Tiaa Real Estate Account 10-Q 6 Nov 18 2018 Q3 Quarterly report Financial data

Document And Entity Information

Document And Entity Information	9 Months Ended
	Sep. 30, 2018shares
Document and Entity Information [Abstract]
Entity Registrant Name	TIAA REAL ESTATE ACCOUNT
Document Type	10-Q
Current Fiscal Year End Date	--12-31
Entity Common Stock, Shares Outstanding (in shares)	0
Amendment Flag	false
Entity Central Index Key	946,155
Entity Filer Category	Non-accelerated Filer
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Entity Current Reporting Status	Yes
Entity Small Reporting Company	false
Entity Emerging Growth Company	false

CONSOLIDATED STATEMENTS OF ASSE

CONSOLIDATED STATEMENTS OF ASSETS AND LIABILITIES - USD ($) shares in Millions, $ in Millions		Sep. 30, 2018	Dec. 31, 2017
Investments, at fair value:
Real estate properties (cost: $12,586.2 and $12,972.5)		$ 15,345.9	$ 15,742.7
Real estate joint ventures and limited partnerships (cost: $4,604.2 and $4,675.3)		5,936.2	6,003
Marketable securities:
Real estate-related (cost: $1,182.1 and $991.0)	[1]	1,430.6	1,238
Other (cost: $4,845.4 and $3,888.1)		4,844.7	3,887.5
Loans receivable (cost: $852.0 and $296.7)		855.1	298.8
Total investments (cost: $24,069.9 and $22,823.6)		28,412.5	27,170
Cash and cash equivalents		10.1	11.7
Due from investment manager		6.1	1
Other	[2]	249.1	270.9
TOTAL ASSETS		28,677.8	27,453.6
LIABILITIES
Mortgage loans payable, at fair value (principal outstanding: $2,797.9 and $2,238.6)		2,743.2	2,238.3
Accrued real estate property expenses		237.2	199.1
Payable for collateral for securities loaned		6.5	18.5
Other		56.8	55.1
TOTAL LIABILITIES		3,043.7	2,511
COMMITMENTS AND CONTINGENCIES
NET ASSETS
Accumulation Fund		25,112.7	24,430.8
Annuity Fund		521.4	511.8
TOTAL NET ASSETS		$ 25,634.1	$ 24,942.6
NUMBER OF ACCUMULATION UNITS OUTSTANDING (in shares)		60.7	61.3
NET ASSET VALUE, PER ACCUMULATION UNIT (in dollars per share)		$ 413.479	$ 398.329
[1]	Includes securities loaned of $6.4 million at September 30, 2018 and $18.1 million at December 31, 2017.
[2]	Includes cash collateral for securities loaned of $6.5 million at September 30, 2018 and $18.5 million at December 31, 2017.

CONSOLIDATED STATEMENTS OF AS_2

CONSOLIDATED STATEMENTS OF ASSETS AND LIABILITIES (Parenthetical) - USD ($) $ in Millions		Sep. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Securities loaned		$ 6.4	$ 18.1
Cash collateral for securities loaned		6.5	18.5
Restricted cash	[1]	45.1
Real estate properties at cost		12,586.2	12,972.5
Real estate joint ventures and limited partnerships at cost		4,604.2	4,675.3
Real estate-related Marketable securities at cost		1,182.1	991
Other Marketable securities at cost		4,845.4	3,888.1
Loans receivable at cost		852	296.7
Cost of Total investments		24,069.9	22,823.6
Principal outstanding on Mortgage loans payable		$ 2,797.9	$ 2,238.6
[1]	Restricted cash is included within other assets on the Account's Consolidated Statements of Assets and Liabilities.

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Real estate income, net:
Rental income	$ 273.3	$ 267.9	$ 822.7	$ 791.6
Real estate property level expenses and taxes:
Operating expenses	58.5	56.9	171.7	164.9
Real estate taxes	45.4	43.2	135.3	127.3
Interest expense	30.4	22.5	82.8	67.3
Total real estate property level expenses and taxes	134.3	122.6	389.8	359.5
Real estate income, net	139	145.3	432.9	432.1
Income from real estate joint ventures and limited partnerships	37.3	60.9	157.8	154.3
Interest	35.1	15.9	77.6	37.6
Dividends	14.7	7.9	36.7	15.7
TOTAL INVESTMENT INCOME	226.1	230	705	639.7
Expenses:
Investment management charges	13.9	15.5	46.3	52.9
Administrative charges	14.3	14.7	41	46
Distribution charges	6.8	6.4	20.8	19.6
Mortality and expense risk charges	0.3	0.3	0.9	0.9
Liquidity guarantee charges	12.8	12.5	37.5	34.5
TOTAL EXPENSES	48.1	49.4	146.5	153.9
INVESTMENT INCOME, NET	178	180.6	558.5	485.8
Net realized gain (loss) on investments:
Real estate properties	179.8	75.2	223.4	58.4
Real estate joint ventures and limited partnerships	56.8	(8.6)	57	(8.6)
Marketable securities	3.3	2.6	10.2	15.3
Net realized gain on investments	239.9	69.2	290.6	65.1
Net change in unrealized appreciation (depreciation) on:
Real estate properties	(65.2)	(9.4)	(10.5)	74.8
Real estate joint ventures and limited partnerships	(49.3)	26.9	43	88.7
Marketable securities	(6.4)	2.2	0.5	34.2
Loans receivable	1	1.4	1	1.4
Mortgage loans payable	(0.8)	(4.1)	54.4	(10.6)
Net change in unrealized appreciation (depreciation) on investments and mortgage loans payable	(120.7)	17	88.4	188.5
NET REALIZED AND UNREALIZED GAIN ON INVESTMENTS AND MORTGAGE LOANS PAYABLE	119.2	86.2	379	253.6
NET INCREASE IN NET ASSETS RESULTING FROM OPERATIONS	$ 297.2	$ 266.8	$ 937.5	$ 739.4

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN NET ASSETS - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
FROM OPERATIONS
Investment income, net	$ 178	$ 180.6	$ 558.5	$ 485.8
Net realized gain on investments	239.9	69.2	290.6	65.1
Net change in unrealized appreciation (depreciation) on investments and mortgage loans payable	(120.7)	17	88.4	188.5
NET INCREASE IN NET ASSETS RESULTING FROM OPERATIONS	297.2	266.8	937.5	739.4
FROM PARTICIPANT TRANSACTIONS
Premiums	648.2	552.4	1,920.9	1,980.6
Annuity payments	(11.2)	(10.8)	(33.6)	(32.3)
Withdrawals and death benefits	(600.6)	(777.5)	(2,133.3)	(2,152.6)
NET INCREASE (DECREASE) IN NET ASSETS RESULTING FROM PARTICIPANT TRANSACTIONS	36.4	(235.9)	(246)	(204.3)
NET INCREASE IN NET ASSETS	333.6	30.9	691.5	535.1
NET ASSETS
Beginning of period	25,300.5	24,808.9	24,942.6	24,304.7
End of period	$ 25,634.1	$ 24,839.8	$ 25,634.1	$ 24,839.8

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2018		Sep. 30, 2017	Sep. 30, 2018		Sep. 30, 2017
CASH FLOWS FROM OPERATING ACTIVITIES
Net increase in net assets resulting from operations	$ 297.2		$ 266.8	$ 937.5		$ 739.4
Adjustments to reconcile net changes in net assets resulting from operations to net cash (used in) provided by operating activities:
Net realized gain on investments	(239.9)		(69.2)	(290.6)		(65.1)
Net change in unrealized appreciation on investments and mortgage loans payable	120.7		(17)	(88.4)		(188.5)
Purchase of real estate properties				(542.2)		(298.4)
Capital improvements on real estate properties				(165.5)		(95)
Proceeds from sale of real estate properties				1,223.5		340.7
Purchases of long term investments				(644.5)		(342.5)
Proceeds from long term investments				629.5		376.3
Purchase of loans receivable				(699.6)		(1.7)
Proceeds from sales of loans receivable				78.7		0
Proceeds from payoffs of loans receivable				65.6		0
Increase in other investments				(957.3)		(239.3)
Change in due to (from) investment manager				(5.1)		1.1
Decrease in other assets				24.6		101
Decrease (increase) in other liabilities				10.3		(74.5)
NET CASH (USED IN) PROVIDED BY OPERATING ACTIVITIES				(423.5)		253.5
CASH FLOWS FROM FINANCING ACTIVITIES
Mortgage loan proceeds received				712.8		0
Payments of mortgage loans				(42.1)		(49.4)
Premiums	648.2		552.4	1,920.9		1,980.6
Annuity payments	(11.2)		(10.8)	(33.6)		(32.3)
Withdrawals and death benefits	(600.6)		(777.5)	(2,133.3)		(2,152.6)
NET CASH PROVIDED BY (USED IN) FINANCING ACTIVITIES				424.7		(253.7)
NET INCREASE (DECREASE) IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH				1.2		(0.2)
CASH, CASH EQUIVALENTS AND RESTRICTED CASH
Beginning of period cash, cash equivalents and restricted cash				54		48.8
Net increase (decrease) in cash, cash equivalents and restricted cash				1.2		(0.2)
TOTAL CASH, CASH EQUIVALENTS AND RESTRICTED CASH	55.2		48.6	55.2		48.6
SUPPLEMENTAL DISCLOSURES:
Cash paid for interest				80.1		67.3
Mortgage loan assumed as part of real estate acquisition				105.1		17.7
Mortgage loan assignment as part of real estate disposition				(216.5)		0
Stock consideration received from the disposition of marketable securities				6.1		0
Cash and cash equivalents	10.1		6.8	10.1		6.8
Restricted cash	45.1	[1]	41.8	45.1	[1]	41.8
TOTAL CASH, CASH EQUIVALENTS AND RESTRICTED CASH	$ 55.2		$ 48.6	$ 55.2		$ 48.6
[1]	Restricted cash is included within other assets on the Account's Consolidated Statements of Assets and Liabilities.

