-market lease value	(14,557)
Derivatives	0
Liabilities assumed	(14,557)
Purchase price	255,000
Net consideration funded by us at closing, excluding consideration financed by debt	255,000
Equity and/or debt investment held	0
Debt assumed	$ 0
Impact to rental revenue for amortization of aggregate below-market leases			1,600
Impact to depreciation expense			$ 3,100
Ownership interest in consolidated joint venture (as a percent)	90.00%
Scenario, Previously Reported | 110 Greene Street
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed
Land	$ 89,300
Building and building leasehold	165,800
Series P Preferred Units | 110 Greene Street
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed
Issuance of aggregate liquidation preference of preferred units	5,000
Series Q Preferred Units | 110 Greene Street
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed
Issuance of aggregate liquidation preference of preferred units	$ 6,700

Properties Held for Sale and 50

Properties Held for Sale and Property Dispositions (Details) $ in Thousands

1 Months Ended

3 Months Ended

12 Months Ended

Oct. 31, 2017USD ($)ft²

Sep. 30, 2017

Jul. 31, 2017USD ($)ft²

Apr. 30, 2017USD ($)ft²

May 31, 2016USD ($)a

Dec. 31, 2015USD ($)

Aug. 31, 2015USD ($)ft²

Dec. 31, 2017USD ($)ft²

Sep. 30, 2017USD ($)

Jun. 30, 2017USD ($)

Mar. 31, 2017USD ($)

Dec. 31, 2017USD ($)ft²

Dec. 31, 2016USD ($)

Dec. 31, 2015USD ($)

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Approximate Usable Square Feet (sqft) | ft²

11,429,846

11,429,846

Impairment charge

$ 86,364

$ 379

$ 29,063

$ 56,265

$ 172,071

$ 0

$ 9,998

115-117 Stevens Avenue

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Loss on disposal of property

17,800

1-6 International Drive

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Loss on disposal of property

69,100

125 Chubb Way

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Approximate Usable Square Feet (sqft) | ft²

278,000

Sales Price

$ 29,500

Gain (Loss) on Sale

$ (26,100)

Loss on disposal of property

26,100

16 Court Street

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Approximate Usable Square Feet (sqft) | ft²

317,600

Sales Price

$ 171,000

Gain (Loss) on Sale

$ 64,900

Employee compensation awards accrued

$ 2,500

680-750 Washington Boulevard

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Approximate Usable Square Feet (sqft) | ft²

325,000

Sales Price

$ 97,000

Gain (Loss) on Sale

$ (44,200)

Loss on disposal of property

44,200

520 White Plains Road

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Approximate Usable Square Feet (sqft) | ft²

180,000

Sales Price

$ 21,000

Gain (Loss) on Sale

$ (14,600)

Loss on disposal of property

$ 14,600

102 Greene Street

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Approximate Usable Square Feet (sqft) | ft²

9,200

Sales Price

$ 43,500

Gain (Loss) on Sale

$ 4,900

Disposal group, ownership interest

90.00%

Employee compensation awards accrued

$ 900

Joint venture ownership percentage sold

10.00%

90.00%

7 International Drive

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Approximate Usable Square Feet (sqft) | a

31

Sales Price

$ 20,000

Gain (Loss) on Sale

$ (6,900)

140 Grand Street

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Approximate Usable Square Feet (sqft) | ft²

130,100

130,100

Sales Price

$ 22,400

$ 22,400

Gain (Loss) on Sale

$ (10,500)

Impairment charge

$ 10,000

131-137 Spring Street

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Approximate Usable Square Feet (sqft) | ft²

68,342

Sales Price

$ 277,800

Gain (Loss) on Sale

101,100

Employee compensation awards accrued

$ 4,100

Ownership percentage in disposed asset

80.00%

Debt and Preferred Equity Inv51

Debt and Preferred Equity Investments - Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Mortgage Loans on Real Estate [Line Items]
Balance at beginning of period	$ 1,640,412	$ 1,670,020
Redemptions/sales/syndications/amortization	(813,418)	(1,044,482)
Balance at end of period	2,114,041	1,640,412
Debt Investments in Mortgage Loans
Mortgage Loans on Real Estate [Line Items]
Originations/Accretion	1,142,591	1,009,176
Preferred Equity Investments in Mortgage Loans
Mortgage Loans on Real Estate [Line Items]
Originations/Accretion	$ 144,456	$ 5,698

