Fair Value

12 Months Ended

Dec. 31, 2011

Fair Value

11.  Fair Value

Fair Value Methodology

As a basis for applying a market-based approach in fair value measurements, GAAP establishes a fair value hierarchy that distinguishes between market participant assumptions based on market data obtained from sources independent of the reporting entity and the reporting entity’s own assumptions about market participant assumptions. The valuation of financial instruments can be determined using widely accepted valuation techniques.

The Company applies valuation models such as discounted cash flow analysis on the expected cash flows of each instrument which considers the contractual terms of the instruments, including the period to maturity, and uses observable market-based inputs, including interest rate curves and market prices, as available and applicable. In addition, the Company incorporates credit valuation adjustments to appropriately reflect both its own nonperformance risk and the respective counterparty’s nonperformance risk in the fair value measurements as discussed below. When market-based inputs are not available in valuing the Company’s financial instruments, such as for valuing redeemable noncontrolling interests, the Company uses unobservable inputs considering the assumptions that market participants would make in deriving the fair value. The use of different market assumptions and/or estimation methodologies may have a material effect on the Company’s estimates of fair value.

Financial Instruments Carried at Fair Value

Derivative Financial Instruments

Currently, the Company uses interest rate swap and interest rate cap agreements to manage its interest rate risk. These instruments are carried at fair value in the Company’s financial statements. See Note 5, “Derivative Instruments and Hedging Activities,” for derivative values at December 31, 2011 and a description of where these amounts are recorded in the financial statements. In adjusting the fair value of its derivative contracts for the effect of counterparty nonperformance risk, the Company has considered the impact of its net position with a given counterparty, as well as any applicable credit enhancements, such as collateral postings, thresholds, mutual puts, and guarantees. Although the Company has determined that the majority of the inputs used to value its derivatives fall within Level 2 of the fair value hierarchy, the credit valuation adjustments associated with its derivatives use Level 3 inputs, such as estimates of current credit spreads, to evaluate the likelihood of default by itself and its counterparties. As of December 31, 2011, the Company assessed the significance of the impact of the credit valuation adjustments on the overall valuation of its derivative positions and has determined it is not significant. As a result, the Company has determined that its derivative valuations are classified in Level 2 of the fair value hierarchy.

Redeemable Noncontrolling Interests

Redeemable noncontrolling interests are reported at fair value, with reductions in fair value recorded only to the extent that the Company has previously recorded increases in fair value above the redeemable noncontrolling interests’ initial basis.

• Puts – The Company provided redemption options (the “Puts”) that allow two of the Company’s joint venture partners to require the Company to purchase their interests in the investments at the future fair market value. In 2011, the Company acquired the noncontrolling interest associated with a consolidated community for $9,070,000 satisfying its obligation under one of the Puts. The remaining Put is payable in cash or, at the Company’s option, common stock of the Company. The Company determines the fair value of the Put based on unobservable inputs considering the assumptions that market participants would make in pricing the obligations. The Company applies discount factors to the estimated future cash flows of the asset underlying the associated joint venture, which in the case of the Put is the NOI from an apartment community, as well as potential disposition proceeds utilizing market capitalization rates, to derive the fair value of the position. Given the significance of the unobservable inputs, the valuations are classified in Level 3 of the fair value hierarchy. At December 31, 2010, the Puts’ aggregate fair value was $12,106,000. At December 31, 2011, the aggregate fair value of the remaining outstanding Put was $5,648,000.

• DownREIT units – The Company issued units of limited partnership interest in DownREITs which provide the DownREIT limited partners the ability to present all or some of their units for redemption for a cash amount as determined by the applicable partnership agreement. Under the DownREIT agreements, for each limited partnership unit, the limited partner is entitled to receive cash in the amount equal to the fair value of the Company’s common stock on or about the date of redemption. In lieu of cash redemption, the Company may elect to exchange such units for an equal number of shares in the Company’s common stock. The limited partnership units in DownREITs are valued using the market price of the Company’s common stock, a Level 1 price under the fair value hierarchy. At December 31, 2010, the fair value of the DownREIT units was $1,721,000. At December 31, 2011, the fair value of the DownREIT units was $980,000.

Financial Instruments Not Carried at Fair Value

Cash and Cash Equivalents

Cash and cash equivalent balances are held with various financial institutions within principal protected accounts. The Company monitors credit ratings of these financial institutions and the concentration of cash and cash equivalent balances with any one financial institution and believes the likelihood of realizing material losses related to cash and cash equivalent balances is remote. Cash and cash equivalents are carried at their face amounts, which reasonably approximate their fair values.

Other Financial Instruments

Rents receivable, accounts and construction payable and accrued expenses and other liabilities are carried at their face amounts, which reasonably approximate their fair values.

The Company values its bond indebtedness, notes payable and outstanding amounts under the Credit Facility using a discounted cash flow analysis on the expected cash flows of each instrument. This analysis reflects the contractual terms of the instrument, including the period to maturity, and uses observable market-based inputs, including interest rate curves. The process also considers credit valuation adjustments to appropriately reflect the Company’s nonperformance risk. The Company has concluded that the value of its bond indebtedness and notes payable are Level 2 prices as the majority of the inputs used to value its positions fall within Level 2 of the fair value hierarchy. Bond indebtedness, notes payable and outstanding amounts under the Credit Facility (as applicable) with an aggregate outstanding par amount of approximately $3,633,125,000 and $4,068,417,000 had an estimated aggregate fair value of $3,838,360,000 and $4,236,216,000 at December 31, 2011 and December 31, 2010, respectively.