Organization and Significant Ac

Organization and Significant Accounting Policies	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Organization and Significant Accounting Policies	Organization and Significant Accounting Policies Business: The TIAA Real Estate Account (“Account”) is an insurance separate account of Teachers Insurance and Annuity Association of America (“TIAA”) and was established by resolution of TIAA’s Board of Trustees (the “Board”) on February 22, 1995, under the insurance laws of the State of New York, for the purpose of funding variable annuity contracts issued by TIAA. The Account offers individual and group accumulating annuity contracts (with contributions made on a pre-tax or after-tax basis), as well as individual lifetime and term-certain variable payout annuity contracts (including the payment of death benefits to beneficiaries). Investors are entitled to transfer funds to or from the Account, and make withdrawals from the Account on a daily basis, under certain circumstances. Funds invested in the Account for each category of contract are expressed in terms of units, and unit values will fluctuate depending on the Account’s performance. The investment objective of the Account is to seek favorable total returns primarily through the rental income and appreciation of a diversified portfolio of directly held, private real estate investments and real estate-related investments while offering investors guaranteed, daily liquidity. The Account holds real estate properties directly and through subsidiaries wholly-owned by TIAA for the sole benefit of the Account. The Account also holds limited interests in real estate joint ventures and limited partnerships, as well as investments in loans receivable with commercial real estate properties as underlying collateral. Additionally, the Account invests in real estate-related and non-real estate-related publicly traded securities, cash and other instruments to maintain adequate liquidity levels for operating expenses, capital expenditures and to fund benefit payments (withdrawals, transfers and related transactions). The Consolidated Financial Statements were prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP"), which requires the use of estimates made by management. Actual results may vary from those estimates and such differences may be material. The Consolidated Financial Statements of the Account as of September 30, 2018 and for the three and nine months ended September 30, 2018 and 2017 are unaudited and include all adjustments necessary to present a fair statement of results for the interim periods presented. Results of operations for the interim periods are not necessarily indicative of results for the entire year. These Consolidated Financial Statements have been prepared in accordance with the applicable rules and regulations of the Securities and Exchange Commission (“SEC”). Accordingly, certain footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted from this report pursuant to the rules of the SEC. As a result, these Consolidated Financial Statements should be read in conjunction with the audited Consolidated Financial Statements and notes thereto for the year ended December 31, 2017 included in the Account’s 2017 annual report on Form 10-K. The following is a summary of the significant accounting policies of the Account. Basis of Presentation: The accompanying Consolidated Financial Statements include the Account and those subsidiaries wholly-owned by TIAA for the sole benefit of the Account. All significant intercompany accounts and transactions between the Account and such subsidiaries have been eliminated. The Accumulation Unit Value (“AUV”) used for financial reporting purposes may differ from the AUV used for processing transactions. The AUV used for financial reporting purposes includes security and participant transactions effective through the period end date to which this report relates. Total return is computed based on the AUV used for processing transactions. Determination of Investments at Fair Value: The Account reports all investments at fair value in accordance with the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 946, Financial Services—Investment Companies. Further in accordance with the adoption of the fair value option allowed under ASC 825, Financial Instruments , and at the election of Account management, mortgage loans payable and a line of credit are reported at fair value. The FASB has defined 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 excluding transaction costs. The following is a description of the valuation methodologies used to determine the fair value of the Account’s investments and investment related mortgage loans payable. Valuation of Real Estate Properties —Investments in real estate properties are stated at fair value, as determined in accordance with policies and procedures reviewed by the Investment Committee of the Board and in accordance with the responsibilities of the Board as a whole. Accordingly, the Account does not record depreciation. Determination of fair value involves significant levels of judgment because the actual fair value of real estate can be determined only by negotiation between the parties in a sales transaction. The Account’s primary objective when valuing its real estate investments is to produce a valuation that represents a reasonable estimate of the fair value of its investments. Implicit in the Account’s definition of fair value are the consummation of a sale as of a specified date and the passing of title from seller to buyer under conditions whereby: • Buyer and seller are typically motivated; • Both parties are well informed or well advised, and acting in what they consider their best interests; • A reasonable time is allowed for exposure in the open market; • Payment is made in terms of cash or in terms of financial arrangements comparable thereto; and • The price represents the normal consideration for the property sold unaffected by special or creative financing or sales concessions granted by anyone associated with the sale. Property and investment values are affected by, among other things, the availability of capital, occupancy rates, rental rates, and interest and inflation rates. As a result, determining real estate and investment values involves many assumptions. Key inputs and assumptions include rental income and expense amounts, related rental income and expense growth rates, capital expenditures, discount rates and capitalization rates. Valuation techniques include discounted cash flow analysis, prevailing market capitalization rates or multiples applied to earnings from the property, analysis of recent comparable sales transactions, actual sale negotiations and bona fide purchase offers received from third parties. Amounts ultimately realized from each investment may vary significantly from the fair value presented. Real estate properties owned by the Account are initially valued based on an independent third party appraisal, as reviewed by TIAA’s internal appraisal staff and as applicable by the Account’s independent fiduciary at the time of the closing of the purchase. Such initial valuation may result in a potential unrealized gain or loss reflecting the difference between an investment’s fair value (i.e., exit price) and its cost basis (which is inclusive of transaction costs). Subsequently, each property is appraised each quarter by an independent third party appraiser, reviewed by TIAA’s internal appraisal staff and as applicable the Account’s independent fiduciary. In general, the Account obtains appraisals of its real estate properties spread out throughout the quarter, which is intended to result in appraisal adjustments, and thus, adjustments to the valuations of its holdings (to the extent such adjustments are made) that happen regularly throughout each quarter and not on one specific day or month in each period. Further, management reserves the right to order an appraisal and/or conduct another valuation outside of the normal quarterly process when facts or circumstances at a specific property change. For example, under certain circumstances a valuation adjustment could be made when the account receives a bona fide bid for the sale of a property held within the Account or one of the Account’s joint ventures. Adjustments may be made for events or circumstances indicating an impairment of a tenant’s ability to pay amounts due to the Account under a lease (including due to a bankruptcy filing of that tenant). Alternatively, adjustments may be made to reflect the execution or renewal of a significant lease. Also, adjustments may be made to reflect factors (such as sales values for comparable properties or local employment rate) bearing uniquely on a particular region in which the Account holds properties. TIAA’s internal appraisal staff oversees the entire appraisal process, in conjunction with the Account’s independent fiduciary (the independent fiduciary is more fully described in the following paragraph). Any differences in the conclusions of TIAA’s internal appraisal staff and the independent appraiser will be reviewed by the independent fiduciary, which will make a final determination on the matter (which may include ordering a subsequent independent appraisal). The independent fiduciary, RERC, LLC, was initially appointed in March 2006 by a special subcommittee of the Investment Committee of the Board to, among other things, oversee the entire appraisal process. In March 2018, RERC, LLC, was re-appointed as the Account's independent fiduciary for a term expiring in February 2021. The independent fiduciary must approve all independent appraisers used by the Account. All appraisals are performed in accordance with Uniform Standards of Professional Appraisal Practices, the real estate appraisal industry standards created by The Appraisal Foundation. Real estate appraisals are estimates of property values based on a professional’s opinion. Appraisals of properties held outside of the U.S. are performed in accordance with industry standards commonly applied in the applicable jurisdiction. These independent appraisers are always expected to be MAI-designated members of the Appraisal Institute (or its European equivalent, Royal Institute of Chartered Surveyors) and state certified appraisers from national or regional firms with relevant property type experience and market knowledge. Under the Account’s current procedures, each independent appraisal firm will be rotated off of a particular property at least every three years, although such appraisal firm may perform appraisals of other Account properties subsequent to such rotation. Also, the independent fiduciary may require additional appraisals if factors or events have occurred that could materially change a property’s value (including those identified previously) and such change is not reflected in the quarterly valuation review, or otherwise to ensure that the Account is valued appropriately. The independent fiduciary must also approve any valuation change of real estate-related assets where a property’s value changed by more than 6% from the most recent independent annual appraisal, or if the value of the Account would change by more than 4% within any calendar quarter or more than 2% since the prior calendar month. When a real estate property is subject to a mortgage, the property is valued independently of the mortgage and the property and mortgage fair values are reported separately (see Valuation of Mortgage Loans Payable ). The independent fiduciary reviews and approves all mortgage valuation adjustments before such adjustments are recorded by the Account. The Account continues to use the revised value for each real estate property and mortgage loan payable to calculate the Account’s daily net asset value until the next valuation review or appraisal. Valuation of Real Estate Joint Ventures —Real estate joint ventures are stated at the fair value of the Account’s ownership interests of the underlying entities. The Account’s ownership interests are valued based on the fair value of the underlying real estate, any related mortgage loans payable, and other factors, such as ownership percentage, ownership rights, buy/sell agreements, distribution provisions and capital call obligations. Upon the disposition of all real estate investments by an investee entity, the Account will continue to state its equity in the remaining net assets of the investee entity during the wind down period, if any, which occurs prior to the dissolution of the investee entity. Valuation of Real Estate Limited Partnerships —Limited partnership interests are stated at the fair value of the Account’s ownership in the partnership, with fair value defined as the net asset value. The Account receives net asset values from limited partners on a quarterly basis. Upon receipt, TIAA's internal appraisal staff review such information and conclude on whether the net asset values provided are an appropriate representation of the fair value of the Account's interests in the limited partnerships. Since market quotations or values from independent pricing services are not readily available or are not considered reliable, the limited partnership interests are valued at fair value as determined in good faith by management under the direction of the Investment Committee of the Board and in accordance with the responsibilities of the Board as a whole. Valuation of Marketable Securities —Equity securities listed or traded on any national market or exchange are valued at the last sale price as of the close of the principal securities market or exchange on which such securities are traded or, if there is no sale, at the mean of the last bid and asked prices on such market or exchange, exclusive of transaction costs. Valuation of Debt Securities —Debt securities with readily available market quotations, other than money market instruments, are generally valued at the most recent bid price or the equivalent quoted yield for such securities (or those of comparable maturity, quality and type). Debt securities for which market quotations or values from independent pricing services are not readily available or are not considered reliable, are valued at fair value as determined in good faith by management under the direction of the Investment Committee of the Board and in accordance with the responsibilities of the Board as a whole. Short-term investments are valued in the same manner as debt securities, as described above. Money market instruments are valued at amortized cost, which approximates fair value. Valuation of Loans Receivable (i.e., the Account as a creditor) —Loans receivable are stated at fair value and are initially valued at the face amount of the loan funding. Subsequently, loans receivable are valued at least quarterly by TIAA’s internal valuation department based on market factors, such as market interest rates and spreads for comparable loans, the liquidity for loans of similar characteristics, the performance of the underlying collateral (such as the loan-to-value ratio and the cash flow of the underlying collateral) and the credit quality of the counterparty. The independent fiduciary reviews and approves all loan receivable valuation adjustments before such adjustments are recorded by the Account. Valuation of Mortgage Loans Payable and Line of Credit (i.e., the Account as a debtor) —Mortgage loans payable and the Account's unsecured revolving line of credit (collectively "Debt") are stated at fair value. The estimated fair values of Debt are based on the amount at which Debt could be transferred to a third party exclusive of transaction costs. Debt is valued internally by TIAA’s internal valuation department, as reviewed by the Account’s independent fiduciary, at least quarterly based on market factors, such as market interest rates and spreads for comparable loans, the performance of the underlying collateral (such as the loan-to-value ratio and the cash flow of the underlying collateral), the liquidity for mortgage loans of similar characteristics, the maturity date of the loan, the credit quality of the Account and the return demands of the market. See Note 4 — Assets and Liabilities Measured at Fair Value on a Recurring Basis for further discussion and disclosure regarding the determination of the fair value of the Account’s investments. Accumulation and Annuity Funds: The accumulation fund represents the net assets attributable to participants in the accumulation phase of their investment (“Accumulation Fund”). The annuity fund represents the net assets attributable to the participants currently receiving annuity payments (“Annuity Fund”). The net increase or decrease in net assets from investment operations is apportioned between the funds based upon their relative daily net asset values. Once an Account participant begins receiving lifetime annuity income benefits, payment levels cannot be reduced as a result of the Account’s actual mortality experience. In addition, the contracts pursuant to which the Account is offered are required to stipulate the maximum expense charge for all Account level expenses that can be assessed, which is not to exceed 2.5% of average net assets per year. The Account pays a fee to TIAA to assume mortality and expense risks. Accounting for Investments: The investments held by the Account are accounted for as follows: Real Estate Properties —Rent from real estate properties consists of all amounts earned under tenant leases, including base rent, recoveries of real estate taxes and other expenses and charges for miscellaneous services provided to tenants. Rental income is recognized in accordance with the billing terms of the lease agreements. The Account bears the direct expenses of the real estate properties owned. These expenses include, but are not limited to, fees to local property management companies, property taxes, utilities, maintenance, repairs, insurance, and other operating and administrative costs. An estimate of the net operating income earned from each real estate property is accrued by the Account on a daily basis and such estimates are adjusted when actual operating results are determined. Real Estate Joint Ventures —The Account has ownership interests in various real estate joint ventures (collectively, the “joint ventures”). The Account records its contributions as increases to its investments in the joint ventures, and distributions from the joint ventures are treated as income within income from real estate joint ventures and limited partnerships in the Account’s Consolidated Statements of Operations. Distributions that are identified as returns of capital are recorded as a reduction to the cost basis of the investment, whereas distributions identified as capital gains or losses are recorded as realized gains or losses. Income distributions from the joint ventures are recorded based on the Account’s proportional interest of the income distributed by the joint ventures. Income and losses incurred but not yet distributed or realized from the Account by the joint ventures are recorded as unrealized gains and losses. Limited Partnerships —The Account has ownership interests in various private real estate funds (primarily limited partnerships) and a private real estate investment trust (collectively, the “limited partnerships”). The Account records its contributions as increases to the investments, and distributions from the investments are treated as income within income from real estate joint ventures and limited partnerships in the Account’s Consolidated Statements of Operations. Distributions that are identified as returns of capital are recorded as a reduction to the cost basis of the investment, whereas distributions identified as capital gains or losses are recorded as realized gains or losses. Unrealized gains and losses are recorded based upon the changes in the net asset values of the limited partnerships as determined from the financial statements of the limited partnerships when received by the Account. Prior to the receipt of the financial statements from the limited partnerships, the Account estimates the value of its interest in good faith and will from time to time seek input from the issuer or the sponsor of the investments. Changes in value based on such estimates are recorded by the Account as unrealized gains and losses. Marketable Securities —Transactions in marketable securities are accounted for as of the date the securities are purchased or sold (trade date). Interest income is recorded as earned. Dividend income is recorded on the ex-dividend date within dividend income. Dividends that are identified as returns of capital are recorded as a reduction to the cost basis of the investment, whereas dividends identified as capital gains or losses are recorded as realized gains or losses. Realized gains and losses on securities transactions are accounted for on the specific identification method. Loans Receivable —The Account has ownership interests in loans receivable. Loans receivable are stated at fair value and are initially valued at the face amount of the loan funding. Subsequently, loans receivable are valued at least quarterly by TIAA’s internal valuation department with changes in fair value flowing through unrealized gain (loss). Interest income from loans receivable is recognized in accordance with the terms of the loans. Realized and Unrealized Gains and Losses —Realized gains and losses are recorded at the time an investment is sold or a distribution is received in relation to an investment sale from a joint venture or limited partnership. Real estate transactions are accounted for as of the date on which the purchase or sale transactions for the real estate properties close (settlement date). The Account recognizes a realized gain on the sale of a real estate property to the extent that the contract sales price exceeds the cost-to-date of the property being sold. A realized loss occurs when the cost-to-date exceeds the sales price. Realized gains and losses from partial sales of non-financial assets are recognized in accordance with ASC 610-20 - Gains and Losses from the Derecognition of Nonfinancial Assets . Unrealized gains and losses are recorded as the fair values of the Account’s investments are adjusted, and as discussed within the Real Estate Joint Ventures and Limited Partnerships sections above. Net Assets —The Account’s net assets as of the close of each valuation day are valued by taking the sum of: • the value of the Account’s cash, cash equivalents, and short-term and other debt instruments; • the value of the Account’s other securities and other non-real estate assets; • the value of the individual real properties (based on the most recent valuation of that property) and other real estate-related investments owned by the Account; • an estimate of the net operating income accrued by the Account from its properties, other real estate-related investments and non-real estate-related investments (including short-term marketable securities) since the end of the prior valuation day; and • actual net operating income earned from the Account’s properties, other real estate-related investments and non-real estate-related investments (but only to the extent any such item of income differs from the estimated income accrued for on such investments), and then reducing the sum by liabilities held within the Account, including the daily investment management fee, administration and distribution fees, mortality and expense fees, and the liquidity guarantee fee, and certain other expenses attributable to operating the Account. Daily estimates of net operating income are adjusted to reflect actual net operating income on a monthly basis, at which time such adjustments (if any) are reflected in the Account’s unit value. After the end of every quarter, the Account reconciles the amount of expenses deducted from the Account (which is established in order to approximate the costs that the Account will incur) with the expenses the Account actually incurred. If there is a difference, the Account adds it to or deducts it from the Account in equal daily installments over the remaining days of the following quarter. Material differences may be repaid in the current calendar quarter. The Account’s at cost deductions are based on projections of Account assets and overall expenses, and the size of any adjusting payments will be directly affected by the difference between management’s projections and the Account’s actual assets or expenses. Cash and Cash Equivalents: Cash and cash equivalents are balances held by the Account in bank deposit accounts which, at times, exceed federally insured limits. The Account’s management monitors these balances to mitigate the exposure of risk due to concentration and has not experienced any losses from such concentration. Other Assets and Other Liabilities: Other assets and other liabilities consist of operating assets and liabilities incurred and held at each individual real estate property investment. Other assets consist of, among other items, cash, tenant receivables and prepaid expenses; whereas other liabilities primarily consist of accrued real estate taxes and security deposits. Other assets also include cash collateral held for securities on loan. Federal Income Taxes: Based on provisions of the Internal Revenue Code, Section 817, the Account is taxed as a segregated asset account of TIAA and as such, the Account incurs no material federal income tax attributable to the net investment activity of the Account. The Account’s federal income tax return is generally subject to examination for a period of three years after it is filed. State and local tax returns may be subject to examination for an additional period of time depending on the jurisdiction. Management has analyzed the Account’s tax positions taken for all open federal income tax years and has concluded that no provision for federal income tax is required in the Account’s Consolidated Financial Statements. Restricted Cash: The Account held restricted cash in escrow accounts for security deposits, as required by certain states, as well as property taxes, insurance, and various other property related matters as required by certain creditors related to outstanding mortgage loans payable collateralized by certain real estate investments. These amounts are recorded within other assets on the Consolidated Statements of Assets and Liabilities. See Note 7—Mortgage Loans Payable for additional information regarding the Account’s outstanding mortgage loans payable. Changes in Net Assets: Premiums include premiums paid by existing accumulation unit holders in the Account and transfers into the Account. Withdrawals and death benefits include withdrawals out of the Account which include transfers out of the Account and required minimum distributions. Due to/from Investment Manager: Due to/from investment manager represents amounts that are to be paid or received by TIAA on behalf of the Account. Amounts generally are paid or received by the Account within one or two business days and no interest is contractually charged on these amounts. Securities Lending: The Account may lend securities to qualified borrowers to earn additional income. The Account receives cash collateral against the loaned securities and maintains cash collateral in an amount not less than 100% of the market value of loaned securities during the period of the loan; any additional collateral required due to changes in security values is delivered to the Account the next business day. Cash collateral received by the Account is invested exclusively in an interest-bearing deposit account. The value of the loaned securities and the liability to return the cash collateral received are reflected in the Consolidated Statements of Assets and Liabilities. When loaning securities, the Account retains the benefits of owning the securities, including the economic equivalent of dividends or interest generated by the securities. All income generated by the securities lending program is reflected within interest income on the Consolidated Statements of Operations. As of September 30, 2018 , securities lending transactions are for real-estate related equity securities, and the resulting loans are continuous, can be recalled at any time, and have no set maturity. Securities lending income recognized by the Account consists of interest earned on cash collateral and lending fees, net of any rebates to the borrower and compensation to the agent. Such income is reflected within interest income on the Consolidated Statements of Operations. In lending its securities, the Account bears the market risk with respect to the investment of collateral and the risk that the agent may default on its contractual obligations to the Account. The agent bears the risk that the borrower may default on its obligation to return the loaned securities as the agent is contractually obligated to indemnify the Account if at the time of a default by a borrower some or all of the loan securities have not been returned. New Accounting Pronouncements In May 2014, the FASB issued Accounting Standard Update 2014-09, Revenue from Contracts with Customers (“ASU 2014-09”). ASU 2014-09 supersedes all existing revenue recognition guidance and establishes a five-step model to measure and recognize revenue. ASU 2014-09 was effective for fiscal years beginning after December 15, 2017 and the Account adopted this guidance as of January 1, 2018 utilizing the modified retrospective adoption approach. Under this approach, ASU 2014-09 was applied to all contracts that were not completed as of the date of adoption. Based on the Accounts implementation procedures, the adoption of ASU 2014-09 had an immaterial impact to the Account. In February 2016, the FASB issued Accounting Standards Update 2016-02 Leases (Topic 842) (“ASU 2016-02”) which will supersede Topic 840, Leases. This ASU applies to all entities that enter into a lease. Lessees will be required to report assets and liabilities that arise from leases. Lessor accounting is expected to remain unchanged; however, certain refinements were made to conform with the recently issued revenue recognition guidance in ASU 2014-09, specifically related to the allocation and recognition of contract consideration earned from lease and non-lease revenue components. The ASU contains certain practical expedients, which the Account plans to elect. The Account is electing the transition package of practical expedients permitted within the new standard. This practical expedient permits the Account to carryforward the historical lease classification and not to reassess initial direct costs for any existing leases. Further, the Account will initially apply the new lease requirements at the effective date of January 1, 2019, and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. In addition, the Account plans to elect the practical expedient that allows lessors to avoid separating lease and non-lease components within a contract if certain criteria are met. The lessor’s practical expedient election would be limited to circumstances in which (i) the timing and pattern of revenue recognition are the same for the non-lease component and the related lease component and (ii) the combined single lease component would be classified as an operating lease. This practical expedient would allow the Account the ability to combine the lease and non-lease components if the underlying asset meets the two criteria above. This ASU is effective for public business entities for fiscal years beginning after December 15, 2018, including all interim periods within those fiscal years. Management has completed its initial scoping for the adoption of the ASU 2016-02 and does not expect the adoption of such guidance to materially impact the Account. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement: Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurements. ASU 2018-13 modifies the disclosures required for fair value measurements. This guidance is effective for fiscal years beginning after December 15, 2019. Management is currently evaluating the impact of this guidance but does not expect it to materially impact the Account's Notes to the Consolidated Financial Statements.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2018
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Investment management, administrative and distribution services are provided to the Account at cost by TIAA. Services provided at cost are paid by the Account on a daily basis based upon projected expenses to be provided to the Account. Payments are adjusted periodically to ensure daily payments are as close as possible to the Account’s actual expenses incurred. Differences between actual expenses and the amounts paid by the Account are reconciled and adjusted quarterly. Investment management services for the Account are provided by TIAA officers, under the direction and control of the Board, pursuant to investment management procedures adopted by TIAA for the Account. TIAA’s investment management decisions for the Account are subject to review by the Account’s independent fiduciary. TIAA also provides various portfolio accounting and related services for the Account. The Account is a party to the Distribution Agreement for the Contracts Funded by the TIAA Real Estate Account (the “Distribution Agreement”), dated January 1, 2008, by and among TIAA, for itself and on behalf of the Account, and TIAA-CREF Individual and Institutional Services, LLC (“Services”), a wholly-owned subsidiary of TIAA and a registered broker-dealer and a member of the Financial Industry Regulatory Authority. Pursuant to the Distribution Agreement, Services performs distribution services for the Account which include, among other things, (i) distributing of annuity contracts issued by TIAA and funded by the Account, (ii) advising existing annuity contract owners in connection with their accumulations and (iii) helping employers implement and manage retirement plans. In addition, TIAA performs administrative functions for the Account, which include, among other things, (i) maintaining accounting records and performing accounting services, (ii) receiving and allocating premiums, (iii) calculating and making annuity payments, (iv) processing withdrawal requests, (v) providing regulatory compliance and reporting services, (vi) maintaining the Account’s records of contract ownership and (vii) otherwise assisting generally in all aspects of the Account’s operations. Both distribution services (pursuant to the Distribution Agreement) and administrative services are provided to the Account by Services and TIAA, as applicable, on an at cost basis. The Distribution Agreement is terminable by either party upon 60 days written notice and terminates automatically upon any assignment thereof. In addition to providing the services described above, TIAA charges the Account fees to bear certain mortality and expense risks, and risks with providing the liquidity guarantee. These fees are charged as a percentage of the net assets of the Account. Rates for these fees are established annually. Once an Account participant begins receiving lifetime annuity income benefits, payment levels cannot be reduced as a result of the Account’s actual mortality experience. As such, mortality and expense risk expenses are contractual charges for TIAA’s assumption of this risk. The liquidity guarantee ensures that sufficient funds are available to meet participant transfer and cash withdrawal requests in the event that the Account’s cash flows and liquid investments are insufficient to fund such requests. Expenses for the services and fees described above are identified as such in the accompanying Consolidated Statements of Operations and are further identified as "Expenses" in Note 9—Financial Highlights.