Debt and Preferred Equity Inv52

Debt and Preferred Equity Investments - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2014
Mortgage Loans on Real Estate [Line Items]
Aggregate weighted average current yield (as a percent)	9.31%
Mezzanine Loan with an Initial Maturity Date of March 2020
Debt Investments Held [Abstract]
Amount participated out	$ 1,200
Mezzanine Loan with an Initial Maturity Date of June 2024
Debt Investments Held [Abstract]
Amount participated out	12,000
Mezzanine Loan with an Initial Maturity Date of March 2018
Debt Investments Held [Abstract]
Amount participated out	5,100
Mezzanine Loan with an Initial Maturity Date of December 2018
Debt Investments Held [Abstract]
Amount participated out	14,600
Mezzanine Loan 2 with an Initial Maturity Date of December 2018
Debt Investments Held [Abstract]
Amount participated out	14,100
Mezzanine Loan with an Initial Maturity Date of January 2019
Debt Investments Held [Abstract]
Amount participated out	21,200
Debt Investments in Mortgage Loans
Debt Investments Held [Abstract]
Future Funding Obligations	231,924
Senior Financing	7,140,238
Carrying Value	1,969,618	$ 1,592,537
Total fixed rate
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	3,616,476
Carrying Value	635,368	360,359
Total fixed rate | Mortgage and Jr Mortgage Loan with an Initial Maturity Date of April 2017
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	250,464	0
Loan acquired	259,300
Total fixed rate | Mortgage Loan, February 2019
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	26,366	26,311
Loan acquired			$ 26,400
Discount amount			200
Total fixed rate | Mortgage Loan, August 2019
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	239	380
Total fixed rate | Mezzanine Loan with an Initial Maturity Date of March 2020
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	1,160,000
Carrying Value	204,005	0
Total fixed rate | Mezzanine Loan with an Initial Maturity Date of September 2021
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	15,000
Carrying Value	3,500	3,500
Total fixed rate | Mezzanine Loan with an Initial Maturity Date of April 2022
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	147,000
Carrying Value	24,913	0
Total fixed rate | Mezzanine Loan with an Initial Maturity Date of November 2023
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	86,976
Carrying Value	12,699	12,692
Total fixed rate | Mezzanine Loan with an Initial Maturity Date of June 2024
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	115,000
Carrying Value	12,932	12,925
Total fixed rate | Mezzanine Loan with an Initial Maturity Date of January 2025
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	95,000
Carrying Value	30,000	30,000
Total fixed rate | Mezzanine Loan with an Initial Maturity Date of November 2026
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	340,000
Carrying Value	15,000	15,000
Total fixed rate | Mezzanine Loan with an Initial Maturity Date of June 2027
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	1,657,500
Carrying Value	55,250	0
Total fixed rate | Mezzanine Loan Repaid in June 2017
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	0	66,129
Total fixed rate | Junior Mortgage Participation/Mezzanine Loan Repaid in March 2017
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	0	193,422
Total fixed rate | Junior Mortgage Participation Related to Mortgage Loan, February 2019
Debt Investments Held [Abstract]
Loan acquired			5,700
Discount amount			$ 5,700
Total floating rate
Debt Investments Held [Abstract]
Future Funding Obligations	231,924
Senior Financing	3,523,762
Carrying Value	1,334,250	1,232,178
Total floating rate | Mezzanine Loan with an Initial Maturity Date of March 2018
Debt Investments Held [Abstract]
Future Funding Obligations	795
Senior Financing	0
Carrying Value	15,148	15,051
Total floating rate | Junior Mortgage Participation, April 2018
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	94,546
Carrying Value	34,947	34,844
Total floating rate | Mezzanine Loan with an Initial Maturity Date of April 2018
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	40,000
Carrying Value	19,982	19,913
Total floating rate | Mortgage/Mezzanine Loan with an Initial Maturity Date of August 2018
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	19,940	19,840
Total floating rate | Mortgage/Mezzanine Loan 2 with an Initial Maturity Date of August 2018
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	65,000
Carrying Value	14,955	14,880
Total floating rate | Mortgage/Mezzanine Loan with an Initial Maturity Date of September 2018
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	16,969	16,960
Total floating rate | Mezzanine Loan with an Initial Maturity Date of August 2018
Debt Investments Held [Abstract]
Future Funding Obligations	523
Senior Financing	20,523
Carrying Value	10,934	10,863
Total floating rate | Mezzanine Loan with an Initial Maturity Date of September 2018
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	37,500
Carrying Value	14,855	14,648
Total floating rate | Mortgage/Mezzanine Loan with an Initial Maturity of October 2018
Debt Investments Held [Abstract]
Future Funding Obligations	391
Senior Financing	0
Carrying Value	23,609	20,423
Total floating rate | Mezzanine Loan with an Initial Maturity Date of October 2018
Debt Investments Held [Abstract]
Future Funding Obligations	2,325
Senior Financing	45,025
Carrying Value	34,879	34,502
Total floating rate | Mezzanine Loan with an Initial Maturity Date of November 2018
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	335,000
Carrying Value	74,755	74,476
Total floating rate | Mezzanine Loan with an Initial Maturity Date of December 2018
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	85,000
Carrying Value	15,381	15,141
Total floating rate | Mezzanine Loan 2 with an Initial Maturity Date of December 2018
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	65,000
Carrying Value	14,869	14,656
Total floating rate | Mezzanine Loan 3 with an Initial Maturity Date of December 2018
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	33,000
Carrying Value	26,927	26,850
Total floating rate | Mezzanine Loan 4 with an Initial Maturity Date of December 2018
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	175,000
Carrying Value	59,723	56,114
Total floating rate | Mezzanine Loan with an Initial Maturity Date of January 2019
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	45,000
Carrying Value	12,174	12,104
Total floating rate | Mortgage/Mezzanine Loan with an Initial Maturity Date of January 2019
Debt Investments Held [Abstract]
Future Funding Obligations	26,284
Senior Financing	0
Carrying Value	162,553	0
Total floating rate | Mezzanine Loan 3 with an Initial Maturity of January 2019
Debt Investments Held [Abstract]
Future Funding Obligations	5,372
Senior Financing	25,289
Carrying Value	8,550	5,410
Total floating rate | Mezzanine Loan, March 2019
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	38,000
Carrying Value	21,939	21,891
Total floating rate | Mezzanine Loan with an Initial Maturity Date of April 2019
Debt Investments Held [Abstract]
Future Funding Obligations	11
Senior Financing	174,947
Carrying Value	37,250	0
Total floating rate | Mezzanine Loan 2 with an Initial Maturity Date of April 2019
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	265,000
Carrying Value	24,830	24,707
Total floating rate | Mortgage/Jr Mortgage Participation Loan, Maturity Date of August 2019
Debt Investments Held [Abstract]
Future Funding Obligations	27,617
Senior Financing	199,733
Carrying Value	71,832	65,554
Total floating rate | Mezzanine Loan, Maturity of September 2019
Debt Investments Held [Abstract]
Future Funding Obligations	2,034
Senior Financing	189,829
Carrying Value	37,851	37,322
Total floating rate | Mortgage/Mezzanine Loan with an Initial Maturity Date of September 2019
Debt Investments Held [Abstract]
Future Funding Obligations	36,391
Senior Financing	0
Carrying Value	143,919	111,819
Total floating rate | Mezzanine Loan with an Initial Maturity Date of October 2019
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	350,000
Carrying Value	34,737	0
Total floating rate | Mortgage/Mezzanine Loan with an Initial Maturity Date of January 2020
Debt Investments Held [Abstract]
Future Funding Obligations	25,643
Senior Financing	0
Carrying Value	43,845	33,682
Total floating rate | Mezzanine Loan with an Initial Maturity Date of January 2020
Debt Investments Held [Abstract]
Future Funding Obligations	3,621
Senior Financing	555,379
Carrying Value	75,834	125,911
Amount participated out	66,100
Total floating rate | Mezzanine Loan with an Initial Maturity Date of July 2020
Debt Investments Held [Abstract]
Future Funding Obligations	6,913
Senior Financing	34,337
Carrying Value	11,259	0
Total floating rate | Mezzanine Loan with an Initial Maturity Date of November 2020
Debt Investments Held [Abstract]
Future Funding Obligations	51,494
Senior Financing	310,654
Carrying Value	75,428	63,137
Total floating rate | Mortgage/Mezzanine Loan with an Initial Maturity Date of December 2020
Debt Investments Held [Abstract]
Future Funding Obligations	42,510
Senior Financing	0
Carrying Value	88,989	0
Total floating rate | Mortgage/Mezzanine Loan 2 with an Initial Maturity Date of December 2020
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	35,152	0
Total floating rate | Jr Mortgage Participation/Mezzanine Loan with an Initial Maturity Date of July 2021
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	60,000
Carrying Value	15,635	15,606
Total floating rate | Mezzanine Loan With An Initial Maturity Date of August 2022
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	280,000
Carrying Value	34,600	0
Total floating rate | Mortgage/Mezzanine Loan Repaid in December 2017
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	0	29,998
Total floating rate | Mezzanine Loan Repaid in November 2017
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	0	64,505
Total floating rate | Mezzanine Loan Repaid in September 2017
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	0	15,369
Total floating rate | Mortgage/Mezzanine Loan Repaid in June 2017
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	0	32,847
Total floating rate | Mortgage/Mezzanine Loan 2 Repaid in June 2017
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	0	22,959
Total floating rate | Mezzanine Loan Contributed to Joint Venture in May 2017
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	0	14,957
Total floating rate | Mortgage/Mezzanine Loan Repaid in January 2017
Debt Investments Held [Abstract]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	$ 0	$ 145,239