Concentrations of Risk

Concentrations of Risk	9 Months Ended
	Sep. 30, 2018
Risks and Uncertainties [Abstract]
Concentrations of Risk	Concentrations of Risk Concentrations of risk may arise when a number of properties are located in a similar geographic region such that the economic conditions of that region could impact tenants’ obligations to meet their contractual obligations or cause the values of individual properties to decline. Additionally, concentrations of risk may arise if any one tenant comprises a significant amount of the Account's rent, or if tenants are concentrated in a particular industry. As of September 30, 2018 , the Account had no significant concentrations of tenants as no single tenant had annual contract rent that made up more than 3% of the rental income of the Account. Moreover, the Account's tenants have no notable concentration present in any one industry. There are no significant lease expirations scheduled to occur over the next twelve months. The Account’s wholly-owned real estate investments and investments in joint ventures are located in the United States. The following table represents the diversification of the Account’s portfolio by region and property type as of September 30, 2018 (unaudited): Diversification by Fair Value (1) West East South Midwest Total Office 14.0 % 18.6 % 5.5 % — % 38.1 % Apartment 8.7 % 8.3 % 6.0 % 1.1 % 24.1 % Retail 8.1 % 3.1 % 7.8 % 0.7 % 19.7 % Industrial 8.1 % 1.7 % 4.4 % 0.5 % 14.7 % Other (2) 0.6 % 2.6 % 0.1 % 0.1 % 3.4 % Total 39.5 % 34.3 % 23.8 % 2.4 % 100.0 % (1) Wholly-owned properties are represented at fair value and gross of any debt, while joint venture properties are represented at the net equity value. (2) Represents interests in Storage Portfolio investments, a fee interest encumbered by a ground lease real estate investment and land. Properties in the “West” region are located in: AK, AZ, CA, CO, HI, ID, MT, NM, NV, OR, UT, WA, WY Properties in the “East” region are located in: CT, DC, DE, KY, MA, MD, ME, NC, NH, NJ, NY, PA, RI, SC, VA, VT, WV Properties in the “South” region are located in: AL, AR, FL, GA, LA, MS, OK, TN, TX Properties in the “Midwest” region are located in: IA, IL, IN, KS, MI, MN, MO, ND, NE, OH, SD, WI

Assets and Liabilities Measured

Assets and Liabilities Measured at Fair Value on a Recurring Basis	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured at Fair Value on a Recurring Basis	Assets and Liabilities Measured at Fair Value on a Recurring Basis Valuation Hierarchy: The Account’s fair value measurements are grouped categorically into three levels, as defined by the FASB. The levels are defined as follows: Level 1—Valuations using unadjusted quoted prices for assets traded in active markets, such as stocks listed on the New York Stock Exchange. Active markets are defined as having the following characteristics for the measured asset or liability: (i) many transactions, (ii) current prices, (iii) price quotes not varying substantially among market makers, (iv) narrow bid/ask spreads and (v) most information regarding the issuer is publicly available. Level 1 assets held by the Account are generally marketable equity securities. Level 2—Valuations for assets and liabilities traded in less active, dealer or broker markets. Fair values are primarily obtained from third party pricing services for identical or comparable assets or liabilities. Level 2 inputs for fair value measurements are inputs, other than quoted prices included within Level 1, that are observable for the asset or liability, either directly or indirectly. Level 2 inputs include: a. Quoted prices for similar assets or liabilities in active markets; b. Quoted prices for identical or similar assets or liabilities in markets that are not active (that is, markets in which there are few transactions for the asset (or liability), the prices are not current, price quotations vary substantially either over time or among market makers (for example, some brokered markets), or in which little information is released publicly); c. Inputs other than quoted prices that are observable within the market for the asset (or liability) (for example, interest rates and yield curves, implied volatilities, prepayment speeds, loss severities, credit risks, and default rates that are observable at commonly quoted intervals); and d. Inputs that are derived principally from or corroborated by observable market data by correlation or other means (for example, market-corroborated inputs). Examples of securities which may be held by the Account and included in Level 2 include certificates of deposit, commercial paper, government agency notes, variable notes, United States Treasury securities, and debt securities. Level 3—Valuations for assets and liabilities that are derived from other valuation methodologies, including pricing models, discounted cash flow models and similar techniques, and are not based on market exchange, dealer, or broker-traded transactions. Level 3 valuations incorporate certain assumptions and projections that are not observable in the market, and require significant professional judgment in determining the fair value assigned to such assets or liabilities. Examples of Level 3 assets and liabilities which may be held by the Account from time to time include investments in real estate, investments in joint ventures, and loans receivable and payable. An investment’s categorization within the valuation hierarchy described above is based upon the lowest level of input that is significant to the fair value measurement. The Account's limited partnership investments are valued using the net asset value per share as a practical expedient which are excluded from the valuation hierarchy. The Account’s determination of fair value is based upon quoted market prices, where available. If listed prices or quotes are not available, fair value is based upon vendor-provided, evaluated prices or internally developed models that primarily use market-based or independently sourced market data, including interest rate yield curves, market spreads, and currency rates. Valuation adjustments will be made to reflect changes in credit quality, counterparty’s creditworthiness, the Account’s creditworthiness, liquidity, and other observable and unobservable inputs that are applied consistently over time. The methods described above are considered to produce fair values that represent a good faith estimate of what an unaffiliated buyer in the marketplace would pay to purchase the asset or would receive to transfer the liability. Since fair value calculations involve significant professional judgment in the application of both observable and unobservable attributes, actual realizable values or future fair values may differ from amounts reported. Furthermore, while the Account believes its valuation methods are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments, while reasonable, could result in different estimates of fair value at the reporting date. As discussed in Note 1 — Organization and Significant Accounting Policies in more detail, the Account generally obtains independent third party appraisals on a quarterly basis; there may be circumstances in the interim in which the true realizable value of a property is not reflected in the Account’s daily net asset value calculation or in the Account’s periodic Consolidated Financial Statements. This disparity may be more apparent when the commercial and/or residential real estate markets experience an overall and possibly dramatic decline (or increase) in property values in a relatively short period of time between appraisals. The following tables show the major categories of assets and liabilities measured at fair value on a recurring basis as of September 30, 2018 (unaudited) and December 31, 2017 , using unadjusted quoted prices in active markets for identical assets (Level 1); significant other observable inputs (Level 2); and significant unobservable inputs (Level 3); and fair value using the practical expedient (in millions): Description Level 1: Quoted Prices in Active Markets for Identical Assets Level 2: Significant Other Observable Inputs Level 3: Significant Unobservable Inputs Fair Value Using Practical Expedient Total at Real estate properties $ — $ — $ 15,345.9 $ — $ 15,345.9 Real estate joint ventures — — 5,795.3 — 5,795.3 Limited partnerships — — — 140.9 140.9 Marketable securities: Real estate-related 1,430.6 — — — 1,430.6 Government agency notes — 2,560.7 — — 2,560.7 United States Treasury securities — 2,284.0 — — 2,284.0 Loans receivable — — 855.1 — 855.1 Total Investments at $ 1,430.6 $ 4,844.7 $ 21,996.3 $ 140.9 $ 28,412.5 Mortgage loans payable $ — $ — $ (2,743.2 ) $ — $ (2,743.2 ) Description Level 1: Quoted Prices in Active Markets for Identical Assets Level 2: Significant Other Observable Inputs Level 3: Significant Unobservable Inputs Fair Value Using Practical Expedient Total at December 31, 2017 Real estate properties $ — $ — $ 15,742.7 $ — $ 15,742.7 Real estate joint ventures — — 5,860.6 — 5,860.6 Limited partnerships — — — 142.4 142.4 Marketable securities: Real estate-related 1,238.0 — — — 1,238.0 Government agency notes — 2,872.3 — — 2,872.3 United States Treasury securities — 1,015.2 — — 1,015.2 Loans receivable — — 298.8 — 298.8 Total Investments at December 31, 2017 $ 1,238.0 $ 3,887.5 $ 21,902.1 $ 142.4 $ 27,170.0 Mortgage loans payable $ — $ — $ (2,238.3 ) $ — $ (2,238.3 ) The following tables show the reconciliation of the beginning and ending balances for assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) during the three and nine months ended September 30, 2018 and 2017 (in millions, unaudited): Real Estate Real Estate Loans Total Mortgage For the three months ended September 30, 2018 Beginning balance July 1, 2018 $ 16,042.7 $ 5,915.3 $ 618.3 $ 22,576.3 $ (2,891.4 ) Total realized and unrealized gains (losses) included in changes in net assets 114.6 7.5 1.0 123.1 (0.8 ) Purchases (1) 253.7 242.1 380.1 875.9 (72.0 ) Sales (1,065.1 ) — — (1,065.1 ) — Settlements (2) — (369.6 ) (144.3 ) (513.9 ) 221.0 Ending balance September 30, 2018 $ 15,345.9 $ 5,795.3 $ 855.1 $ 21,996.3 $ (2,743.2 ) Real Estate Real Estate Loans Total Mortgage For the nine months ended September 30, 2018 Beginning balance January 1, 2018 $ 15,742.7 $ 5,860.6 $ 298.8 $ 21,902.1 $ (2,238.3 ) Total realized and unrealized gains included in changes in net assets 212.9 99.1 1.0 313.0 54.4 Purchases (1) 830.3 325.9 699.6 1,855.8 (817.9 ) Sales (1,440.0 ) — — (1,440.0 ) — Settlements (2) — (490.3 ) (144.3 ) (634.6 ) 258.6 Ending balance September 30, 2018 $ 15,345.9 $ 5,795.3 $ 855.1 $ 21,996.3 $ (2,743.2 ) Real Estate Real Estate Loans Total Mortgage For the three months ended September 30, 2017 Beginning balance July 1, 2017 $ 15,496.6 $ 5,946.8 $ 297.3 $ 21,740.7 $ (2,290.1 ) Total realized and unrealized gains (losses) included in changes in net assets 65.8 17.6 1.4 84.8 (4.1 ) Purchases (1) 317.1 13.1 0.1 330.3 (17.7 ) Sales (225.3 ) — — (225.3 ) — Settlements (2) — (302.1 ) — (302.1 ) 0.9 Ending balance September 30, 2017 $ 15,654.2 $ 5,675.4 $ 298.8 $ 21,628.4 $ (2,311.0 ) Real Estate Real Estate Loans Total Mortgage For the nine months ended September 30, 2017 Beginning balance January 1, 2017 $ 15,452.8 $ 5,622.4 $ 295.7 $ 21,370.9 $ (2,332.1 ) Total realized and unrealized gains (losses) included in changes in net assets 133.2 80.4 1.4 215.0 (10.6 ) Purchases (1) 408.9 275.6 1.7 686.2 (17.7 ) Sales (340.7 ) — — (340.7 ) — Settlements (2) — (303.0 ) — (303.0 ) 49.4 Ending balance September 30, 2017 $ 15,654.2 $ 5,675.4 $ 298.8 $ 21,628.4 $ (2,311.0 ) (1) Includes purchases, contributions for joint ventures, capital expenditures, lending for loans receivable and assumption of mortgage loans payable. (2) Includes operating income for real estate joint ventures, net of distributions, principal payments and extinguishment of mortgage loans payable. The following table shows quantitative information about unobservable inputs related to the Level 3 fair value measurements as of September 30, 2018 (unaudited). Type Asset Class Valuation Unobservable Range (Weighted Average) Real Estate Properties and Joint Ventures Office Income Approach—Discounted Cash Flow Discount Rate 5.5% - 8.6% (6.5%) Income Approach—Direct Capitalization Overall Capitalization Rate 4.0% - 7.0% (4.9%) Industrial Income Approach—Discounted Cash Flow Discount Rate 5.5% - 8.9% (6.8%) Income Approach—Direct Capitalization Overall Capitalization Rate 4.0% - 7.5% (5.0%) Apartment Income Approach—Discounted Cash Flow Discount Rate 5.3% - 7.8% (6.3%) Income Approach—Direct Capitalization Overall Capitalization Rate 3.3% - 5.8% (4.5%) Retail Income Approach—Discounted Cash Flow Discount Rate 5.0% - 10.5% (6.4%) Income Approach—Direct Capitalization Overall Capitalization Rate 3.8% - 10.5% (4.6%) Mortgage Loans Payable Office and Industrial Discounted Cash Flow Loan to Value Ratio 37.7% - 70.7% (43.2%) Net Present Value Loan to Value Ratio 37.7% - 70.7% (43.2%) Apartment Discounted Cash Flow Loan to Value Ratio 32.3% - 63.9% (47.2%) Net Present Value Loan to Value Ratio 32.3% - 63.9% (47.2%) Retail Discounted Cash Flow Loan to Value Ratio 17.6% - 55.3% (33.2%) Net Present Value Loan to Value Ratio 17.6% - 55.3% (33.2%) Loans Receivable Office, Retail and Storage Discounted Cash Flow Loan to Value Ratio 70.8% - 79.2% (75.8%) The following table shows quantitative information about unobservable inputs related to the Level 3 fair value measurements as of September 30, 2017 (unaudited). Type Asset Class Valuation Unobservable Range (Weighted Average) Real Estate Properties and Joint Ventures Office Income Approach—Discounted Cash Flow Discount Rate 5.5% - 8.0% (6.5%) Income Approach—Direct Capitalization Overall Capitalization Rate 3.8% - 7.0% (4.8%) Industrial Income Approach—Discounted Cash Flow Discount Rate 5.5% - 8.5% (6.6%) Income Approach—Direct Capitalization Overall Capitalization Rate 4.0% - 7.5% (4.9%) Apartment Income Approach—Discounted Cash Flow Discount Rate 5.0% - 8.0% (6.1%) Income Approach—Direct Capitalization Overall Capitalization Rate 3.3% - 6.0% (4.3%) Retail Income Approach—Discounted Cash Flow Discount Rate 5.0% - 10.4% (6.4%) Income Approach—Direct Capitalization Overall Capitalization Rate 3.9% - 8.8% (4.6%) Mortgage Loans Payable Office and Industrial Discounted Cash Flow Loan to Value Ratio 38.0% - 70.0% (44.0%) Net Present Value Loan to Value Ratio 38.0% - 70.0% (44.0%) Apartment Discounted Cash Flow Loan to Value Ratio 28.1% - 65.6% (41.2%) Net Present Value Loan to Value Ratio 28.1% - 65.6% (41.2%) Retail Discounted Cash Flow Loan to Value Ratio 18.0% - 56.2% (32.9%) Net Present Value Loan to Value Ratio 18.0% - 56.2% (32.9%) Loans Receivable Office, Retail and Storage Discounted Cash Flow Loan to Value Ratio 60.1% - 74.5% (73.9%) Real Estate Properties and Joint Ventures: The significant unobservable inputs used in the fair value measurement of the Account’s real estate property and joint venture investments are the selection of certain investment rates (Discount Rate, Terminal Capitalization Rate, and Overall Capitalization Rate). Significant increases (decreases) in any of those inputs in isolation would result in significantly lower (higher) fair value measurements, respectively. Mortgage Loans Payable: The significant unobservable inputs used in the fair value measurement of the Account’s mortgage loans payable are the loan to value ratios and the selection of certain credit spreads and weighted average cost of capital risk premiums. Significant increases (decreases) in any of those inputs in isolation would result in a significantly lower (higher) fair value, respectively. Loans Receivable: The significant unobservable inputs used in the fair value measurement of the Account’s loans receivable are the loan to value ratios and the selection of certain credit spreads. Significant increases (decreases) in any of those inputs in isolation would result in a significantly lower (higher) fair value, respectively. During the nine months ended September 30, 2018 and 2017 , there were no transfers between Levels 1, 2 or 3. The amount of total net unrealized gains (losses) included in changes in net assets attributable to the change in net unrealized gains (losses) relating to Level 3 investments and mortgage loans payable using significant unobservable inputs still held as of the reporting date is as follows (in millions, unaudited): Real Estate Properties Real Estate Joint Ventures Loans Receivable Total Level 3 Investments Mortgage Loans Payable For the three months ended September 30, 2018 $ 48.1 $ (18.1 ) $ 1.1 $ 31.1 $ 4.8 For the nine months ended September 30, 2018 $ 158.8 $ 73.5 $ 1.1 $ 233.4 $ 60.0 For the three months ended September 30, 2017 $ 68.0 $ 17.9 $ 1.4 $ 87.3 $ (4.1 ) For the nine months ended September 30, 2017 $ 139.0 $ 80.7 $ 1.4 $ 221.1 $ (10.6 )

Investments in Joint Ventures

Investments in Joint Ventures	9 Months Ended
	Sep. 30, 2018
Equity Method Investments and Joint Ventures [Abstract]
Investments in Joint Ventures	Investments in Joint Ventures The Account owns interests in several real estate properties through joint ventures and receives distributions and allocations of profits and losses from the joint ventures based on the Account’s ownership interest in those investments. Several of these joint ventures have mortgage loans payable collateralized by the properties owned by the aforementioned joint ventures. At September 30, 2018 , the Account held investments in joint ventures with ownership interest percentages that ranged from 33.3% to 97.5% . Certain joint ventures are subject to adjusted distribution percentages when earnings in the investment reach a pre-determined threshold. The fair value of the Account’s equity interest in these joint ventures was $5.8 billion and $5.9 billion at September 30, 2018 and December 31, 2017 , respectively. A condensed summary of the results of operations of the joint ventures are shown below (in millions, unaudited): For the Three Months Ended September 30, For the Nine Months Ended September 30, 2018 2017 2018 2017 Operating Revenue and Expenses Revenues $ 237.2 $ 218.0 $ 694.2 $ 645.0 Expenses 122.8 108.3 381.0 315.0 Excess of revenues over expenses $ 114.4 $ 109.7 $ 313.2 $ 330.0

Investments in Limited Partners

Investments in Limited Partnerships	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Investments in Limited Partnerships	Investments in Limited Partnerships Clarion Gables Multi-Family Trust LP allows redemptions with an advanced notice of three months or more. Redemptions are funded using the partnership’s available cash, which may not immediately be in excess of the redemption amount, and may not be sufficient to fund the redemption amount for several months. The general partner has sole discretion in identifying how much cash is available to process redemptions. The partnership allows the Account to sell its interest in the partnership, subject to the consent and approval of the general partner. Taconic New York City GP Fund, LP prohibits redemptions in the partnership prior to liquidation. Liquidation of the partnership is estimated to begin no earlier than 2024. The partnership allows the Account to sell its interest in the partnership, subject to the consent and approval of the general partner. LCS SHIP Venture I, LLC prohibits redemptions prior to liquidation. The Account is generally not permitted to sell or transfer its interest in the company without consent of the manager.