Debt and Preferred Equity Inv53

Debt and Preferred Equity Investments - Preferred Equity Investments (Details)	12 Months Ended
	Dec. 31, 2017USD ($)segment	Dec. 31, 2016USD ($)segment	Dec. 31, 2015USD ($)
Mortgage Loans on Real Estate [Line Items]
Interest rate (as a percent)	9.31%
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of year	$ 0	$ 0	$ 0
Expensed	0	0	0
Recoveries	0	0	0
Charge-offs and reclassifications	0	0	0
Balance at end of period	$ 0	$ 0	$ 0
Number of portfolio segments of financial receivables (segment) | segment	1	1
Additional amount of financing receivables included in other assets	$ 93,400,000	$ 144,500,000
Preferred Equity, April 2021
Mortgage Loans on Real Estate [Line Items]
Future Funding Obligations	0
Senior Financing	272,000,000
Carrying Value	144,423,000	0
Preferred Equity Redeemed in May 2017
Mortgage Loans on Real Estate [Line Items]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	0	9,982,000
Preferred Equity Redeemed in April 2017
Mortgage Loans on Real Estate [Line Items]
Future Funding Obligations	0
Senior Financing	0
Carrying Value	$ 0	37,893,000
Preferred Equity Investments
Mortgage Loans on Real Estate [Line Items]
Interest rate (as a percent)	6.99%
Future Funding Obligations	$ 0
Senior Financing	272,000,000
Carrying Value	144,423,000	$ 47,875,000
Junior Mortgage Participation Acquired in September 2014
Mortgage Loans on Real Estate [Line Items]
Carrying Value	$ 0

Investments in Unconsolidated54

Investments in Unconsolidated Joint Ventures - Additional Information (Details) $ in Thousands	1 Months Ended	3 Months Ended								12 Months Ended
	May 31, 2017USD ($)	Dec. 31, 2017USD ($)ft²	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Sep. 30, 2016USD ($)	Jun. 30, 2016USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2017USD ($)ft²note	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Schedule of Equity Method Investments [Line Items]
Approximate Square Feet (unaudited) | ft²		11,429,846								11,429,846
Loans receivable, gross, commercial, acquisition		$ 126,716				$ 124,542				$ 126,716	$ 124,542
Total mortgages and other loans payable		840,809				684,642				840,809	684,642
Total joint venture mortgages and other loans payable		829,648				676,068				829,648	676,068
Commercial real estate property, net		5,536,852				6,071,648				5,536,852	6,071,648
Debt and preferred equity investments		2,114,041				1,640,412				2,114,041	1,640,412
Other assets		245,598				374,091				245,598	374,091
Other liabilities		92,514				160,982				92,514	160,982
Company's investments in unconsolidated joint ventures		130,217				174,127				130,217	174,127
Operating expenses										164,219	166,137	$ 163,969
Real estate taxes										156,967	152,010	143,873
Amortization of deferred financing costs										9,313	7,918	7,519
Depreciation and amortization										205,795	212,514	202,474
Total expenses										681,703	669,716	661,453
Equity in net income from unconsolidated joint ventures		$ 3,830	$ 2,927	$ 3,180	$ 4,255	4,110	$ 4,276	$ 3,666	$ 2,457	$ 14,192	14,509	8,841
131-137 Spring Street
Schedule of Equity Method Investments [Line Items]
Ownership Interest		20.00%								20.00%
Economic Interest (as a percent)		20.00%								20.00%
Approximate Square Feet (unaudited) | ft²		68,342								68,342
Acquisition Price		$ 277,750								$ 277,750
76 11th Avenue
Schedule of Equity Method Investments [Line Items]
Ownership Interest		33.33%								33.33%
Economic Interest (as a percent)		33.33%								33.33%
Approximate Square Feet (unaudited) | ft²		0								0
Acquisition Price		$ 15,000								$ 15,000
Corporate Joint Venture
Schedule of Equity Method Investments [Line Items]
Total joint venture mortgages and other loans payable		141,000				141,000				141,000	141,000
Deferred financing costs, net		(2,862)				(3,970)				(2,862)	(3,970)
Total joint venture mortgages and other loans payable, net		138,138				137,030				138,138	137,030
Commercial real estate property, net		273,116				279,451				273,116	279,451
Debt and preferred equity investments		141,716				273,749				141,716	273,749
Other assets		15,735				18,922				15,735	18,922
Total assets		430,567				572,122				430,567	572,122
Mortgages and other loans payable, net		138,138				137,030				138,138	137,030
Other liabilities		18,908				22,185				18,908	22,185
Members' equity		273,521				412,907				273,521	412,907
Total liabilities and members' equity		430,567				572,122				430,567	572,122
Company's investments in unconsolidated joint ventures		130,217				174,127				130,217	174,127
Total revenues										35,204	38,524	19,855
Operating expenses										877	1,238	1,686
Real estate taxes										1,389	1,192	1,262
Interest expense, net of interest income										3,769	2,895	1,070
Amortization of deferred financing costs										1,114	1,108	462
Transaction related costs										0	0	5,262
Depreciation and amortization										8,405	8,404	3,207
Total expenses										15,554	14,837	12,949
Net income										19,650	23,687	6,906
Equity in net income from unconsolidated joint ventures										14,192	14,509	$ 8,841
Corporate Joint Venture | 131-137 Spring Street
Schedule of Equity Method Investments [Line Items]
Total mortgages and other loans payable		141,000				141,000				$ 141,000	141,000
Corporate Joint Venture | 76 11th Avenue
Schedule of Equity Method Investments [Line Items]
Number of mezzanine notes secured | note										2
Mezzanine Loan
Schedule of Equity Method Investments [Line Items]
Ownership Interest	33.33%
Equity method investment, amount sold	$ 10,000
Participating Financing Due March 2017
Schedule of Equity Method Investments [Line Items]
Loans receivable, gross, commercial, acquisition		100,000				100,000				$ 100,000	100,000
Mezzanine Loan Due July 2036
Schedule of Equity Method Investments [Line Items]
Loans receivable, gross, commercial, acquisition		$ 26,716				$ 24,542				$ 26,716	$ 24,542
Weighted Average | Corporate Joint Venture | 131-137 Spring Street
Schedule of Equity Method Investments [Line Items]
Interest Rate (as a percent)		1.55%								1.55%

Investments in Unconsolidated55

Investments in Unconsolidated Joint Ventures - Sale of Joint Venture Interests or Properties (Details) - 102 Greene Street $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Schedule of Equity Method Investments [Line Items]
Ownership Interest	10.00%
Gross Asset Valuation	$ 43,500
Gain on Sale	$ 283

Mortgages and Other Loans Pay56

Mortgages and Other Loans Payable (Details)	12 Months Ended
	Dec. 31, 2017USD ($)extension_optiondebt_instrument	Dec. 31, 2016USD ($)
Mortgage note and other loan payable
Total mortgages and other loans payable	$ 840,809,000	$ 684,642,000
Deferred financing costs, net of amortization	(11,161,000)	(8,574,000)
Total mortgages and other loans payable, net	829,648,000	676,068,000
Collateral already posted, aggregate fair value	$ 1,900,000,000	1,700,000,000
Number of extension options | extension_option	2
Period of extension option	1 year
Uncommitted Master Repurchase Agreements
Mortgage note and other loan payable
Number of debt instruments | debt_instrument	2
Uncommitted Master Repurchase Agreement, 2
Mortgage note and other loan payable
Maximum borrowing capacity	$ 300,000,000
Debt instrument, term	1 year
Revolving credit facility, net	$ 90,100,000
2017 Master Repurchase Agreement
Mortgage note and other loan payable
Total mortgages and other loans payable	90,809,000	0
2016 Master Repurchase Agreement
Mortgage note and other loan payable
Total mortgages and other loans payable	0	184,642,000
Maximum borrowing capacity	$ 300,000,000
Debt instrument, term	2 years
Period of extension option	1 year
Revolving credit facility, net	$ (1,200,000)
Basis point fee (as a percent)	0.25%
Threshold amount for basis point fee to be applicable (less than)	$ 150,000,000
919 Third Avenue
Mortgage note and other loan payable
Total fixed rate debt	$ 500,000,000	500,000,000
Controlling interest in the joint venture (as a percent)	51.00%
315 West 33rd Street
Mortgage note and other loan payable
Total fixed rate debt	$ 250,000,000	$ 0
Weighted Average | 2017 Master Repurchase Agreement
Mortgage note and other loan payable
Interest Rate (as a percent)	2.38%
Weighted Average | 2016 Master Repurchase Agreement
Mortgage note and other loan payable
Interest Rate (as a percent)
Weighted Average | 919 Third Avenue
Mortgage note and other loan payable
Interest rate (as a percent)	5.12%
Weighted Average | 315 West 33rd Street
Mortgage note and other loan payable
Interest rate (as a percent)	4.24%
LIBOR | Minimum | 2016 Master Repurchase Agreement
Mortgage note and other loan payable
Interest rate (as a percent)	2.25%
LIBOR | Maximum | 2016 Master Repurchase Agreement
Mortgage note and other loan payable
Interest rate (as a percent)	4.00%

Corporate Indebtedness (Details

Corporate Indebtedness (Details)	1 Months Ended	12 Months Ended
	Oct. 31, 2017USD ($)	Dec. 31, 2017USD ($)extension_option	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Nov. 30, 2017USD ($)
Corporate Indebtedness
Number of extension options | extension_option		2
Period of extension option		1 year
Scheduled amortization and principal repayments
2,018		$ 340,809,000
2,019		0
2,020		250,000,000
2,021		0
2,022		300,000,000
Thereafter		850,000,000
Total amortization of debt and principal repayments		1,740,809,000
Interest expense
Interest expense before capitalized interest		124,507,000	$ 110,393,000	$ 120,467,000
Interest capitalized		(533,000)	(1,171,000)	(1,107,000)
Interest income		(5,000)	(14,000)	(18,000)
Interest expense, net		123,969,000	109,208,000	$ 119,342,000
Revolving credit facility
Corporate Indebtedness
Maximum borrowing capacity		$ 1,500,000,000
Number of extension options | extension_option		2
Period of extension option		6 months
Maximum borrowing capacity, optional expansion		$ 4,500,000,000
Revolving credit facility, net		40,000,000
Term loan
Corporate Indebtedness
Maximum borrowing capacity		1,500,000,000
Term Loan A
Corporate Indebtedness
Maximum borrowing capacity		1,300,000,000
Term Loan B
Corporate Indebtedness
Maximum borrowing capacity		200,000,000
2017 Credit Facility
Corporate Indebtedness
Ability to borrow under line of credit facility		1,400,000,000
Credit Facility 2012
Corporate Indebtedness
Letters of credit		11,800,000
Mortgage and Other Loans Payable
Scheduled Amortization
2,018		0
2,019		0
2,020		0
2,021		0
2,022		0
Thereafter		0
Total amortization of debt		0
Principal
2,018		90,809,000
2,019		0
2,020		0
2,021		0
2,022		0
Thereafter		750,000,000
Total principal repayments		840,809,000
Senior Unsecured Notes
Scheduled amortization and principal repayments
2,018		250,000,000
2,019		0
2,020		250,000,000
2,021		0
2,022		300,000,000
Thereafter		100,000,000
Total amortization of debt and principal repayments		900,000,000
Line of Credit | Revolving credit facility
Scheduled amortization and principal repayments
Total amortization of debt and principal repayments		30,300,000	(6,300,000)
Line of Credit | Term loan
Scheduled amortization and principal repayments
Total amortization of debt and principal repayments		1,500,000,000	1,200,000,000
Line of Credit | Credit Facility 2012
Scheduled amortization and principal repayments
Total amortization of debt and principal repayments					$ 1,200,000,000
Senior Unsecured Bonds | 4.50% senior unsecured notes maturing in December 2022
Debt disclosures by scheduled maturity date
Interest rate	4.50%
Face amount	$ 100,000,000
Redemption price, percentage	105.334%
Senior Unsecured Notes
Debt disclosures by scheduled maturity date
Unpaid principal balance		900,000,000
Accreted Balance		905,116,000	799,880,000
Deferred financing costs, net		(4,049,000)	(4,620,000)
Senior notes, net of deferred finance costs		901,067,000	795,260,000
Senior Unsecured Notes | 5.00% senior unsecured notes maturing on August 15, 2018
Debt disclosures by scheduled maturity date
Unpaid principal balance		250,000,000
Accreted Balance		$ 249,953,000	249,880,000
Interest rate		5.00%
Debt instrument, term		7 years
Senior Unsecured Notes | 7.75% senior unsecured notes maturing on March 15, 2020
Debt disclosures by scheduled maturity date
Unpaid principal balance		$ 250,000,000
Accreted Balance		$ 250,000,000	250,000,000
Interest rate		7.75%
Debt instrument, term		10 years
Senior Unsecured Notes | 4.50% senior unsecured notes maturing on December 01, 2022
Debt disclosures by scheduled maturity date
Unpaid principal balance		$ 300,000,000
Accreted Balance		$ 305,163,000	200,000,000
Interest rate		4.50%
Debt instrument, term		10 years
Senior Unsecured Notes | 4.27% senior unsecured notes maturing on December 17, 2025
Debt disclosures by scheduled maturity date
Unpaid principal balance		$ 100,000,000
Accreted Balance		$ 100,000,000	$ 100,000,000
Interest rate		4.27%
Debt instrument, term		10 years
Senior Unsecured Notes | 3.25% senior unsecured notes maturing in October 2022
Debt disclosures by scheduled maturity date
Accreted Balance		$ 499,500,000
Interest rate		3.25%