Mortgage Loans Payable

Mortgage Loans Payable	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Mortgage Loans Payable	Mortgage Loans Payable At September 30, 2018 , the Account had outstanding mortgage loans payable secured by the following properties (in millions): Property Annual Interest Rate and (2) Principal Maturity September 30, 2018 (unaudited) December 31, 2017 Mass Court (1) 2.88% paid monthly 90.7 92.1 September 1, 2019 Red Canyon at Palomino Park (4) 5.34% paid monthly 27.1 27.1 August 1, 2020 Green River at Palomino Park (4) 5.34% paid monthly 33.2 33.2 August 1, 2020 Blue Ridge at Palomino Park (4) 5.34% paid monthly 33.4 33.4 August 1, 2020 Ashford Meadows Apartments 5.17% paid monthly 44.6 44.6 August 1, 2020 The Knoll (1) 3.98% paid monthly 17.1 17.5 December 5, 2020 The Corner 4.66% paid monthly 105.0 105.0 June 1, 2021 Ascent at Windward 3.51% paid monthly 34.6 — January 1, 2022 The Palatine (1) 4.25% paid monthly 77.7 78.8 January 10, 2022 The Forum at Carlsbad (1) 4.25% paid monthly 87.7 88.9 March 1, 2022 Fusion 1560 3.42% paid monthly 37.4 — June 10, 2022 The Colorado (1) 3.69% paid monthly 90.3 91.7 November 1, 2022 The Legacy at Westwood (1) 3.69% paid monthly 46.1 46.7 November 1, 2022 Regents Court (1) 3.69% paid monthly 39.1 39.6 November 1, 2022 Fourth & Madison (1) 3.75% paid monthly 199.1 200.0 June 1, 2023 Fourth & Madison 4.17% paid monthly 90.0 — June 1, 2023 1001 Pennsylvania Avenue (1) 3.70% paid monthly 328.5 330.0 June 1, 2023 Biltmore at Midtown 3.94% paid monthly 36.4 — July 5, 2023 Cherry Knoll 3.78% paid monthly 35.3 — July 5, 2023 Lofts at SoDo 3.94% paid monthly 35.1 — July 5, 2023 1401 H Street NW 3.65% paid monthly 115.0 115.0 November 5, 2024 Circa Green Lake 3.71% paid monthly 52.0 — March 5, 2025 Union - South Lake Union 3.66% paid monthly 57.0 — March 5, 2025 Holly Street Village 3.65% paid monthly 81.0 — May 1, 2025 Township Apartments 3.65% paid monthly 49.0 — May 1, 2025 32 South State Street 4.48% paid monthly 24.0 24.0 June 6, 2025 780 Third Avenue 3.55% paid monthly 150.0 150.0 August 1, 2025 780 Third Avenue 3.55% paid monthly 20.0 20.0 August 1, 2025 701 Brickell Avenue 3.66% paid monthly 184.0 184.0 April 1, 2026 55 Second Street (5) 3.74% paid monthly 137.5 137.5 October 1, 2026 1900 K Street, NW 3.93% paid monthly 163.0 163.0 April 1, 2028 501 Boylston Street (6) 3.70% paid monthly — 216.5 April 1, 2028 99 High Street 3.90% paid monthly 277.0 — March 1, 2030 Total Principal Outstanding $ 2,797.9 $ 2,238.6 Fair Value Adjustment (3) (54.7 ) (0.3 ) Total Mortgage Loans Payable $ 2,743.2 $ 2,238.3 (1) The mortgage is adjusted monthly for principal payments. (2) Interest rates are fixed. Some mortgages held by the Account are structured to begin principal and interest payments after an initial interest only period. (3) The fair value adjustment consists of the difference (positive or negative) between the principal amount of the outstanding debt and the fair value of the outstanding debt. See Note 1—Organization and Significant Accounting Policies. (4) Represents mortgage loans on these individual properties which are held within the Palomino Park portfolio. (5) This mortgage is comprised of three individual loans, all with equal recourse, interest rate and maturity. The principal balances by loan are $79.0 million , $45.0 million and $13.5 million . (6) On August 21, 2018 the Account sold a 49.9% interest in the property and transferred the remaining 50.1% to a joint venture investment.

Line of Credit

Line of Credit	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Line of Credit	Line of Credit On September 20, 2018, the Account entered into a $500.0 million unsecured revolving credit agreement (“Line of Credit”) syndicated across four national banks (“Lenders”), with each Lender providing a $125.0 million commitment. Access to the Line of Credit expires on September 20, 2021, with an option to extend the Line of Credit for two consecutive twelve months terms at the Account’s election. The Account may request an additional $250.0 million in commitments from the Lenders at any time; however, this request is subject to approval at the sole discretion of the Lenders and is not a guarantee that an expansion beyond the original $500.0 million commitment will be granted. Draws against the Line of Credit can take the form of Eurodollar Loans or Alternate Base Rate Loans (“ABR Loans”). Eurodollar Loans and ABR Loans both require a minimum funding of $5.0 million . The Account is charged a fee of 0.20% per annum on any unused portion of the Line of Credit. Eurodollar Loans are issued for a term of twelve months or less and bear interest during the period (“Interest Period”) at a rate equal to the Adjusted London Interbank Offer Rate (“Adjusted LIBOR”) plus a spread ranging between 0.85% - 1.05% per annum (the “Applicable Rate”), with the spread dependent upon the leverage ratio of the Account. The Adjusted LIBOR Rate is calculated by multiplying the Statutory Reserve Rate, as determined by the Federal Reserve Board for Eurodollar liabilities, by the LIBOR rate, as determined by the Intercontinental Exchange on the date of issuance that corresponds to the length of the Interest Period of the Eurodollar Loan. The Account may prepay Eurodollar Loans at any time during the life of the loan without penalty. The Account is limited to five active Eurodollar Loans through the Line of Credit; however, the Account may retire and initiate new Eurodollar Loans without restriction so long as the total number of loans in active status never exceeds the limit. ABR Loans are issued for a specific length of time and bear interest at a rate equal to the highest rate among the following calculations plus the Applicable Rate: a) the Prime Rate on the date of issuance, with the Prime Rate being defined as the rate of interest last quoted by the Wall Street Journal as the Prime Rate; b) the Federal Reserve Bank of New York (“NYFRB”) Rate as provided by the NYFRB on the date of issuance plus 0.5% ; or c) the Adjusted LIBOR Rate plus 1.0% . The Account may prepay ABR Loans at any time during the life of the loan without penalty. As of September 30, 2018 , the Account had no active loans outstanding on the Line of Credit. The Account is in compliance with all covenants required by the Line of Credit.

Financial Highlights

Financial Highlights	9 Months Ended
	Sep. 30, 2018
Condensed Financial Information Disclosure [Abstract]
Financial Highlights	Financial Highlights Selected condensed financial information for an Accumulation Unit of the Account is presented below. Per Accumulation Unit data is calculated on average units outstanding. For the Nine Months Ended September 30, 2018 Years Ended December 31, 2017 2016 2015 (Unaudited) Per Accumulation Unit Data: Rental income $ 13.487 $ 17.132 $ 16.433 $ 15.538 Real estate property level expenses and taxes 6.390 7.722 7.534 7.319 Real estate income, net 7.097 9.410 8.899 8.219 Other income 4.461 4.762 3.594 3.342 Total income 11.558 14.172 12.493 11.561 Expense charges (1) 2.402 3.318 3.290 3.092 Investment income, net 9.156 10.854 9.203 8.469 Net realized and unrealized gain on investments and mortgage loans payable 5.994 5.839 9.660 18.911 Net increase in Accumulation Unit Value 15.150 16.693 18.863 27.380 Accumulation Unit Value: Beginning of period 398.329 381.636 362.773 335.393 End of period $ 413.479 $ 398.329 $ 381.636 $ 362.773 Total return (3) 3.80 % 4.37 % 5.20 % 8.16 % Ratios to Average net assets (2) : Expenses (1) 0.78 % 0.83 % 0.86 % 0.86 % Investment income, net 2.97 % 2.72 % 2.41 % 2.37 % Portfolio turnover rate (3) : Real estate properties (4) 7.4 % 2.7 % 1.3 % 5.7 % Marketable securities (5) 3.3 % 5.7 % 3.5 % 10.0 % Accumulation Units outstanding at end of period (in millions) 60.7 61.3 62.4 60.4 Net assets end of period (in millions) $ 25,634.1 $ 24,942.6 $ 24,304.7 $ 22,360.0 (1) Expense charges per Accumulation Unit and the Ratio of Expenses to average net assets reflect the year to date Account level expenses and exclude real estate property level expenses which are included in real estate income, net. (2) Percentages for the nine months ended September 30, 2018 are annualized. (3) Percentages for the nine months ended September 30, 2018 are not annualized. (4) Real estate investment portfolio turnover rate is calculated by dividing the lesser of purchases or sales of real estate property investments (including contributions to, or return of capital distributions received from, existing joint venture and limited partnership investments) by the average value of the portfolio of real estate investments held during the period. (5) Marketable securities portfolio turnover rate is calculated by dividing the lesser of purchases or sales of securities, excluding securities having maturity dates at acquisition of one year or less, by the average value of the portfolio securities held during the period.

Accumulation Units

Accumulation Units	9 Months Ended
	Sep. 30, 2018
Accumulated Units Disclosure [Abstract]
Accumulation Units	Accumulation Units Changes in the number of Accumulation Units outstanding were as follows (in millions): For the Nine Months Ended September 30, 2018 For the Year Ended December 31, 2017 (Unaudited) Outstanding: Beginning of period 61.3 62.4 Credited for premiums 4.7 6.6 Annuity, other periodic payments, withdrawals and death benefits (5.3 ) (7.7 ) End of period 60.7 61.3

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Commitments —As of September 30, 2018 and December 31, 2017, the Account had the following immediately callable commitments to purchase additional interests in its limited partnership investments: September 30, 2018 December 31, 2017 (Unaudited) Taconic New York City GP Fund $ 26.0 $ 32.0 LCS SHIP Venture I, LLC 40.7 — $ 66.7 $ 32.0 Taconic New York City GP Fund—The general partner can call capital during the commitment period at any time. The commitment period is the fifth anniversary from closing (November 2020). The commitment period may be closed earlier at the joint election of TIAA and the general partner if 90% of the commitment has been satisfied. LCS SHIP Venture I, LLC—The general partner can call capital at any time during the commitment period, which is one year from closing (June 2019). Contingencies —In the normal course of business, the Account may be named, from time to time, as a defendant or may be involved in various legal actions, including arbitrations, class actions and other litigation. The Account establishes an accrual for all litigation and regulatory matters when it believes it is probable that a loss has been incurred and the amount of the loss can be reasonably estimated. Once established, accruals are adjusted, as appropriate, in light of additional information. The amount of loss ultimately incurred in relation to those matters may be higher or lower than the amounts accrued for those matters. As of the date of this report, management of the Account does not believe that the results of any such claims or litigation, individually or in the aggregate, will have a material effect on the Account’s business, financial position or results of operations.