Preferred Units (Details)

Preferred Units (Details)	12 Months Ended
	Dec. 31, 2017USD ($)$ / sharesshares	Aug. 31, 2015shares	Jul. 22, 2015USD ($)
Class of Stock [Line Items]
Number of company common stock issued on conversion of Series B preferred units	6.71348
Series A Preferred Units
Class of Stock [Line Items]
Fair value of embedded derivative liability | $	$ 0		$ 0
Partnership Interest | Series A Preferred Units
Class of Stock [Line Items]
Shares of common stock reserved for issuance upon redemption of units of limited partnership interest in operating partnership (shares)	109,161
Dividend rate preferred units (as a percent)	3.50%
Liquidation preference of preferred units (in dollars per share) | $ / shares	$ 1,000
Number of preferred units issued (in shares)		109,161
Annual dividends on preferred units (in dollars per share) | $ / shares	$ 35
Partnership Interest | Series B Preferred Units
Class of Stock [Line Items]
Number of preferred units issued (in shares)	0

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value of Financial Instruments
Interest rate cap and swap agreements (included in other assets)	$ 167	$ 0
Debt and preferred equity investments	2,114,041	1,640,412
Level 1
Fair Value of Financial Instruments
Interest rate cap and swap agreements (included in other assets)	0	0
Level 2
Fair Value of Financial Instruments
Interest rate cap and swap agreements (included in other assets)	167	0
Level 3
Fair Value of Financial Instruments
Interest rate cap and swap agreements (included in other assets)	0	0
Carrying Value
Fair Value of Financial Instruments
Debt and preferred equity investments	2,114,041	1,640,412
Fixed rate debt	1,655,116	2,099,880
Variable rate debt	90,809	567,642
Total	1,745,925	2,667,522
Fair Value | Level 3
Fair Value of Financial Instruments
Fixed rate debt	1,715,501	2,183,042
Variable rate debt	92,087	580,083
Total	1,807,588	2,763,125
Minimum | Fair Value
Fair Value of Financial Instruments
Mortgage loans on real estate, fair value, low end of range	2,100,000	1,600,000
Maximum | Fair Value
Fair Value of Financial Instruments
Mortgage loans on real estate, fair value, high end of range	2,300,000	$ 1,800,000
Fixed rate | Mortgage and Jr Mortgage Loan with an Initial Maturity Date of April 2017
Fair Value of Financial Instruments
Notes receivable	250,000
Loans outstanding balance in non accrual status	$ 259,300

Financial Instruments_ Deriva60

Financial Instruments: Derivatives and Hedging (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative [Line Items]
Fair Value	$ 167,000	$ 0
Gain (loss) from changes in fair value	200,000
Fair value of derivatives in a net liability position	0
Aggregate termination value	0
Loss from settlement of hedges included in accumulated other comprehensive loss	1,300,000	1,600,000
Estimated current balance held in accumulated other comprehensive loss to be reclassified into earnings within the next 12 months	400,000
Amount of Loss Recognized in Other Comprehensive Loss (Effective Portion)	0	(13,000)	$ (109,000)
Amount of Loss Reclassified from Accumulated Other Comprehensive Loss into Income (Effective Portion)	359,000	611,000	999,000
Amount of Gain Recognized into Income (Ineffective Portion)	0	$ 3,000	$ 3,000
Interest Rate Swap
Derivative [Line Items]
Fair Value	167,000
Interest Rate Swap Expiring January 2019
Derivative [Line Items]
Notional Value	$ 21,394,000
Strike Rate	12.00%
Fair Value	$ 167,000

Rental Income (Details)

Rental Income (Details) - Consolidated Properties $ in Thousands	Dec. 31, 2017USD ($)
Approximate future minimum rents to be received over the next five years and thereafter for non-cancelable operating leases
2,018	$ 606,408
2,019	578,008
2,020	515,413
2,021	466,618
2,022	397,288
Thereafter	1,873,772
Total minimum lease payments	$ 4,437,507

Related Party Transactions (Det

Related Party Transactions (Details) - Affiliate - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Aug. 22, 2016
Related Party Transactions
Profit participation received from related party	$ 3.4	$ 3.3	$ 3.3
Alliance Building Services
Related Party Transactions
Payments made for services	10	8.1	9.9
SL Green
Related Party Transactions
Allocation of salary and other operating costs from related party	12.8	11.5	10.4
Insurance expense incurred	$ 5.4	$ 5.9	$ 6.6
Related party payable				$ 23.8
Interest rate				6.00%

Benefit Plans - Additional Info

Benefit Plans - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Jun. 30, 2014
Multi-employer plans
Plan contributions from all employers	$ 9,898	$ 9,487		$ 9,676
Health Plan
Multi-employer plans
Plan contributions from all employers			$ 1,300,000		$ 1,200,000	$ 1,100,000
Contributions by company (less than)	5.00%
Pension Plan
Multi-employer plans
Surcharge	No
Plan contributions from all employers			$ 257,800		$ 249,500	$ 221,900

Benefit Plans - Contributions M

Benefit Plans - Contributions Made to Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Multi-employer plans
Plan contributions	$ 9,898	$ 9,487	$ 9,676
Health Plan
Multi-employer plans
Plan contributions	6,764	6,366	4,843
Other plans
Multi-employer plans
Plan contributions	865	902	3,300
Pension Plan
Multi-employer plans
Plan contributions	$ 2,269	$ 2,219	$ 1,533

Commitments and Contingencies65

Commitments and Contingencies (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)extension_option
Other Commitments [Line Items]
Minimum initial term of noncancellable operating leases (in years)	1 year
Non-cancellable operating leases
2,018	$ 20,586
2,019	20,586
2,020	20,586
2,021	20,736
2,022	18,580
Thereafter	289,622
Total minimum lease payments	$ 390,696
711 Third Avenue
Other Commitments [Line Items]
Percentage of the fee not owned by the entity	50.00%
711 Third Avenue | Through July 2016
Other Commitments [Line Items]
Number of renewal options available | extension_option	5
Term of first renewal option (in years)	10 years
Required annual ground lease payments	$ 5,250
711 Third Avenue | After July 2016
Other Commitments [Line Items]
Required annual ground lease payments	$ 5,500
461 Fifth Avenue
Other Commitments [Line Items]
Number of renewal options available | extension_option	2
Required annual ground lease payments	$ 2,100
Term of second renewal option (in years)	21 years
Term of third renewal option (in years)	15 years
625 Madison Avenue
Other Commitments [Line Items]
Number of renewal options available | extension_option	2
Required annual ground lease payments	$ 4,600
Term of second renewal option (in years)	23 years
1185 Avenue of the Americas
Other Commitments [Line Items]
Term of first renewal option (in years)	23 years
Required annual ground lease payments	$ 6,900
919 Third Avenue
Other Commitments [Line Items]
Required annual ground lease payments	900
1055 Washington Boulevard
Other Commitments [Line Items]
Required annual ground lease payments	$ 600

Quarterly Financial Data of t66

Quarterly Financial Data of the Company (unaudited) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 241,463	$ 241,908	$ 251,812	$ 232,355	$ 232,658	$ 271,336	$ 231,758	$ 239,664	$ 967,538	$ 975,416	$ 925,233
Income from continuing operations before equity in net income from unconsolidated joint ventures, and loss on sale of real estate	76,973	61,766	83,947	63,149	66,056	98,647	71,254	69,743	285,835	305,700	263,780
Equity in net income from unconsolidated joint ventures	3,830	2,927	3,180	4,255	4,110	4,276	3,666	2,457	14,192	14,509	8,841
Equity in net gain on sale of interest in unconsolidated joint venture	387	282	0	3					672	0	0
Gain on sale of real estate	64,779	114	4,933	0	(10)	0	(6,899)	0	69,826	(6,909)	100,190
Depreciable real estate reserves	(86,364)	(379)	(29,063)	(56,265)					(172,071)	0	(9,998)
Net income	59,605	64,710	62,997	11,142	70,156	102,923	68,021	72,200	198,454	313,300	362,764
Net loss (income) attributable to noncontrolling interests in other partnerships	(2,147)	1,467	18,134	(14)	(1,071)	(1,279)	(2,062)	(12)	17,440	(4,424)	(9,169)
Preferred units dividend	(956)	(955)	(955)	(953)	(956)	(955)	(955)	(955)	(3,819)	(3,821)	(1,698)
Net income attributable to ROP common unitholder	$ 56,502	$ 65,222	$ 80,176	$ 10,175	$ 68,129	$ 100,689	$ 65,004	$ 71,233	$ 212,075	$ 305,055	$ 351,897

Segment Information (Details)

Segment Information (Details) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Sep. 30, 2016USD ($)	Jun. 30, 2016USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2017USD ($)segment	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Segment information
Number of reportable segments | segment										2
Total revenues		$ 241,463	$ 241,908	$ 251,812	$ 232,355	$ 232,658	$ 271,336	$ 231,758	$ 239,664	$ 967,538	$ 975,416	$ 925,233
Income before equity in net gain on sale of interest in unconsolidated joint venture/real estate, gain (loss) on sale of real estate, depreciable real estate reserves, and loss on early extinguishment of debt.										300,027	320,209	272,621
Total assets	[1]	8,541,508				8,754,613				8,541,508	8,754,613
Equity in net gain on sale of interest in unconsolidated joint venture		387	282	0	3					672	0	0
Gain (loss) on sale of real estate		64,779	114	4,933	0	(10)	0	(6,899)	0	69,826	(6,909)	100,190
Depreciable real estate reserves		(86,364)	(379)	(29,063)	(56,265)					(172,071)	0	(9,998)
Loss on early extinguishment of debt										0	0	(49)
Net income		59,605	$ 64,710	$ 62,997	$ 11,142	70,156	$ 102,923	$ 68,021	$ 72,200	198,454	313,300	362,764
Operating Segments | Real Estate Segment
Segment information
Total revenues										773,561	761,314	742,585
Income before equity in net gain on sale of interest in unconsolidated joint venture/real estate, gain (loss) on sale of real estate, depreciable real estate reserves, and loss on early extinguishment of debt.										129,558	115,213	108,937
Total assets		6,182,300				6,786,479				6,182,300	6,786,479
Operating Segments | Debt and Preferred Equity Segment
Segment information
Total revenues										193,977	214,102	182,648
Income before equity in net gain on sale of interest in unconsolidated joint venture/real estate, gain (loss) on sale of real estate, depreciable real estate reserves, and loss on early extinguishment of debt.										170,469	204,996	$ 163,684
Total assets		$ 2,359,208				$ 1,968,134				$ 2,359,208	$ 1,968,134
[1]	The Company's consolidated balance sheets include assets and liabilities of consolidated variable interest entities ("VIEs"). See Note 2. The consolidated balance sheets include the following amounts related to our consolidated VIEs: $268.6 million and $297.3 million of land, $1.3 billion and $1.4 billion of building and improvements, $319.1 million and $318.4 million of accumulated depreciation, $143.9 million and $160.5 million of other assets included in other line items, $495.0 million and $494.0 million of real estate debt, net, $2.1 million and $2.1 million of accrued interest payable, and $48.8 million and $61.4 million of other liabilities included in other line items as of December 31, 2017 and December 31, 2016, respectively.