Organization and Significant _2

Organization and Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation: The accompanying Consolidated Financial Statements include the Account and those subsidiaries wholly-owned by TIAA for the sole benefit of the Account. All significant intercompany accounts and transactions between the Account and such subsidiaries have been eliminated. The Accumulation Unit Value (“AUV”) used for financial reporting purposes may differ from the AUV used for processing transactions. The AUV used for financial reporting purposes includes security and participant transactions effective through the period end date to which this report relates. Total return is computed based on the AUV used for processing transactions.
Determination of Investments at Fair Value	Determination of Investments at Fair Value: The Account reports all investments at fair value in accordance with the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 946, Financial Services—Investment Companies. Further in accordance with the adoption of the fair value option allowed under ASC 825, Financial Instruments , and at the election of Account management, mortgage loans payable and a line of credit are reported at fair value. The FASB has defined 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 excluding transaction costs. The following is a description of the valuation methodologies used to determine the fair value of the Account’s investments and investment related mortgage loans payable. Valuation of Real Estate Properties —Investments in real estate properties are stated at fair value, as determined in accordance with policies and procedures reviewed by the Investment Committee of the Board and in accordance with the responsibilities of the Board as a whole. Accordingly, the Account does not record depreciation. Determination of fair value involves significant levels of judgment because the actual fair value of real estate can be determined only by negotiation between the parties in a sales transaction. The Account’s primary objective when valuing its real estate investments is to produce a valuation that represents a reasonable estimate of the fair value of its investments. Implicit in the Account’s definition of fair value are the consummation of a sale as of a specified date and the passing of title from seller to buyer under conditions whereby: • Buyer and seller are typically motivated; • Both parties are well informed or well advised, and acting in what they consider their best interests; • A reasonable time is allowed for exposure in the open market; • Payment is made in terms of cash or in terms of financial arrangements comparable thereto; and • The price represents the normal consideration for the property sold unaffected by special or creative financing or sales concessions granted by anyone associated with the sale. Property and investment values are affected by, among other things, the availability of capital, occupancy rates, rental rates, and interest and inflation rates. As a result, determining real estate and investment values involves many assumptions. Key inputs and assumptions include rental income and expense amounts, related rental income and expense growth rates, capital expenditures, discount rates and capitalization rates. Valuation techniques include discounted cash flow analysis, prevailing market capitalization rates or multiples applied to earnings from the property, analysis of recent comparable sales transactions, actual sale negotiations and bona fide purchase offers received from third parties. Amounts ultimately realized from each investment may vary significantly from the fair value presented. Real estate properties owned by the Account are initially valued based on an independent third party appraisal, as reviewed by TIAA’s internal appraisal staff and as applicable by the Account’s independent fiduciary at the time of the closing of the purchase. Such initial valuation may result in a potential unrealized gain or loss reflecting the difference between an investment’s fair value (i.e., exit price) and its cost basis (which is inclusive of transaction costs). Subsequently, each property is appraised each quarter by an independent third party appraiser, reviewed by TIAA’s internal appraisal staff and as applicable the Account’s independent fiduciary. In general, the Account obtains appraisals of its real estate properties spread out throughout the quarter, which is intended to result in appraisal adjustments, and thus, adjustments to the valuations of its holdings (to the extent such adjustments are made) that happen regularly throughout each quarter and not on one specific day or month in each period. Further, management reserves the right to order an appraisal and/or conduct another valuation outside of the normal quarterly process when facts or circumstances at a specific property change. For example, under certain circumstances a valuation adjustment could be made when the account receives a bona fide bid for the sale of a property held within the Account or one of the Account’s joint ventures. Adjustments may be made for events or circumstances indicating an impairment of a tenant’s ability to pay amounts due to the Account under a lease (including due to a bankruptcy filing of that tenant). Alternatively, adjustments may be made to reflect the execution or renewal of a significant lease. Also, adjustments may be made to reflect factors (such as sales values for comparable properties or local employment rate) bearing uniquely on a particular region in which the Account holds properties. TIAA’s internal appraisal staff oversees the entire appraisal process, in conjunction with the Account’s independent fiduciary (the independent fiduciary is more fully described in the following paragraph). Any differences in the conclusions of TIAA’s internal appraisal staff and the independent appraiser will be reviewed by the independent fiduciary, which will make a final determination on the matter (which may include ordering a subsequent independent appraisal). The independent fiduciary, RERC, LLC, was initially appointed in March 2006 by a special subcommittee of the Investment Committee of the Board to, among other things, oversee the entire appraisal process. In March 2018, RERC, LLC, was re-appointed as the Account's independent fiduciary for a term expiring in February 2021. The independent fiduciary must approve all independent appraisers used by the Account. All appraisals are performed in accordance with Uniform Standards of Professional Appraisal Practices, the real estate appraisal industry standards created by The Appraisal Foundation. Real estate appraisals are estimates of property values based on a professional’s opinion. Appraisals of properties held outside of the U.S. are performed in accordance with industry standards commonly applied in the applicable jurisdiction. These independent appraisers are always expected to be MAI-designated members of the Appraisal Institute (or its European equivalent, Royal Institute of Chartered Surveyors) and state certified appraisers from national or regional firms with relevant property type experience and market knowledge. Under the Account’s current procedures, each independent appraisal firm will be rotated off of a particular property at least every three years, although such appraisal firm may perform appraisals of other Account properties subsequent to such rotation. Also, the independent fiduciary may require additional appraisals if factors or events have occurred that could materially change a property’s value (including those identified previously) and such change is not reflected in the quarterly valuation review, or otherwise to ensure that the Account is valued appropriately. The independent fiduciary must also approve any valuation change of real estate-related assets where a property’s value changed by more than 6% from the most recent independent annual appraisal, or if the value of the Account would change by more than 4% within any calendar quarter or more than 2% since the prior calendar month. When a real estate property is subject to a mortgage, the property is valued independently of the mortgage and the property and mortgage fair values are reported separately (see Valuation of Mortgage Loans Payable ). The independent fiduciary reviews and approves all mortgage valuation adjustments before such adjustments are recorded by the Account. The Account continues to use the revised value for each real estate property and mortgage loan payable to calculate the Account’s daily net asset value until the next valuation review or appraisal. Valuation of Real Estate Joint Ventures —Real estate joint ventures are stated at the fair value of the Account’s ownership interests of the underlying entities. The Account’s ownership interests are valued based on the fair value of the underlying real estate, any related mortgage loans payable, and other factors, such as ownership percentage, ownership rights, buy/sell agreements, distribution provisions and capital call obligations. Upon the disposition of all real estate investments by an investee entity, the Account will continue to state its equity in the remaining net assets of the investee entity during the wind down period, if any, which occurs prior to the dissolution of the investee entity. Valuation of Real Estate Limited Partnerships —Limited partnership interests are stated at the fair value of the Account’s ownership in the partnership, with fair value defined as the net asset value. The Account receives net asset values from limited partners on a quarterly basis. Upon receipt, TIAA's internal appraisal staff review such information and conclude on whether the net asset values provided are an appropriate representation of the fair value of the Account's interests in the limited partnerships. Since market quotations or values from independent pricing services are not readily available or are not considered reliable, the limited partnership interests are valued at fair value as determined in good faith by management under the direction of the Investment Committee of the Board and in accordance with the responsibilities of the Board as a whole. Valuation of Marketable Securities —Equity securities listed or traded on any national market or exchange are valued at the last sale price as of the close of the principal securities market or exchange on which such securities are traded or, if there is no sale, at the mean of the last bid and asked prices on such market or exchange, exclusive of transaction costs. Valuation of Debt Securities —Debt securities with readily available market quotations, other than money market instruments, are generally valued at the most recent bid price or the equivalent quoted yield for such securities (or those of comparable maturity, quality and type). Debt securities for which market quotations or values from independent pricing services are not readily available or are not considered reliable, are valued at fair value as determined in good faith by management under the direction of the Investment Committee of the Board and in accordance with the responsibilities of the Board as a whole. Short-term investments are valued in the same manner as debt securities, as described above. Money market instruments are valued at amortized cost, which approximates fair value. Valuation of Loans Receivable (i.e., the Account as a creditor) —Loans receivable are stated at fair value and are initially valued at the face amount of the loan funding. Subsequently, loans receivable are valued at least quarterly by TIAA’s internal valuation department based on market factors, such as market interest rates and spreads for comparable loans, the liquidity for loans of similar characteristics, the performance of the underlying collateral (such as the loan-to-value ratio and the cash flow of the underlying collateral) and the credit quality of the counterparty. The independent fiduciary reviews and approves all loan receivable valuation adjustments before such adjustments are recorded by the Account. Valuation of Mortgage Loans Payable and Line of Credit (i.e., the Account as a debtor) —Mortgage loans payable and the Account's unsecured revolving line of credit (collectively "Debt") are stated at fair value. The estimated fair values of Debt are based on the amount at which Debt could be transferred to a third party exclusive of transaction costs. Debt is valued internally by TIAA’s internal valuation department, as reviewed by the Account’s independent fiduciary, at least quarterly based on market factors, such as market interest rates and spreads for comparable loans, the performance of the underlying collateral (such as the loan-to-value ratio and the cash flow of the underlying collateral), the liquidity for mortgage loans of similar characteristics, the maturity date of the loan, the credit quality of the Account and the return demands of the market.
Accumulation and Annuity Funds	Accumulation and Annuity Funds: The accumulation fund represents the net assets attributable to participants in the accumulation phase of their investment (“Accumulation Fund”). The annuity fund represents the net assets attributable to the participants currently receiving annuity payments (“Annuity Fund”). The net increase or decrease in net assets from investment operations is apportioned between the funds based upon their relative daily net asset values. Once an Account participant begins receiving lifetime annuity income benefits, payment levels cannot be reduced as a result of the Account’s actual mortality experience. In addition, the contracts pursuant to which the Account is offered are required to stipulate the maximum expense charge for all Account level expenses that can be assessed, which is not to exceed 2.5% of average net assets per year. The Account pays a fee to TIAA to assume mortality and expense risks.
Accounting for Investments	Accounting for Investments: The investments held by the Account are accounted for as follows: Real Estate Properties —Rent from real estate properties consists of all amounts earned under tenant leases, including base rent, recoveries of real estate taxes and other expenses and charges for miscellaneous services provided to tenants. Rental income is recognized in accordance with the billing terms of the lease agreements. The Account bears the direct expenses of the real estate properties owned. These expenses include, but are not limited to, fees to local property management companies, property taxes, utilities, maintenance, repairs, insurance, and other operating and administrative costs. An estimate of the net operating income earned from each real estate property is accrued by the Account on a daily basis and such estimates are adjusted when actual operating results are determined. Real Estate Joint Ventures —The Account has ownership interests in various real estate joint ventures (collectively, the “joint ventures”). The Account records its contributions as increases to its investments in the joint ventures, and distributions from the joint ventures are treated as income within income from real estate joint ventures and limited partnerships in the Account’s Consolidated Statements of Operations. Distributions that are identified as returns of capital are recorded as a reduction to the cost basis of the investment, whereas distributions identified as capital gains or losses are recorded as realized gains or losses. Income distributions from the joint ventures are recorded based on the Account’s proportional interest of the income distributed by the joint ventures. Income and losses incurred but not yet distributed or realized from the Account by the joint ventures are recorded as unrealized gains and losses. Limited Partnerships —The Account has ownership interests in various private real estate funds (primarily limited partnerships) and a private real estate investment trust (collectively, the “limited partnerships”). The Account records its contributions as increases to the investments, and distributions from the investments are treated as income within income from real estate joint ventures and limited partnerships in the Account’s Consolidated Statements of Operations. Distributions that are identified as returns of capital are recorded as a reduction to the cost basis of the investment, whereas distributions identified as capital gains or losses are recorded as realized gains or losses. Unrealized gains and losses are recorded based upon the changes in the net asset values of the limited partnerships as determined from the financial statements of the limited partnerships when received by the Account. Prior to the receipt of the financial statements from the limited partnerships, the Account estimates the value of its interest in good faith and will from time to time seek input from the issuer or the sponsor of the investments. Changes in value based on such estimates are recorded by the Account as unrealized gains and losses. Marketable Securities —Transactions in marketable securities are accounted for as of the date the securities are purchased or sold (trade date). Interest income is recorded as earned. Dividend income is recorded on the ex-dividend date within dividend income. Dividends that are identified as returns of capital are recorded as a reduction to the cost basis of the investment, whereas dividends identified as capital gains or losses are recorded as realized gains or losses. Realized gains and losses on securities transactions are accounted for on the specific identification method. Loans Receivable —The Account has ownership interests in loans receivable. Loans receivable are stated at fair value and are initially valued at the face amount of the loan funding. Subsequently, loans receivable are valued at least quarterly by TIAA’s internal valuation department with changes in fair value flowing through unrealized gain (loss). Interest income from loans receivable is recognized in accordance with the terms of the loans. Realized and Unrealized Gains and Losses —Realized gains and losses are recorded at the time an investment is sold or a distribution is received in relation to an investment sale from a joint venture or limited partnership. Real estate transactions are accounted for as of the date on which the purchase or sale transactions for the real estate properties close (settlement date). The Account recognizes a realized gain on the sale of a real estate property to the extent that the contract sales price exceeds the cost-to-date of the property being sold. A realized loss occurs when the cost-to-date exceeds the sales price. Realized gains and losses from partial sales of non-financial assets are recognized in accordance with ASC 610-20 - Gains and Losses from the Derecognition of Nonfinancial Assets . Unrealized gains and losses are recorded as the fair values of the Account’s investments are adjusted, and as discussed within the Real Estate Joint Ventures and Limited Partnerships sections above. Net Assets —The Account’s net assets as of the close of each valuation day are valued by taking the sum of: • the value of the Account’s cash, cash equivalents, and short-term and other debt instruments; • the value of the Account’s other securities and other non-real estate assets; • the value of the individual real properties (based on the most recent valuation of that property) and other real estate-related investments owned by the Account; • an estimate of the net operating income accrued by the Account from its properties, other real estate-related investments and non-real estate-related investments (including short-term marketable securities) since the end of the prior valuation day; and • actual net operating income earned from the Account’s properties, other real estate-related investments and non-real estate-related investments (but only to the extent any such item of income differs from the estimated income accrued for on such investments), and then reducing the sum by liabilities held within the Account, including the daily investment management fee, administration and distribution fees, mortality and expense fees, and the liquidity guarantee fee, and certain other expenses attributable to operating the Account. Daily estimates of net operating income are adjusted to reflect actual net operating income on a monthly basis, at which time such adjustments (if any) are reflected in the Account’s unit value. After the end of every quarter, the Account reconciles the amount of expenses deducted from the Account (which is established in order to approximate the costs that the Account will incur) with the expenses the Account actually incurred. If there is a difference, the Account adds it to or deducts it from the Account in equal daily installments over the remaining days of the following quarter. Material differences may be repaid in the current calendar quarter. The Account’s at cost deductions are based on projections of Account assets and overall expenses, and the size of any adjusting payments will be directly affected by the difference between management’s projections and the Account’s actual assets or expenses.
Cash and Cash Equivalents	Cash and Cash Equivalents: Cash and cash equivalents are balances held by the Account in bank deposit accounts which, at times, exceed federally insured limits. The Account’s management monitors these balances to mitigate the exposure of risk due to concentration and has not experienced any losses from such concentration.
Other Assets and Other Liabilities	Other Assets and Other Liabilities: Other assets and other liabilities consist of operating assets and liabilities incurred and held at each individual real estate property investment. Other assets consist of, among other items, cash, tenant receivables and prepaid expenses; whereas other liabilities primarily consist of accrued real estate taxes and security deposits. Other assets also include cash collateral held for securities on loan.
Federal Income Taxes	Federal Income Taxes: Based on provisions of the Internal Revenue Code, Section 817, the Account is taxed as a segregated asset account of TIAA and as such, the Account incurs no material federal income tax attributable to the net investment activity of the Account. The Account’s federal income tax return is generally subject to examination for a period of three years after it is filed. State and local tax returns may be subject to examination for an additional period of time depending on the jurisdiction. Management has analyzed the Account’s tax positions taken for all open federal income tax years and has concluded that no provision for federal income tax is required in the Account’s Consolidated Financial Statements.
Restricted Cash	Restricted Cash: The Account held restricted cash in escrow accounts for security deposits, as required by certain states, as well as property taxes, insurance, and various other property related matters as required by certain creditors related to outstanding mortgage loans payable collateralized by certain real estate investments. These amounts are recorded within other assets on the Consolidated Statements of Assets and Liabilities.
Changes In Net Assets	Changes in Net Assets: Premiums include premiums paid by existing accumulation unit holders in the Account and transfers into the Account. Withdrawals and death benefits include withdrawals out of the Account which include transfers out of the Account and required minimum distributions.
Due to/from Investment Manager	Due to/from Investment Manager: Due to/from investment manager represents amounts that are to be paid or received by TIAA on behalf of the Account. Amounts generally are paid or received by the Account within one or two business days and no interest is contractually charged on these amounts.
Securities Lending	Securities Lending: The Account may lend securities to qualified borrowers to earn additional income. The Account receives cash collateral against the loaned securities and maintains cash collateral in an amount not less than 100% of the market value of loaned securities during the period of the loan; any additional collateral required due to changes in security values is delivered to the Account the next business day. Cash collateral received by the Account is invested exclusively in an interest-bearing deposit account. The value of the loaned securities and the liability to return the cash collateral received are reflected in the Consolidated Statements of Assets and Liabilities. When loaning securities, the Account retains the benefits of owning the securities, including the economic equivalent of dividends or interest generated by the securities. All income generated by the securities lending program is reflected within interest income on the Consolidated Statements of Operations. As of September 30, 2018 , securities lending transactions are for real-estate related equity securities, and the resulting loans are continuous, can be recalled at any time, and have no set maturity. Securities lending income recognized by the Account consists of interest earned on cash collateral and lending fees, net of any rebates to the borrower and compensation to the agent. Such income is reflected within interest income on the Consolidated Statements of Operations. In lending its securities, the Account bears the market risk with respect to the investment of collateral and the risk that the agent may default on its contractual obligations to the Account. The agent bears the risk that the borrower may default on its obligation to return the loaned securities as the agent is contractually obligated to indemnify the Account if at the time of a default by a borrower some or all of the loan securities have not been returned.
New Accounting Pronouncements	New Accounting Pronouncements In May 2014, the FASB issued Accounting Standard Update 2014-09, Revenue from Contracts with Customers (“ASU 2014-09”). ASU 2014-09 supersedes all existing revenue recognition guidance and establishes a five-step model to measure and recognize revenue. ASU 2014-09 was effective for fiscal years beginning after December 15, 2017 and the Account adopted this guidance as of January 1, 2018 utilizing the modified retrospective adoption approach. Under this approach, ASU 2014-09 was applied to all contracts that were not completed as of the date of adoption. Based on the Accounts implementation procedures, the adoption of ASU 2014-09 had an immaterial impact to the Account. In February 2016, the FASB issued Accounting Standards Update 2016-02 Leases (Topic 842) (“ASU 2016-02”) which will supersede Topic 840, Leases. This ASU applies to all entities that enter into a lease. Lessees will be required to report assets and liabilities that arise from leases. Lessor accounting is expected to remain unchanged; however, certain refinements were made to conform with the recently issued revenue recognition guidance in ASU 2014-09, specifically related to the allocation and recognition of contract consideration earned from lease and non-lease revenue components. The ASU contains certain practical expedients, which the Account plans to elect. The Account is electing the transition package of practical expedients permitted within the new standard. This practical expedient permits the Account to carryforward the historical lease classification and not to reassess initial direct costs for any existing leases. Further, the Account will initially apply the new lease requirements at the effective date of January 1, 2019, and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. In addition, the Account plans to elect the practical expedient that allows lessors to avoid separating lease and non-lease components within a contract if certain criteria are met. The lessor’s practical expedient election would be limited to circumstances in which (i) the timing and pattern of revenue recognition are the same for the non-lease component and the related lease component and (ii) the combined single lease component would be classified as an operating lease. This practical expedient would allow the Account the ability to combine the lease and non-lease components if the underlying asset meets the two criteria above. This ASU is effective for public business entities for fiscal years beginning after December 15, 2018, including all interim periods within those fiscal years. Management has completed its initial scoping for the adoption of the ASU 2016-02 and does not expect the adoption of such guidance to materially impact the Account. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement: Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurements. ASU 2018-13 modifies the disclosures required for fair value measurements. This guidance is effective for fiscal years beginning after December 15, 2019. Management is currently evaluating the impact of this guidance but does not expect it to materially impact the Account's Notes to the Consolidated Financial Statements.

Concentrations of Risk (Tables)

Concentrations of Risk (Tables)	9 Months Ended
	Sep. 30, 2018
Risks and Uncertainties [Abstract]
Schedules of Concentration of Risk, by Risk Factor	The following table represents the diversification of the Account’s portfolio by region and property type as of September 30, 2018 (unaudited): Diversification by Fair Value (1) West East South Midwest Total Office 14.0 % 18.6 % 5.5 % — % 38.1 % Apartment 8.7 % 8.3 % 6.0 % 1.1 % 24.1 % Retail 8.1 % 3.1 % 7.8 % 0.7 % 19.7 % Industrial 8.1 % 1.7 % 4.4 % 0.5 % 14.7 % Other (2) 0.6 % 2.6 % 0.1 % 0.1 % 3.4 % Total 39.5 % 34.3 % 23.8 % 2.4 % 100.0 % (1) Wholly-owned properties are represented at fair value and gross of any debt, while joint venture properties are represented at the net equity value. (2) Represents interests in Storage Portfolio investments, a fee interest encumbered by a ground lease real estate investment and land. Properties in the “West” region are located in: AK, AZ, CA, CO, HI, ID, MT, NM, NV, OR, UT, WA, WY Properties in the “East” region are located in: CT, DC, DE, KY, MA, MD, ME, NC, NH, NJ, NY, PA, RI, SC, VA, VT, WV Properties in the “South” region are located in: AL, AR, FL, GA, LA, MS, OK, TN, TX Properties in the “Midwest” region are located in: IA, IL, IN, KS, MI, MN, MO, ND, NE, OH, SD, WI

Assets and Liabilities Measur_2

Assets and Liabilities Measured at Fair Value on a Recurring Basis (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following tables show the major categories of assets and liabilities measured at fair value on a recurring basis as of September 30, 2018 (unaudited) and December 31, 2017 , using unadjusted quoted prices in active markets for identical assets (Level 1); significant other observable inputs (Level 2); and significant unobservable inputs (Level 3); and fair value using the practical expedient (in millions): Description Level 1: Quoted Prices in Active Markets for Identical Assets Level 2: Significant Other Observable Inputs Level 3: Significant Unobservable Inputs Fair Value Using Practical Expedient Total at Real estate properties $ — $ — $ 15,345.9 $ — $ 15,345.9 Real estate joint ventures — — 5,795.3 — 5,795.3 Limited partnerships — — — 140.9 140.9 Marketable securities: Real estate-related 1,430.6 — — — 1,430.6 Government agency notes — 2,560.7 — — 2,560.7 United States Treasury securities — 2,284.0 — — 2,284.0 Loans receivable — — 855.1 — 855.1 Total Investments at $ 1,430.6 $ 4,844.7 $ 21,996.3 $ 140.9 $ 28,412.5 Mortgage loans payable $ — $ — $ (2,743.2 ) $ — $ (2,743.2 ) Description Level 1: Quoted Prices in Active Markets for Identical Assets Level 2: Significant Other Observable Inputs Level 3: Significant Unobservable Inputs Fair Value Using Practical Expedient Total at December 31, 2017 Real estate properties $ — $ — $ 15,742.7 $ — $ 15,742.7 Real estate joint ventures — — 5,860.6 — 5,860.6 Limited partnerships — — — 142.4 142.4 Marketable securities: Real estate-related 1,238.0 — — — 1,238.0 Government agency notes — 2,872.3 — — 2,872.3 United States Treasury securities — 1,015.2 — — 1,015.2 Loans receivable — — 298.8 — 298.8 Total Investments at December 31, 2017 $ 1,238.0 $ 3,887.5 $ 21,902.1 $ 142.4 $ 27,170.0 Mortgage loans payable $ — $ — $ (2,238.3 ) $ — $ (2,238.3 )
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation	The following tables show the reconciliation of the beginning and ending balances for assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) during the three and nine months ended September 30, 2018 and 2017 (in millions, unaudited): Real Estate Real Estate Loans Total Mortgage For the three months ended September 30, 2018 Beginning balance July 1, 2018 $ 16,042.7 $ 5,915.3 $ 618.3 $ 22,576.3 $ (2,891.4 ) Total realized and unrealized gains (losses) included in changes in net assets 114.6 7.5 1.0 123.1 (0.8 ) Purchases (1) 253.7 242.1 380.1 875.9 (72.0 ) Sales (1,065.1 ) — — (1,065.1 ) — Settlements (2) — (369.6 ) (144.3 ) (513.9 ) 221.0 Ending balance September 30, 2018 $ 15,345.9 $ 5,795.3 $ 855.1 $ 21,996.3 $ (2,743.2 ) Real Estate Real Estate Loans Total Mortgage For the nine months ended September 30, 2018 Beginning balance January 1, 2018 $ 15,742.7 $ 5,860.6 $ 298.8 $ 21,902.1 $ (2,238.3 ) Total realized and unrealized gains included in changes in net assets 212.9 99.1 1.0 313.0 54.4 Purchases (1) 830.3 325.9 699.6 1,855.8 (817.9 ) Sales (1,440.0 ) — — (1,440.0 ) — Settlements (2) — (490.3 ) (144.3 ) (634.6 ) 258.6 Ending balance September 30, 2018 $ 15,345.9 $ 5,795.3 $ 855.1 $ 21,996.3 $ (2,743.2 ) Real Estate Real Estate Loans Total Mortgage For the three months ended September 30, 2017 Beginning balance July 1, 2017 $ 15,496.6 $ 5,946.8 $ 297.3 $ 21,740.7 $ (2,290.1 ) Total realized and unrealized gains (losses) included in changes in net assets 65.8 17.6 1.4 84.8 (4.1 ) Purchases (1) 317.1 13.1 0.1 330.3 (17.7 ) Sales (225.3 ) — — (225.3 ) — Settlements (2) — (302.1 ) — (302.1 ) 0.9 Ending balance September 30, 2017 $ 15,654.2 $ 5,675.4 $ 298.8 $ 21,628.4 $ (2,311.0 ) Real Estate Real Estate Loans Total Mortgage For the nine months ended September 30, 2017 Beginning balance January 1, 2017 $ 15,452.8 $ 5,622.4 $ 295.7 $ 21,370.9 $ (2,332.1 ) Total realized and unrealized gains (losses) included in changes in net assets 133.2 80.4 1.4 215.0 (10.6 ) Purchases (1) 408.9 275.6 1.7 686.2 (17.7 ) Sales (340.7 ) — — (340.7 ) — Settlements (2) — (303.0 ) — (303.0 ) 49.4 Ending balance September 30, 2017 $ 15,654.2 $ 5,675.4 $ 298.8 $ 21,628.4 $ (2,311.0 ) (1) Includes purchases, contributions for joint ventures, capital expenditures, lending for loans receivable and assumption of mortgage loans payable. (2) Includes operating income for real estate joint ventures, net of distributions, principal payments and extinguishment of mortgage loans payable.
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation	The following tables show the reconciliation of the beginning and ending balances for assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) during the three and nine months ended September 30, 2018 and 2017 (in millions, unaudited): Real Estate Real Estate Loans Total Mortgage For the three months ended September 30, 2018 Beginning balance July 1, 2018 $ 16,042.7 $ 5,915.3 $ 618.3 $ 22,576.3 $ (2,891.4 ) Total realized and unrealized gains (losses) included in changes in net assets 114.6 7.5 1.0 123.1 (0.8 ) Purchases (1) 253.7 242.1 380.1 875.9 (72.0 ) Sales (1,065.1 ) — — (1,065.1 ) — Settlements (2) — (369.6 ) (144.3 ) (513.9 ) 221.0 Ending balance September 30, 2018 $ 15,345.9 $ 5,795.3 $ 855.1 $ 21,996.3 $ (2,743.2 ) Real Estate Real Estate Loans Total Mortgage For the nine months ended September 30, 2018 Beginning balance January 1, 2018 $ 15,742.7 $ 5,860.6 $ 298.8 $ 21,902.1 $ (2,238.3 ) Total realized and unrealized gains included in changes in net assets 212.9 99.1 1.0 313.0 54.4 Purchases (1) 830.3 325.9 699.6 1,855.8 (817.9 ) Sales (1,440.0 ) — — (1,440.0 ) — Settlements (2) — (490.3 ) (144.3 ) (634.6 ) 258.6 Ending balance September 30, 2018 $ 15,345.9 $ 5,795.3 $ 855.1 $ 21,996.3 $ (2,743.2 ) Real Estate Real Estate Loans Total Mortgage For the three months ended September 30, 2017 Beginning balance July 1, 2017 $ 15,496.6 $ 5,946.8 $ 297.3 $ 21,740.7 $ (2,290.1 ) Total realized and unrealized gains (losses) included in changes in net assets 65.8 17.6 1.4 84.8 (4.1 ) Purchases (1) 317.1 13.1 0.1 330.3 (17.7 ) Sales (225.3 ) — — (225.3 ) — Settlements (2) — (302.1 ) — (302.1 ) 0.9 Ending balance September 30, 2017 $ 15,654.2 $ 5,675.4 $ 298.8 $ 21,628.4 $ (2,311.0 ) Real Estate Real Estate Loans Total Mortgage For the nine months ended September 30, 2017 Beginning balance January 1, 2017 $ 15,452.8 $ 5,622.4 $ 295.7 $ 21,370.9 $ (2,332.1 ) Total realized and unrealized gains (losses) included in changes in net assets 133.2 80.4 1.4 215.0 (10.6 ) Purchases (1) 408.9 275.6 1.7 686.2 (17.7 ) Sales (340.7 ) — — (340.7 ) — Settlements (2) — (303.0 ) — (303.0 ) 49.4 Ending balance September 30, 2017 $ 15,654.2 $ 5,675.4 $ 298.8 $ 21,628.4 $ (2,311.0 ) (1) Includes purchases, contributions for joint ventures, capital expenditures, lending for loans receivable and assumption of mortgage loans payable. (2) Includes operating income for real estate joint ventures, net of distributions, principal payments and extinguishment of mortgage loans payable.
Schedule of Unobservable Inputs Related to Level 3 Fair Value Measurements	The following table shows quantitative information about unobservable inputs related to the Level 3 fair value measurements as of September 30, 2018 (unaudited). Type Asset Class Valuation Unobservable Range (Weighted Average) Real Estate Properties and Joint Ventures Office Income Approach—Discounted Cash Flow Discount Rate 5.5% - 8.6% (6.5%) Income Approach—Direct Capitalization Overall Capitalization Rate 4.0% - 7.0% (4.9%) Industrial Income Approach—Discounted Cash Flow Discount Rate 5.5% - 8.9% (6.8%) Income Approach—Direct Capitalization Overall Capitalization Rate 4.0% - 7.5% (5.0%) Apartment Income Approach—Discounted Cash Flow Discount Rate 5.3% - 7.8% (6.3%) Income Approach—Direct Capitalization Overall Capitalization Rate 3.3% - 5.8% (4.5%) Retail Income Approach—Discounted Cash Flow Discount Rate 5.0% - 10.5% (6.4%) Income Approach—Direct Capitalization Overall Capitalization Rate 3.8% - 10.5% (4.6%) Mortgage Loans Payable Office and Industrial Discounted Cash Flow Loan to Value Ratio 37.7% - 70.7% (43.2%) Net Present Value Loan to Value Ratio 37.7% - 70.7% (43.2%) Apartment Discounted Cash Flow Loan to Value Ratio 32.3% - 63.9% (47.2%) Net Present Value Loan to Value Ratio 32.3% - 63.9% (47.2%) Retail Discounted Cash Flow Loan to Value Ratio 17.6% - 55.3% (33.2%) Net Present Value Loan to Value Ratio 17.6% - 55.3% (33.2%) Loans Receivable Office, Retail and Storage Discounted Cash Flow Loan to Value Ratio 70.8% - 79.2% (75.8%) The following table shows quantitative information about unobservable inputs related to the Level 3 fair value measurements as of September 30, 2017 (unaudited). Type Asset Class Valuation Unobservable Range (Weighted Average) Real Estate Properties and Joint Ventures Office Income Approach—Discounted Cash Flow Discount Rate 5.5% - 8.0% (6.5%) Income Approach—Direct Capitalization Overall Capitalization Rate 3.8% - 7.0% (4.8%) Industrial Income Approach—Discounted Cash Flow Discount Rate 5.5% - 8.5% (6.6%) Income Approach—Direct Capitalization Overall Capitalization Rate 4.0% - 7.5% (4.9%) Apartment Income Approach—Discounted Cash Flow Discount Rate 5.0% - 8.0% (6.1%) Income Approach—Direct Capitalization Overall Capitalization Rate 3.3% - 6.0% (4.3%) Retail Income Approach—Discounted Cash Flow Discount Rate 5.0% - 10.4% (6.4%) Income Approach—Direct Capitalization Overall Capitalization Rate 3.9% - 8.8% (4.6%) Mortgage Loans Payable Office and Industrial Discounted Cash Flow Loan to Value Ratio 38.0% - 70.0% (44.0%) Net Present Value Loan to Value Ratio 38.0% - 70.0% (44.0%) Apartment Discounted Cash Flow Loan to Value Ratio 28.1% - 65.6% (41.2%) Net Present Value Loan to Value Ratio 28.1% - 65.6% (41.2%) Retail Discounted Cash Flow Loan to Value Ratio 18.0% - 56.2% (32.9%) Net Present Value Loan to Value Ratio 18.0% - 56.2% (32.9%) Loans Receivable Office, Retail and Storage Discounted Cash Flow Loan to Value Ratio 60.1% - 74.5% (73.9%)
Fair Value Of Net Unrealized Gains Included In Changes In Net Assets Attributable To Investments And Mortgage Loans Payable Using Significant Unobservable Inputs	The amount of total net unrealized gains (losses) included in changes in net assets attributable to the change in net unrealized gains (losses) relating to Level 3 investments and mortgage loans payable using significant unobservable inputs still held as of the reporting date is as follows (in millions, unaudited): Real Estate Properties Real Estate Joint Ventures Loans Receivable Total Level 3 Investments Mortgage Loans Payable For the three months ended September 30, 2018 $ 48.1 $ (18.1 ) $ 1.1 $ 31.1 $ 4.8 For the nine months ended September 30, 2018 $ 158.8 $ 73.5 $ 1.1 $ 233.4 $ 60.0 For the three months ended September 30, 2017 $ 68.0 $ 17.9 $ 1.4 $ 87.3 $ (4.1 ) For the nine months ended September 30, 2017 $ 139.0 $ 80.7 $ 1.4 $ 221.1 $ (10.6 )

Investments in Joint Ventures (

Investments in Joint Ventures (Tables)	9 Months Ended
	Sep. 30, 2018
Equity Method Investments and Joint Ventures [Abstract]
Schedule of Results of Operations of the Joint Ventures	A condensed summary of the results of operations of the joint ventures are shown below (in millions, unaudited): For the Three Months Ended September 30, For the Nine Months Ended September 30, 2018 2017 2018 2017 Operating Revenue and Expenses Revenues $ 237.2 $ 218.0 $ 694.2 $ 645.0 Expenses 122.8 108.3 381.0 315.0 Excess of revenues over expenses $ 114.4 $ 109.7 $ 313.2 $ 330.0

Mortgage Loans Payable (Tables)

Mortgage Loans Payable (Tables)	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Schedule Of Outstanding Mortgage Loans Payable Secured By Properties	At September 30, 2018 , the Account had outstanding mortgage loans payable secured by the following properties (in millions): Property Annual Interest Rate and (2) Principal Maturity September 30, 2018 (unaudited) December 31, 2017 Mass Court (1) 2.88% paid monthly 90.7 92.1 September 1, 2019 Red Canyon at Palomino Park (4) 5.34% paid monthly 27.1 27.1 August 1, 2020 Green River at Palomino Park (4) 5.34% paid monthly 33.2 33.2 August 1, 2020 Blue Ridge at Palomino Park (4) 5.34% paid monthly 33.4 33.4 August 1, 2020 Ashford Meadows Apartments 5.17% paid monthly 44.6 44.6 August 1, 2020 The Knoll (1) 3.98% paid monthly 17.1 17.5 December 5, 2020 The Corner 4.66% paid monthly 105.0 105.0 June 1, 2021 Ascent at Windward 3.51% paid monthly 34.6 — January 1, 2022 The Palatine (1) 4.25% paid monthly 77.7 78.8 January 10, 2022 The Forum at Carlsbad (1) 4.25% paid monthly 87.7 88.9 March 1, 2022 Fusion 1560 3.42% paid monthly 37.4 — June 10, 2022 The Colorado (1) 3.69% paid monthly 90.3 91.7 November 1, 2022 The Legacy at Westwood (1) 3.69% paid monthly 46.1 46.7 November 1, 2022 Regents Court (1) 3.69% paid monthly 39.1 39.6 November 1, 2022 Fourth & Madison (1) 3.75% paid monthly 199.1 200.0 June 1, 2023 Fourth & Madison 4.17% paid monthly 90.0 — June 1, 2023 1001 Pennsylvania Avenue (1) 3.70% paid monthly 328.5 330.0 June 1, 2023 Biltmore at Midtown 3.94% paid monthly 36.4 — July 5, 2023 Cherry Knoll 3.78% paid monthly 35.3 — July 5, 2023 Lofts at SoDo 3.94% paid monthly 35.1 — July 5, 2023 1401 H Street NW 3.65% paid monthly 115.0 115.0 November 5, 2024 Circa Green Lake 3.71% paid monthly 52.0 — March 5, 2025 Union - South Lake Union 3.66% paid monthly 57.0 — March 5, 2025 Holly Street Village 3.65% paid monthly 81.0 — May 1, 2025 Township Apartments 3.65% paid monthly 49.0 — May 1, 2025 32 South State Street 4.48% paid monthly 24.0 24.0 June 6, 2025 780 Third Avenue 3.55% paid monthly 150.0 150.0 August 1, 2025 780 Third Avenue 3.55% paid monthly 20.0 20.0 August 1, 2025 701 Brickell Avenue 3.66% paid monthly 184.0 184.0 April 1, 2026 55 Second Street (5) 3.74% paid monthly 137.5 137.5 October 1, 2026 1900 K Street, NW 3.93% paid monthly 163.0 163.0 April 1, 2028 501 Boylston Street (6) 3.70% paid monthly — 216.5 April 1, 2028 99 High Street 3.90% paid monthly 277.0 — March 1, 2030 Total Principal Outstanding $ 2,797.9 $ 2,238.6 Fair Value Adjustment (3) (54.7 ) (0.3 ) Total Mortgage Loans Payable $ 2,743.2 $ 2,238.3 (1) The mortgage is adjusted monthly for principal payments. (2) Interest rates are fixed. Some mortgages held by the Account are structured to begin principal and interest payments after an initial interest only period. (3) The fair value adjustment consists of the difference (positive or negative) between the principal amount of the outstanding debt and the fair value of the outstanding debt. See Note 1—Organization and Significant Accounting Policies. (4) Represents mortgage loans on these individual properties which are held within the Palomino Park portfolio. (5) This mortgage is comprised of three individual loans, all with equal recourse, interest rate and maturity. The principal balances by loan are $79.0 million , $45.0 million and $13.5 million . (6) On August 21, 2018 the Account sold a 49.9% interest in the property and transferred the remaining 50.1% to a joint venture investment.