Schedule II_Valuation and Qua68

Schedule II—Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Tenant and other receivables—allowance
Changes in valuation allowance
Balance at Beginning of Year	$ 4,879	$ 5,593	$ 5,820
Additions Charged Against Operations/Recovery	3,657	3,604	4,363
Uncollectible Accounts Written-off	(1,299)	(4,318)	(4,590)
Balance at End of Year	7,237	4,879	5,593
Deferred rent receivable—allowance
Changes in valuation allowance
Balance at Beginning of Year	17,798	14,788	17,745
Additions Charged Against Operations/Recovery	2,084	3,955	1,775
Uncollectible Accounts Written-off	(8,693)	(945)	(4,732)
Balance at End of Year	$ 11,189	$ 17,798	$ 14,788

Schedule III_Real Estate And 69

Schedule III—Real Estate And Accumulated Depreciation - Real Estate And Accumulated Depreciation (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Real Estate And Accumulated Depreciation
Encumbrances	$ 750,000
Initial Cost
Land	1,700,062
Building & Improvements	4,604,432
Cost Capitalized Subsequent To Acquisition
Land	4,080
Building & Improvements	720,881
Gross Amount at Which Carried at Close of Period
Land	1,704,142
Building & Improvements	5,325,313
Total	7,029,455	$ 7,508,870	$ 7,428,243	$ 7,203,216
Accumulated Depreciation	1,492,603	$ 1,437,222	$ 1,267,598	$ 1,123,412
810 Seventh Avenue
Real Estate And Accumulated Depreciation
Encumbrances	0
Initial Cost
Land	114,077
Building & Improvements	476,386
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	71,735
Gross Amount at Which Carried at Close of Period
Land	114,077
Building & Improvements	548,121
Total	662,198
Accumulated Depreciation	162,606
461 Fifth Avenue
Real Estate And Accumulated Depreciation
Encumbrances	0
Initial Cost
Land	0
Building & Improvements	62,695
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	16,185
Gross Amount at Which Carried at Close of Period
Land	0
Building & Improvements	78,880
Total	78,880
Accumulated Depreciation	28,378
750 Third Avenue
Real Estate And Accumulated Depreciation
Encumbrances	0
Initial Cost
Land	51,093
Building & Improvements	205,972
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	42,543
Gross Amount at Which Carried at Close of Period
Land	51,093
Building & Improvements	248,515
Total	299,608
Accumulated Depreciation	93,469
919 Third Avenue
Real Estate And Accumulated Depreciation
Encumbrances	500,000
Initial Cost
Land	223,529
Building & Improvements	1,033,198
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	65,089
Gross Amount at Which Carried at Close of Period
Land	223,529
Building & Improvements	1,098,287
Total	1,321,816
Accumulated Depreciation	$ 303,424
Interest in property (as a percent)	51.00%
555 W. 57th Street
Real Estate And Accumulated Depreciation
Encumbrances	$ 0
Initial Cost
Land	18,846
Building & Improvements	78,704
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	61,424
Gross Amount at Which Carried at Close of Period
Land	18,846
Building & Improvements	140,128
Total	158,974
Accumulated Depreciation	64,281
1185 Avenue of the Americas
Real Estate And Accumulated Depreciation
Encumbrances	0
Initial Cost
Land	0
Building & Improvements	728,213
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	47,793
Gross Amount at Which Carried at Close of Period
Land	0
Building & Improvements	776,006
Total	776,006
Accumulated Depreciation	242,681
1350 Avenue of the Americas
Real Estate And Accumulated Depreciation
Encumbrances	0
Initial Cost
Land	91,038
Building & Improvements	380,744
Cost Capitalized Subsequent To Acquisition
Land	(97)
Building & Improvements	41,911
Gross Amount at Which Carried at Close of Period
Land	90,941
Building & Improvements	422,655
Total	513,596
Accumulated Depreciation	124,638
100 Summit Lake Drive
Real Estate And Accumulated Depreciation
Encumbrances	0
Initial Cost
Land	10,526
Building & Improvements	43,109
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	11,215
Gross Amount at Which Carried at Close of Period
Land	10,526
Building & Improvements	54,324
Total	64,850
Accumulated Depreciation	16,963
200 Summit Lake Drive
Real Estate And Accumulated Depreciation
Encumbrances	0
Initial Cost
Land	11,183
Building & Improvements	47,906
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	11,177
Gross Amount at Which Carried at Close of Period
Land	11,183
Building & Improvements	59,083
Total	70,266
Accumulated Depreciation	18,818
500 Summit Lake Drive
Real Estate And Accumulated Depreciation
Encumbrances	0
Initial Cost
Land	9,777
Building & Improvements	39,048
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	6,358
Gross Amount at Which Carried at Close of Period
Land	9,777
Building & Improvements	45,406
Total	55,183
Accumulated Depreciation	13,074
360 Hamilton Avenue
Real Estate And Accumulated Depreciation
Encumbrances	0
Initial Cost
Land	29,497
Building & Improvements	118,250
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	15,392
Gross Amount at Which Carried at Close of Period
Land	29,497
Building & Improvements	133,642
Total	163,139
Accumulated Depreciation	39,811
1010 Washington Boulevard
Real Estate And Accumulated Depreciation
Encumbrances	0
Initial Cost
Land	7,747
Building & Improvements	30,423
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	7,378
Gross Amount at Which Carried at Close of Period
Land	7,747
Building & Improvements	37,801
Total	45,548
Accumulated Depreciation	11,044
1055 Washington Boulevard
Real Estate And Accumulated Depreciation
Encumbrances	0
Initial Cost
Land	13,516
Building & Improvements	53,228
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	8,390
Gross Amount at Which Carried at Close of Period
Land	13,516
Building & Improvements	61,618
Total	75,134
Accumulated Depreciation	18,075
400 Summit Lake Drive
Real Estate And Accumulated Depreciation
Encumbrances	0
Initial Cost
Land	38,889
Building & Improvements	1
Cost Capitalized Subsequent To Acquisition
Land	285
Building & Improvements	3
Gross Amount at Which Carried at Close of Period
Land	39,174
Building & Improvements	4
Total	39,178
Accumulated Depreciation	0
609 Fifth Avenue
Real Estate And Accumulated Depreciation
Encumbrances	0
Initial Cost
Land	36,677
Building & Improvements	145,954
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	10,435
Gross Amount at Which Carried at Close of Period
Land	36,677
Building & Improvements	156,389
Total	193,066
Accumulated Depreciation	46,059
110 East 42nd Street
Real Estate And Accumulated Depreciation
Encumbrances	0
Initial Cost
Land	34,000
Building & Improvements	46,411
Cost Capitalized Subsequent To Acquisition
Land	(138)
Building & Improvements	23,984
Gross Amount at Which Carried at Close of Period
Land	33,862
Building & Improvements	70,395
Total	104,257
Accumulated Depreciation	17,244
304 Park Avenue South
Real Estate And Accumulated Depreciation
Encumbrances	0
Initial Cost
Land	54,189
Building & Improvements	75,619
Cost Capitalized Subsequent To Acquisition
Land	300
Building & Improvements	14,550
Gross Amount at Which Carried at Close of Period
Land	54,489
Building & Improvements	90,169
Total	144,658
Accumulated Depreciation	16,445
635 Sixth Avenue
Real Estate And Accumulated Depreciation
Encumbrances	0
Initial Cost
Land	24,180
Building & Improvements	37,158
Cost Capitalized Subsequent To Acquisition
Land	163
Building & Improvements	51,805
Gross Amount at Which Carried at Close of Period
Land	24,343
Building & Improvements	88,963
Total	113,306
Accumulated Depreciation	7,854
641 Sixth Avenue
Real Estate And Accumulated Depreciation
Encumbrances	0
Initial Cost
Land	45,668
Building & Improvements	67,316
Cost Capitalized Subsequent To Acquisition
Land	308
Building & Improvements	6,029
Gross Amount at Which Carried at Close of Period
Land	45,976
Building & Improvements	73,345
Total	119,321
Accumulated Depreciation	12,097
315 West 33rd Street
Real Estate And Accumulated Depreciation
Encumbrances	250,000
Initial Cost
Land	195,834
Building & Improvements	164,429
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	11,583
Gross Amount at Which Carried at Close of Period
Land	195,834
Building & Improvements	176,012
Total	371,846
Accumulated Depreciation	19,966
Williamsburg
Real Estate And Accumulated Depreciation
Encumbrances	0
Initial Cost
Land	3,677
Building & Improvements	14,708
Cost Capitalized Subsequent To Acquisition
Land	2,523
Building & Improvements	(4,550)
Gross Amount at Which Carried at Close of Period
Land	6,200
Building & Improvements	10,158
Total	16,358
Accumulated Depreciation	1,865
115 Spring Street
Real Estate And Accumulated Depreciation
Encumbrances	0
Initial Cost
Land	11,078
Building & Improvements	44,799
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	1,759
Gross Amount at Which Carried at Close of Period
Land	11,078
Building & Improvements	46,558
Total	57,636
Accumulated Depreciation	4,083
635 Madison Avenue
Real Estate And Accumulated Depreciation
Encumbrances	0
Initial Cost
Land	205,632
Building & Improvements	15,805
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	0
Gross Amount at Which Carried at Close of Period
Land	205,632
Building & Improvements	15,805
Total	221,437
Accumulated Depreciation	1,306
125 Park Avenue
Real Estate And Accumulated Depreciation
Encumbrances	0
Initial Cost
Land	120,900
Building & Improvements	189,714
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	74,660
Gross Amount at Which Carried at Close of Period
Land	120,900
Building & Improvements	264,374
Total	385,274
Accumulated Depreciation	65,529
625 Madison Avenue
Real Estate And Accumulated Depreciation
Encumbrances	0
Initial Cost
Land	0
Building & Improvements	246,673
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	43,175
Gross Amount at Which Carried at Close of Period
Land	0
Building & Improvements	289,848
Total	289,848
Accumulated Depreciation	107,791
711 Third Avenue
Real Estate And Accumulated Depreciation
Encumbrances	0
Initial Cost
Land	19,844
Building & Improvements	42,499
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	66,553
Gross Amount at Which Carried at Close of Period
Land	19,844
Building & Improvements	109,052
Total	128,896
Accumulated Depreciation	$ 39,396
Interest in property (as a percent)	50.00%
752 Madison Avenue
Real Estate And Accumulated Depreciation
Encumbrances	$ 0
Initial Cost
Land	282,415
Building & Improvements	0
Cost Capitalized Subsequent To Acquisition
Land	1,871
Building & Improvements	0
Gross Amount at Which Carried at Close of Period
Land	284,286
Building & Improvements	0
Total	284,286
Accumulated Depreciation	12
110 Greene Street
Real Estate And Accumulated Depreciation
Encumbrances	0
Initial Cost
Land	45,120
Building & Improvements	215,470
Cost Capitalized Subsequent To Acquisition
Land	0
Building & Improvements	9,611
Gross Amount at Which Carried at Close of Period
Land	45,120
Building & Improvements	225,081
Total	270,201
Accumulated Depreciation	$ 15,693
Interest in property (as a percent)	90.00%
Other
Real Estate And Accumulated Depreciation
Encumbrances	$ 0
Initial Cost
Land	1,130
Building & Improvements	0
Cost Capitalized Subsequent To Acquisition
Land	(1,135)
Building & Improvements	4,694
Gross Amount at Which Carried at Close of Period
Land	(5)
Building & Improvements	4,694
Total	4,689
Accumulated Depreciation	$ 1

Schedule III_Real Estate And 70

Schedule III—Real Estate And Accumulated Depreciation - Changes in Real Estate and Accumulated Depreciation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Changes in real estate
Balance at beginning of year	$ 7,508,870	$ 7,428,243	$ 7,203,216
Acquisitions	0	0	329,996
Improvements	121,959	123,173	93,439
Retirements/disposals	(601,374)	(42,546)	(198,408)
Balance at end of year	7,029,455	7,508,870	7,428,243
Aggregate cost of land, buildings and improvements, before depreciation, for Federal income tax purposes	4,600,000
Changes in accumulated depreciation, exclusive of amounts relating to equipment, autos, and furniture and fixtures
Balance at beginning of year	1,437,222	1,267,598	1,123,412
Depreciation for year	178,801	183,873	175,039
Retirements/disposals	(123,420)	(14,249)	(30,853)
Balance at end of year	$ 1,492,603	$ 1,437,222	$ 1,267,598