Financial Highlights (Tables)

Financial Highlights (Tables)	9 Months Ended
	Sep. 30, 2018
Condensed Financial Information Disclosure [Abstract]
Schedule Of Condensed Financial Information For An Accumulation Unit of The Account	Selected condensed financial information for an Accumulation Unit of the Account is presented below. Per Accumulation Unit data is calculated on average units outstanding. For the Nine Months Ended September 30, 2018 Years Ended December 31, 2017 2016 2015 (Unaudited) Per Accumulation Unit Data: Rental income $ 13.487 $ 17.132 $ 16.433 $ 15.538 Real estate property level expenses and taxes 6.390 7.722 7.534 7.319 Real estate income, net 7.097 9.410 8.899 8.219 Other income 4.461 4.762 3.594 3.342 Total income 11.558 14.172 12.493 11.561 Expense charges (1) 2.402 3.318 3.290 3.092 Investment income, net 9.156 10.854 9.203 8.469 Net realized and unrealized gain on investments and mortgage loans payable 5.994 5.839 9.660 18.911 Net increase in Accumulation Unit Value 15.150 16.693 18.863 27.380 Accumulation Unit Value: Beginning of period 398.329 381.636 362.773 335.393 End of period $ 413.479 $ 398.329 $ 381.636 $ 362.773 Total return (3) 3.80 % 4.37 % 5.20 % 8.16 % Ratios to Average net assets (2) : Expenses (1) 0.78 % 0.83 % 0.86 % 0.86 % Investment income, net 2.97 % 2.72 % 2.41 % 2.37 % Portfolio turnover rate (3) : Real estate properties (4) 7.4 % 2.7 % 1.3 % 5.7 % Marketable securities (5) 3.3 % 5.7 % 3.5 % 10.0 % Accumulation Units outstanding at end of period (in millions) 60.7 61.3 62.4 60.4 Net assets end of period (in millions) $ 25,634.1 $ 24,942.6 $ 24,304.7 $ 22,360.0 (1) Expense charges per Accumulation Unit and the Ratio of Expenses to average net assets reflect the year to date Account level expenses and exclude real estate property level expenses which are included in real estate income, net. (2) Percentages for the nine months ended September 30, 2018 are annualized. (3) Percentages for the nine months ended September 30, 2018 are not annualized. (4) Real estate investment portfolio turnover rate is calculated by dividing the lesser of purchases or sales of real estate property investments (including contributions to, or return of capital distributions received from, existing joint venture and limited partnership investments) by the average value of the portfolio of real estate investments held during the period. (5) Marketable securities portfolio turnover rate is calculated by dividing the lesser of purchases or sales of securities, excluding securities having maturity dates at acquisition of one year or less, by the average value of the portfolio securities held during the period.

Accumulation Units (Tables)

Accumulation Units (Tables)	9 Months Ended
	Sep. 30, 2018
Accumulated Units Disclosure [Abstract]
Schedule Of Changes In The Number Of Accumulation Units Outstanding	Changes in the number of Accumulation Units outstanding were as follows (in millions): For the Nine Months Ended September 30, 2018 For the Year Ended December 31, 2017 (Unaudited) Outstanding: Beginning of period 61.3 62.4 Credited for premiums 4.7 6.6 Annuity, other periodic payments, withdrawals and death benefits (5.3 ) (7.7 ) End of period 60.7 61.3

Commitments and Contingencies -

Commitments and Contingencies - Schedule of Limited Partners' Callable Commitments (Tables)	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule Of Limited Partners' Callable Commitments	As of September 30, 2018 and December 31, 2017, the Account had the following immediately callable commitments to purchase additional interests in its limited partnership investments: September 30, 2018 December 31, 2017 (Unaudited) Taconic New York City GP Fund $ 26.0 $ 32.0 LCS SHIP Venture I, LLC 40.7 — $ 66.7 $ 32.0

Organization and Significant _3

Organization and Significant Accounting Policies - Narrative (Details)	9 Months Ended
	Sep. 30, 2018
Principal Transaction Revenue [Line Items]
Independent appraisal firm, property rotation, period (at least)	3 years
Description of valuation change of real estate related assets	Also, the independent fiduciary may require additional appraisals if factors or events have occurred that could materially change a property’s value (including those identified previously) and such change is not reflected in the quarterly valuation review, or otherwise to ensure that the Account is valued appropriately. The independent fiduciary must also approve any valuation change of real estate-related assets where a property’s value changed by more than 6% from the most recent independent annual appraisal, or if the value of the Account would change by more than 4% within any calendar quarter or more than 2% since the prior calendar month. When a real estate property is subject to a mortgage, the property is valued independently of the mortgage and the property and mortgage fair values are reported separately (see Valuation of Mortgage Loans Payable). The independent fiduciary reviews and approves all mortgage valuation adjustments before such adjustments are recorded by the Account. The Account continues to use the revised value for each real estate property and mortgage loan payable to calculate the Account’s daily net asset value until the next valuation review or appraisal.
Threshold percentage, property value change compared to most recent independent annual appraisal (more than)	6.00%
Threshold percentage, property value change within any calendar quarter (more than)	4.00%
Threshold percentage, property value change compared to prior calendar month (more than)	2.00%
Maximum percentage of average net assets for all account level expenses (not to exceed)	2.50%
Minimum cash collateral maintained, percentage (not less than)	100.00%
Minimum
Principal Transaction Revenue [Line Items]
Investment advisory fees, paid or received, period	1 day
Maximum
Principal Transaction Revenue [Line Items]
Investment advisory fees, paid or received, period	2 days

Related Party Transactions - Na

Related Party Transactions - Narrative (Details)	9 Months Ended
	Sep. 30, 2018
Related Party Transactions [Abstract]
Distribution Agreement, termination period	60 days

Concentrations of Risk - Narrat

Concentrations of Risk - Narrative (Details)	9 Months Ended
	Sep. 30, 2018lease_expiration
Risks and Uncertainties [Abstract]
Maximum percentage of annual contract rent of rental income (more than)	3.00%
Concentration Risk, Lease Expirations, Next Twelve Months	0

Concentrations of Risk - Schedu

Concentrations of Risk - Schedule of diversification of the Account's portfolio by region and property type (Details)	9 Months Ended
	Sep. 30, 2018
Concentration Risk [Line Items]
Concentration risk percentage	100.00%
Office
Concentration Risk [Line Items]
Concentration risk percentage	38.10%
Apartment
Concentration Risk [Line Items]
Concentration risk percentage	24.10%
Retail
Concentration Risk [Line Items]
Concentration risk percentage	19.70%
Industrial
Concentration Risk [Line Items]
Concentration risk percentage	14.70%
Other
Concentration Risk [Line Items]
Concentration risk percentage	3.40%
West
Concentration Risk [Line Items]
Concentration risk percentage	39.50%
West | Office
Concentration Risk [Line Items]
Concentration risk percentage	14.00%
West | Apartment
Concentration Risk [Line Items]
Concentration risk percentage	8.70%
West | Retail
Concentration Risk [Line Items]
Concentration risk percentage	8.10%
West | Industrial
Concentration Risk [Line Items]
Concentration risk percentage	8.10%
West | Other
Concentration Risk [Line Items]
Concentration risk percentage	0.60%
East
Concentration Risk [Line Items]
Concentration risk percentage	34.30%
East | Office
Concentration Risk [Line Items]
Concentration risk percentage	18.60%
East | Apartment
Concentration Risk [Line Items]
Concentration risk percentage	8.30%
East | Retail
Concentration Risk [Line Items]
Concentration risk percentage	3.10%
East | Industrial
Concentration Risk [Line Items]
Concentration risk percentage	1.70%
East | Other
Concentration Risk [Line Items]
Concentration risk percentage	2.60%
South
Concentration Risk [Line Items]
Concentration risk percentage	23.80%
South | Office
Concentration Risk [Line Items]
Concentration risk percentage	5.50%
South | Apartment
Concentration Risk [Line Items]
Concentration risk percentage	6.00%
South | Retail
Concentration Risk [Line Items]
Concentration risk percentage	7.80%
South | Industrial
Concentration Risk [Line Items]
Concentration risk percentage	4.40%
South | Other
Concentration Risk [Line Items]
Concentration risk percentage	0.10%
Midwest
Concentration Risk [Line Items]
Concentration risk percentage	2.40%
Midwest | Office
Concentration Risk [Line Items]
Concentration risk percentage	0.00%
Midwest | Apartment
Concentration Risk [Line Items]
Concentration risk percentage	1.10%
Midwest | Retail
Concentration Risk [Line Items]
Concentration risk percentage	0.70%
Midwest | Industrial
Concentration Risk [Line Items]
Concentration risk percentage	0.50%
Midwest | Other
Concentration Risk [Line Items]
Concentration risk percentage	0.10%

Assets and Liabilities Measur_3

Assets and Liabilities Measured at Fair Value on a Recurring Basis - Schedule of fair value assets and liabilities measured on recurring basis (Details) - USD ($) $ in Millions		Sep. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Real estate properties		$ 15,345.9	$ 15,742.7
Marketable securities:
Real estate-related	[1]	1,430.6	1,238
Marketable Securities Excluding Real Estate		4,844.7	3,887.5
Total investments (cost: $24,069.9 and $22,823.6)		28,412.5	27,170
Mortgage loans payable		(2,743.2)	(2,238.3)
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Real estate properties		15,345.9	15,742.7
Real estate joint ventures		5,795.3	5,860.6
Limited partnerships		140.9	142.4
Marketable securities:
Real estate-related		1,430.6	1,238
Loans receivable		855.1	298.8
Total investments (cost: $24,069.9 and $22,823.6)		28,412.5	27,170
Mortgage loans payable		(2,743.2)	(2,238.3)
Fair Value, Measurements, Recurring | Government agency notes
Marketable securities:
Marketable Securities Excluding Real Estate		2,560.7	2,872.3
Fair Value, Measurements, Recurring | United States Treasury securities
Marketable securities:
Marketable Securities Excluding Real Estate		2,284	1,015.2
Fair Value, Measurements, Recurring | Level 1: Quoted Prices in Active Markets for Identical Assets
Marketable securities:
Real estate-related		1,430.6	1,238
Total investments (cost: $24,069.9 and $22,823.6)		1,430.6	1,238
Fair Value, Measurements, Recurring | Level 2: Significant Other Observable Inputs
Marketable securities:
Total investments (cost: $24,069.9 and $22,823.6)		4,844.7	3,887.5
Fair Value, Measurements, Recurring | Level 2: Significant Other Observable Inputs | Government agency notes
Marketable securities:
Marketable Securities Excluding Real Estate		2,560.7	2,872.3
Fair Value, Measurements, Recurring | Level 2: Significant Other Observable Inputs | United States Treasury securities
Marketable securities:
Marketable Securities Excluding Real Estate		2,284	1,015.2
Fair Value, Measurements, Recurring | Level 3: Significant Unobservable Inputs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Real estate properties		15,345.9	15,742.7
Real estate joint ventures		5,795.3	5,860.6
Marketable securities:
Loans receivable		855.1	298.8
Total investments (cost: $24,069.9 and $22,823.6)		21,996.3	21,902.1
Mortgage loans payable		$ (2,743.2)	$ (2,238.3)
[1]	Includes securities loaned of $6.4 million at September 30, 2018 and $18.1 million at December 31, 2017.

Assets and Liabilities Measur_4

Assets and Liabilities Measured at Fair Value on a Recurring Basis - Schedule of fair value assets and liabilities measured on recurring basis using unobservable inputs (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total realized and unrealized gains (losses) included in changes in net assets	$ 31.1	$ 87.3	$ 233.4	$ 221.1
Mortgage Loans Payable
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	(2,891.4)	(2,290.1)	(2,238.3)	(2,332.1)
Total realized and unrealized gains included in changes in net assets	(0.8)	(4.1)	54.4	(10.6)
Purchases	(72)	(17.7)	(817.9)	(17.7)
Settlements	221	0.9	258.6	49.4
Ending balance	(2,743.2)	(2,311)	(2,743.2)	(2,311)
Real Estate Properties
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	16,042.7	15,496.6	15,742.7	15,452.8
Total realized and unrealized gains (losses) included in changes in net assets	114.6	65.8	212.9	133.2
Purchases	253.7	317.1	830.3	408.9
Sales	(1,065.1)	(225.3)	(1,440)	(340.7)
Ending balance	15,345.9	15,654.2	15,345.9	15,654.2
Real Estate Joint Ventures
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	5,915.3	5,946.8	5,860.6	5,622.4
Total realized and unrealized gains (losses) included in changes in net assets	7.5	17.6	99.1	80.4
Purchases	242.1	13.1	325.9	275.6
Settlements	(369.6)	(302.1)	(490.3)	(303)
Ending balance	5,795.3	5,675.4	5,795.3	5,675.4
Loans Receivable
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	618.3	297.3	298.8	295.7
Total realized and unrealized gains (losses) included in changes in net assets	1	1.4	1	1.4
Purchases	380.1	0.1	699.6	1.7
Settlements	(144.3)	0	(144.3)	0
Ending balance	855.1	298.8	855.1	298.8
Total Level 3 Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	22,576.3	21,740.7	21,902.1	21,370.9
Total realized and unrealized gains (losses) included in changes in net assets	123.1	84.8	313	215
Purchases	875.9	330.3	1,855.8	686.2
Sales	(1,065.1)	(225.3)	(1,440)	(340.7)
Settlements	(513.9)	(302.1)	(634.6)	(303)
Ending balance	$ 21,996.3	$ 21,628.4	$ 21,996.3	$ 21,628.4

Assets and Liabilities Measur_5

Assets and Liabilities Measured at Fair Value on a Recurring Basis - Schedule of unobservable inputs related to Level 3 fair value measurements (Details) - Level 3: Significant Unobservable Inputs	Sep. 30, 2018	Sep. 30, 2017
Discount Rate | Real Estate Properties and Joint Ventures | Office | Minimum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.055	0.055
Discount Rate | Real Estate Properties and Joint Ventures | Office | Maximum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.086	0.083
Discount Rate | Real Estate Properties and Joint Ventures | Office | Weighted Average | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.065	0.065
Discount Rate | Real Estate Properties and Joint Ventures | Industrial | Minimum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.055	0.057
Discount Rate | Real Estate Properties and Joint Ventures | Industrial | Maximum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.089	0.086
Discount Rate | Real Estate Properties and Joint Ventures | Industrial | Weighted Average | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.068	0.066
Discount Rate | Real Estate Properties and Joint Ventures | Apartment | Minimum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.053	0.053
Discount Rate | Real Estate Properties and Joint Ventures | Apartment | Maximum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.078	0.073
Discount Rate | Real Estate Properties and Joint Ventures | Apartment | Weighted Average | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.063	0.062
Discount Rate | Real Estate Properties and Joint Ventures | Retail | Minimum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.050	0.050
Discount Rate | Real Estate Properties and Joint Ventures | Retail | Maximum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.105	0.104
Discount Rate | Real Estate Properties and Joint Ventures | Retail | Weighted Average | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.064	0.064
Capitalization Rate | Real Estate Properties and Joint Ventures | Office | Minimum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.040	0.043
Capitalization Rate | Real Estate Properties and Joint Ventures | Office | Minimum | Direct Capitalization
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.040	0.038
Capitalization Rate | Real Estate Properties and Joint Ventures | Office | Maximum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.075	0.073
Capitalization Rate | Real Estate Properties and Joint Ventures | Office | Maximum | Direct Capitalization
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.070	0.070
Capitalization Rate | Real Estate Properties and Joint Ventures | Office | Weighted Average | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.055	0.055
Capitalization Rate | Real Estate Properties and Joint Ventures | Office | Weighted Average | Direct Capitalization
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.049	0.046
Capitalization Rate | Real Estate Properties and Joint Ventures | Industrial | Minimum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.045	0.048
Capitalization Rate | Real Estate Properties and Joint Ventures | Industrial | Minimum | Direct Capitalization
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.040	0.040
Capitalization Rate | Real Estate Properties and Joint Ventures | Industrial | Maximum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.080	0.080
Capitalization Rate | Real Estate Properties and Joint Ventures | Industrial | Maximum | Direct Capitalization
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.075	0.075
Capitalization Rate | Real Estate Properties and Joint Ventures | Industrial | Weighted Average | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.056	0.055
Capitalization Rate | Real Estate Properties and Joint Ventures | Industrial | Weighted Average | Direct Capitalization
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.050	0.049
Capitalization Rate | Real Estate Properties and Joint Ventures | Apartment | Minimum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.038	0.038
Capitalization Rate | Real Estate Properties and Joint Ventures | Apartment | Minimum | Direct Capitalization
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.033	0.033
Capitalization Rate | Real Estate Properties and Joint Ventures | Apartment | Maximum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.063	0.060
Capitalization Rate | Real Estate Properties and Joint Ventures | Apartment | Maximum | Direct Capitalization
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.058	0.055
Capitalization Rate | Real Estate Properties and Joint Ventures | Apartment | Weighted Average | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.050	0.048
Capitalization Rate | Real Estate Properties and Joint Ventures | Apartment | Weighted Average | Direct Capitalization
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.045	0.042
Capitalization Rate | Real Estate Properties and Joint Ventures | Retail | Minimum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.043	0.043
Capitalization Rate | Real Estate Properties and Joint Ventures | Retail | Minimum | Direct Capitalization
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.038	0.038
Capitalization Rate | Real Estate Properties and Joint Ventures | Retail | Maximum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.088	0.085
Capitalization Rate | Real Estate Properties and Joint Ventures | Retail | Maximum | Direct Capitalization
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.105	0.083
Capitalization Rate | Real Estate Properties and Joint Ventures | Retail | Weighted Average | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.052	0.052
Capitalization Rate | Real Estate Properties and Joint Ventures | Retail | Weighted Average | Direct Capitalization
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Real Estate Properties and Joint Ventures	0.046	0.047
Loan to Value Ratio | Mortgage Loans Payable | Apartment | Minimum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	0.323	0.295
Loan to Value Ratio | Mortgage Loans Payable | Apartment | Minimum | Net Present Value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	0.323	0.295
Loan to Value Ratio | Mortgage Loans Payable | Apartment | Maximum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	0.639	0.612
Loan to Value Ratio | Mortgage Loans Payable | Apartment | Maximum | Net Present Value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	0.639	0.612
Loan to Value Ratio | Mortgage Loans Payable | Apartment | Weighted Average | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	0.472	0.416
Loan to Value Ratio | Mortgage Loans Payable | Apartment | Weighted Average | Net Present Value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	0.472	0.416
Loan to Value Ratio | Mortgage Loans Payable | Retail | Minimum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	0.176	0.183
Loan to Value Ratio | Mortgage Loans Payable | Retail | Minimum | Net Present Value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	0.176	0.183
Loan to Value Ratio | Mortgage Loans Payable | Retail | Maximum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	0.553	0.511
Loan to Value Ratio | Mortgage Loans Payable | Retail | Maximum | Net Present Value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	0.553	0.551
Loan to Value Ratio | Mortgage Loans Payable | Retail | Weighted Average | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	0.332	0.313
Loan to Value Ratio | Mortgage Loans Payable | Retail | Weighted Average | Net Present Value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	0.332	0.313
Loan to Value Ratio | Mortgage Loans Payable | Office and Industrial | Minimum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	0.377	0.385
Loan to Value Ratio | Mortgage Loans Payable | Office and Industrial | Minimum | Net Present Value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	0.377	0.385
Loan to Value Ratio | Mortgage Loans Payable | Office and Industrial | Maximum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	0.707	0.684
Loan to Value Ratio | Mortgage Loans Payable | Office and Industrial | Maximum | Net Present Value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	0.707	0.684
Loan to Value Ratio | Mortgage Loans Payable | Office and Industrial | Weighted Average | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	0.432	0.437
Loan to Value Ratio | Mortgage Loans Payable | Office and Industrial | Weighted Average | Net Present Value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	0.432	0.437
Loan to Value Ratio | Loans Receivable | Office, Retail and Storage | Minimum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans Receivable	0.708	0.589
Loan to Value Ratio | Loans Receivable | Office, Retail and Storage | Maximum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans Receivable	0.792	0.792
Loan to Value Ratio | Loans Receivable | Office, Retail and Storage | Weighted Average | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans Receivable	0.758	0.759
Equivalency Rate | Mortgage Loans Payable | Apartment | Minimum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	0.040	0.029
Equivalency Rate | Mortgage Loans Payable | Apartment | Maximum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	0.044	0.036
Equivalency Rate | Mortgage Loans Payable | Apartment | Weighted Average | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	0.042	0.033
Equivalency Rate | Mortgage Loans Payable | Retail | Minimum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	0.041	0.030
Equivalency Rate | Mortgage Loans Payable | Retail | Maximum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	0.052	0.045
Equivalency Rate | Mortgage Loans Payable | Retail | Weighted Average | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	0.044	0.036
Equivalency Rate | Mortgage Loans Payable | Office and Industrial | Minimum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	0.037	0.037
Equivalency Rate | Mortgage Loans Payable | Office and Industrial | Maximum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	0.060	0.046
Equivalency Rate | Mortgage Loans Payable | Office and Industrial | Weighted Average | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	0.044	0.039
Equivalency Rate | Loans Receivable | Office, Retail and Storage | Minimum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans Receivable	0.042	0.042
Equivalency Rate | Loans Receivable | Office, Retail and Storage | Maximum | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans Receivable	0.083	0.083
Equivalency Rate | Loans Receivable | Office, Retail and Storage | Weighted Average | Discounted Cash Flow
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Loans Receivable	0.057	0.063
Weighted Average Cost of Capital Risk Premium Multiple | Mortgage Loans Payable | Apartment | Minimum | Net Present Value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	1.20	1.20
Weighted Average Cost of Capital Risk Premium Multiple | Mortgage Loans Payable | Apartment | Maximum | Net Present Value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	1.40	1.50
Weighted Average Cost of Capital Risk Premium Multiple | Mortgage Loans Payable | Apartment | Weighted Average | Net Present Value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	1.30	1.30
Weighted Average Cost of Capital Risk Premium Multiple | Mortgage Loans Payable | Retail | Minimum | Net Present Value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	1.10	1.10
Weighted Average Cost of Capital Risk Premium Multiple | Mortgage Loans Payable | Retail | Maximum | Net Present Value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	1.30	1.30
Weighted Average Cost of Capital Risk Premium Multiple | Mortgage Loans Payable | Retail | Weighted Average | Net Present Value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	1.20	1.20
Weighted Average Cost of Capital Risk Premium Multiple | Mortgage Loans Payable | Office and Industrial | Minimum | Net Present Value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	1.20	1.20
Weighted Average Cost of Capital Risk Premium Multiple | Mortgage Loans Payable | Office and Industrial | Maximum | Net Present Value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	1.50	1.50
Weighted Average Cost of Capital Risk Premium Multiple | Mortgage Loans Payable | Office and Industrial | Weighted Average | Net Present Value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage Loans Payable	1.30	1.30

Assets and Liabilities Measur_6

Assets and Liabilities Measured at Fair Value on a Recurring Basis - Schedule of net unrealized gains included in changes in net assets attributable to investments and mortgage loans payable (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total realized and unrealized gains included in changes in net assets	$ 31.1	$ 87.3	$ 233.4	$ 221.1
Mortgage Loans Payable
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total realized and unrealized gains included in changes in net assets	4.8	(4.1)	60	(10.6)
Real Estate Properties
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total realized and unrealized gains included in changes in net assets	48.1	68	158.8	139
Real Estate Joint Ventures
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total realized and unrealized gains included in changes in net assets	(18.1)	17.9	73.5	80.7
Loans Receivable
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total realized and unrealized gains included in changes in net assets	$ 1.1	$ 1.4	$ 1.1	$ 1.4

Investments in Joint Ventures -

Investments in Joint Ventures - Narrative (Details) - USD ($) $ in Billions	Sep. 30, 2018	Dec. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
Minimum percentage of noncontrolling ownership interest In joint ventures	33.30%
Maximum percentage of noncontrolling ownership interest in joint ventures	97.50%
Equity investments fair value joint ventures	$ 5.8	$ 5.9

Investments in Joint Ventures_2

Investments in Joint Ventures - Schedule of Results of Operations of the Joint Ventures (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Operating Revenue and Expenses
Revenues	$ 237.2	$ 218	$ 694.2	$ 645
Expenses	122.8	108.3	381	315
Excess of revenues over expenses	$ 114.4	$ 109.7	$ 313.2	$ 330

Investments in Limited Partne_2

Investments in Limited Partnerships - Narrative (Details)	9 Months Ended
	Sep. 30, 2018
Clarion Gables Multi-Family LP
Limited Partners' Capital Account [Line Items]
Advanced notice redemption period (or more)	3 months

Mortgage Loans Payable - Schedu

Mortgage Loans Payable - Schedule of Outstanding Mortgage Loans Payable Secured by Properties (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Principal amounts outstanding	$ 2,797.9	$ 2,238.6
Fair value adjustment	(54.7)	(0.3)
Total Mortgage Loans Payable	$ 2,743.2	2,238.3
Mass Court
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	2.88%
Annual interest rate and payment frequency	2.88% paid monthly
Principal amounts outstanding	$ 90.7	92.1
Maturity	Sep. 1, 2019
Red Canyon at Palomino Park
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	5.34%
Annual interest rate and payment frequency	5.34% paid monthly
Principal amounts outstanding	$ 27.1	27.1
Maturity	Aug. 1, 2020
Green River at Palomino Park
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	5.34%
Annual interest rate and payment frequency	5.34% paid monthly
Principal amounts outstanding	$ 33.2	33.2
Maturity	Aug. 1, 2020
Blue Ridge at Palomino Park
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	5.34%
Annual interest rate and payment frequency	5.34% paid monthly
Principal amounts outstanding	$ 33.4	33.4
Maturity	Aug. 1, 2020
Ashford Meadows Apartments
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	5.17%
Annual interest rate and payment frequency	5.17% paid monthly
Principal amounts outstanding	$ 44.6	44.6
Maturity	Aug. 1, 2020
The Knoll
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	3.98%
Annual interest rate and payment frequency	3.98% paid monthly
Principal amounts outstanding	$ 17.1	17.5
Maturity	Dec. 5, 2020
The Corner
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	4.66%
Annual interest rate and payment frequency	4.66% paid monthly
Principal amounts outstanding	$ 105	105
Maturity	Jun. 1, 2021
Ascent at Windward
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	3.51%
Annual interest rate and payment frequency	3.51% paid monthly
Principal amounts outstanding	$ 34.6	0
Maturity	Jan. 1, 2022
The Palatine
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	4.25%
Annual interest rate and payment frequency	4.25% paid monthly
Principal amounts outstanding	$ 77.7	78.8
Maturity	Jan. 10, 2022
The Forum at Carlsbad
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	4.25%
Annual interest rate and payment frequency	4.25% paid monthly
Principal amounts outstanding	$ 87.7	88.9
Maturity	Mar. 1, 2022
Fusion 1,560
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	3.42%
Annual interest rate and payment frequency	3.42% paid monthly
Principal amounts outstanding	$ 37.4	0
Maturity	Jun. 10, 2022
The Colorado
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	3.69%
Annual interest rate and payment frequency	3.69% paid monthly
Principal amounts outstanding	$ 90.3	91.7
Maturity	Nov. 1, 2022
The Legacy at Westwood
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	3.69%
Annual interest rate and payment frequency	3.69% paid monthly
Principal amounts outstanding	$ 46.1	46.7
Maturity	Nov. 1, 2022
Regents Court
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	3.69%
Annual interest rate and payment frequency	3.69% paid monthly
Principal amounts outstanding	$ 39.1	39.6
Maturity	Nov. 1, 2022
Fourth And Madison | Loan A
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	3.75%
Annual interest rate and payment frequency	3.75% paid monthly
Principal amounts outstanding	$ 199.1	200
Maturity	Jun. 1, 2023
Fourth And Madison | Loan B
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	4.17%
Annual interest rate and payment frequency	4.17% paid monthly
Principal amounts outstanding	$ 90	0
Maturity	Jun. 1, 2023
1001 Pennsylvania Avenue
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	3.70%
Annual interest rate and payment frequency	3.70% paid monthly
Principal amounts outstanding	$ 328.5	330
Maturity	Jun. 1, 2023
Biltmore at Midtown
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	3.94%
Annual interest rate and payment frequency	3.94% paid monthly
Principal amounts outstanding	$ 36.4	0
Maturity	Jul. 5, 2023
Cherry Knoll
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	3.78%
Annual interest rate and payment frequency	3.78% paid monthly
Principal amounts outstanding	$ 35.3	0
Maturity	Jul. 5, 2023
Lofts at SoDo
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	3.94%
Annual interest rate and payment frequency	3.94% paid monthly
Principal amounts outstanding	$ 35.1	0
Maturity	Jul. 5, 2023
1401 H Street NW
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	3.65%
Annual interest rate and payment frequency	3.65% paid monthly
Principal amounts outstanding	$ 115	115
Maturity	Nov. 5, 2024
Circa Green Lake
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	3.71%
Annual interest rate and payment frequency	3.71% paid monthly
Principal amounts outstanding	$ 52	0
Maturity	Mar. 5, 2025
Union - South Lake Union
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	3.66%
Annual interest rate and payment frequency	3.66% paid monthly
Principal amounts outstanding	$ 57	0
Maturity	Mar. 5, 2025
Holly Street Village
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	3.65%
Annual interest rate and payment frequency	3.65% paid monthly
Principal amounts outstanding	$ 81	0
Maturity	May 1, 2025
Township Apartments
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	3.65%
Annual interest rate and payment frequency	3.65% paid monthly
Principal amounts outstanding	$ 49	0
Maturity	May 1, 2025
32 South State Street
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	4.48%
Annual interest rate and payment frequency	4.48% paid monthly
Principal amounts outstanding	$ 24	24
Maturity	Jun. 6, 2025
780 Third Avenue | Loan A
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	3.55%
Annual interest rate and payment frequency	3.55% paid monthly
Principal amounts outstanding	$ 150	150
Maturity	Aug. 1, 2025
780 Third Avenue | Loan B
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	3.55%
Annual interest rate and payment frequency	3.55% paid monthly
Principal amounts outstanding	$ 20	20
Maturity	Aug. 1, 2025
701 Brickell Avenue
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	3.66%
Annual interest rate and payment frequency	3.66% paid monthly
Principal amounts outstanding	$ 184	184
Maturity	Apr. 1, 2026
55 Second Street
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	3.74%
Annual interest rate and payment frequency	3.74% paid monthly
Principal amounts outstanding	$ 137.5	137.5
Maturity	Oct. 1, 2026
1900 K Street, NW
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	3.93%
Annual interest rate and payment frequency	3.93% paid monthly
Principal amounts outstanding	$ 163	163
Maturity	Apr. 1, 2028
501 Boylston Street
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	3.70%
Annual interest rate and payment frequency	3.70% paid monthly
Principal amounts outstanding	$ 0	216.5
Maturity	Apr. 1, 2028
99 High Street
Mortgage Loans Payable - Schedule of outstanding mortgage loans payable secured by properties [Line Items]
Annual interest rate	3.90%
Annual interest rate and payment frequency	3.90% paid monthly
Principal amounts outstanding	$ 277	$ 0
Maturity	Mar. 1, 2030

Mortgage Loans Payable - Narrat

Mortgage Loans Payable - Narrative (Details) $ in Millions	9 Months Ended
	Sep. 30, 2018USD ($)loan	Aug. 21, 2018	Dec. 31, 2017USD ($)
Mortgage Loans Payable [Line Items]
Principal balances by loan	$ 2,797.9		$ 2,238.6
Second Street
Mortgage Loans Payable [Line Items]
Mortgage loans on real estate, number of individual loans | loan	3
Principal balances by loan	$ 137.5		137.5
Second Street | Loan One
Mortgage Loans Payable [Line Items]
Principal balances by loan	79
Second Street | Loan Two
Mortgage Loans Payable [Line Items]
Principal balances by loan	45
Second Street | Loan Three
Mortgage Loans Payable [Line Items]
Principal balances by loan	13.5
501 Boylston Street
Mortgage Loans Payable [Line Items]
Principal balances by loan	$ 0		$ 216.5
Percentage of interest in the property sold		49.90%
Percentage of interest in the property transferred to joint venture investment		50.10%

Line of Credit - Narrative (Det

Line of Credit - Narrative (Details) - Unsecured Revolving Credit Facility - Line of Credit	Sep. 20, 2018USD ($)loanterminstitution	Sep. 30, 2018USD ($)
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 500,000,000
Number of financial institutions | institution	4
Maximum borrowing capacity, per lender	$ 125,000,000
Number of extension periods | term	2
Extension period	12 months
Additional borrowing capacity	$ 250,000,000
Unused commitment fee, percentage	0.20%
Line of credit		$ 0
Eurodollar Loan
Debt Instrument [Line Items]
Minimum funding requirement	$ 5,000,000
Line of credit, term (or less)	12 months
Maximum active loan limit | loan	5
Eurodollar Loan | Minimum | Adjusted LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	0.85%
Eurodollar Loan | Maximum | Adjusted LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	1.05%
Alternate Base Rate Loan
Debt Instrument [Line Items]
Minimum funding requirement	$ 5,000,000
Alternate Base Rate Loan | Adjusted LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	1.00%
Alternate Base Rate Loan | Federal Reserve Bank of New York
Debt Instrument [Line Items]
Basis spread on variable rate	0.50%

Financial Highlights - Schedule

Financial Highlights - Schedule of condensed financial information for an accumulation unit of the account (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jun. 30, 2018	Sep. 30, 2017	Jun. 30, 2017
Per Accumulation Unit Data:
Rental income (in dollars per share)	$ 13.487	$ 17.132	$ 16.433	$ 15.538
Real estate property level expenses and taxes (in dollars per share)	6.390	7.722	7.534	7.319
Real estate income, net (in dollars per share)	7.097	9.410	8.899	8.219
Other income (in dollars per share)	4.461	4.762	3.594	3.342
Total income (in dollars per share)	11.558	14.172	12.493	11.561
Expense charges (in dollars per share)	2.402	3.318	3.290	3.092
Investment income, net (in dollars per share)	9.156	10.854	9.203	8.469
Net realized and unrealized gain on investments and mortgage loans payable (in dollars per share)	5.994	5.839	9.660	18.911
Net increase in Accumulation Unit Value (in dollars per share)	15.150	16.693	18.863	27.380
Accumulation Unit Value:
Beginning of period (in dollars per share)	398.329	381.636	362.773	335.393
End of period (in dollars per share)	$ 413.479	$ 398.329	$ 381.636	$ 362.773
Total return	3.80%	4.37%	5.20%	8.16%
Ratios to Average net assets:
Expenses	0.78%	0.83%	0.86%	0.86%
Investment income, net	2.97%	2.72%	2.41%	2.37%
Portfolio turnover rate:
Real estate properties	7.40%	2.70%	1.30%	5.70%
Marketable securities	3.30%	5.70%	3.50%	10.00%
Accumulation Units outstanding at end of period (in millions) (in shares)	60.7	61.3	62.4	60.4
Net assets end of period (in millions)	$ 25,634.1	$ 24,942.6	$ 24,304.7	$ 22,360	$ 25,300.5	$ 24,839.8	$ 24,808.9

Accumulation Units - Schedule o

Accumulation Units - Schedule of changes in the number of accumulation units outstanding (Details) - shares shares in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Outstanding:
Beginning of period (in shares)	61.3	62.4
Credited for premiums (in shares)	4.7	6.6
Annuity, other periodic payments, withdrawals and death benefits (in shares)	(5.3)	(7.7)
End of period (in shares)	60.7	61.3

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Limited Partners' Callable Commitments (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Limited Partners' Capital Account [Line Items]
Callable commitments amount	$ 66.7	$ 32
Taconic New York City GP Fund
Limited Partners' Capital Account [Line Items]
Callable commitments amount	26	32
LCS SHIP Venture I, LLC
Limited Partners' Capital Account [Line Items]
Callable commitments amount	$ 40.7	$ 0

Commitments and Contingencies_3

Commitments and Contingencies - Narrative (Details)	9 Months Ended
	Sep. 30, 2018anniversary
Commitments and Contingencies Disclosure [Abstract]
Commitment period anniversary from closing	5
Right to close commitment period early, percentage of commitment satisfied	90.00%