Variable Interest Entities	3 Months Ended
Mar. 31, 2012
Organization/Basis of Presentation and Summary of Significant Accounting Policies [Abstract]
Variable Interest Entities	NOTE 5 — Variable Interest Entities As of March 31, 2012, we were the primary beneficiary of, and therefore consolidated, 119 VIEs, which owned 81 apartment properties with 12,768 units. Real estate with a carrying value of $778.4 million collateralized $632.6 million of debt of those VIEs. Any significant amounts of assets and liabilities related to our consolidated VIEs are identified parenthetically on our accompanying condensed consolidated balance sheets. The creditors of the consolidated VIEs do not have recourse to our general credit. As of March 31, 2012, we also held variable interests in 178 VIEs for which we were not the primary beneficiary. Those VIEs consist primarily of partnerships that are engaged, directly or indirectly, in the ownership and management of 231 apartment properties with 12,331 units. We are involved with those VIEs as an equity holder, lender, management agent, or through other contractual relationships. Approximately $22.5 million of our investment in unconsolidated VIEs at March 31, 2012, are held through consolidated partnerships that are VIEs and in which we generally hold a 1% or less general partner or equivalent interest. Accordingly, substantially all of the investment balances related to these unconsolidated VIEs are attributed to the noncontrolling interests in the consolidated investment partnerships that hold the investments in these unconsolidated VIEs. Our maximum risk of loss related to our investment in these VIEs is generally limited to our equity interest in the consolidated investment partnerships, which is insignificant. The remainder of our investment in unconsolidated VIEs, or approximately $5.2 million at March 31, 2012, is held through consolidated investment partnerships that are VIEs and in which we hold substantially all of the economic interests. Our maximum risk of loss related to our investment in these VIEs is limited to our $5.2 million recorded investment in such entities. As discussed in Note 1, we have entered into an agreement to sell our interests in a portfolio of properties upon satisfaction of certain conditions and regulatory approvals. As of March 31, 2012, this portfolio included 42 consolidated VIEs that owned 18 properties and 130 unconsolidated VIEs that owned 130 properties. In addition to our investments in unconsolidated VIEs discussed above, at March 31, 2012, we had in aggregate $96.9 million of receivables from unconsolidated VIEs (primarily notes receivable collateralized by second mortgages on real estate properties as further discussed in Note 10) and we had a contractual obligation to advance funds to certain unconsolidated VIEs totaling $3.0 million. Our maximum risk of loss associated with our lending and management activities related to these unconsolidated VIEs is limited to these amounts. We may be subject to additional losses to the extent of any receivables relating to future provision of services to these entities or financial support that we voluntarily provide. As discussed in Note 8, noncompliance with applicable requirements related to our consolidated and unconsolidated tax credit partnerships, substantially all of which are VIEs, could result in projected tax credits not being realized and require a refund of investor contributions already received or a reduction of future investor contributions. We have not historically had, nor do we anticipate, any material refunds or reductions of investor capital contributions in connection with these arrangements.

Variable Interest Entities

3 Months Ended

Mar. 31, 2012

Organization/Basis of Presentation and Summary of Significant Accounting Policies [Abstract]

NOTE 5 — Variable Interest Entities

As of March 31, 2012, we were the primary beneficiary of, and therefore consolidated, 119 VIEs, which owned 81 apartment properties with 12,768 units. Real estate with a carrying value of $778.4 million collateralized $632.6 million of debt of those VIEs. Any significant amounts of assets and liabilities related to our consolidated VIEs are identified parenthetically on our accompanying condensed consolidated balance sheets. The creditors of the consolidated VIEs do not have recourse to our general credit.

As of March 31, 2012, we also held variable interests in 178 VIEs for which we were not the primary beneficiary. Those VIEs consist primarily of partnerships that are engaged, directly or indirectly, in the ownership and management of 231 apartment properties with 12,331 units. We are involved with those VIEs as an equity holder, lender, management agent, or through other contractual relationships. Approximately $22.5 million of our investment in unconsolidated VIEs at March 31, 2012, are held through consolidated partnerships that are VIEs and in which we generally hold a 1% or less general partner or equivalent interest. Accordingly, substantially all of the investment balances related to these unconsolidated VIEs are attributed to the noncontrolling interests in the consolidated investment partnerships that hold the investments in these unconsolidated VIEs. Our maximum risk of loss related to our investment in these VIEs is generally limited to our equity interest in the consolidated investment partnerships, which is insignificant. The remainder of our investment in unconsolidated VIEs, or approximately $5.2 million at March 31, 2012, is held through consolidated investment partnerships that are VIEs and in which we hold substantially all of the economic interests. Our maximum risk of loss related to our investment in these VIEs is limited to our $5.2 million recorded investment in such entities.

As discussed in Note 1, we have entered into an agreement to sell our interests in a portfolio of properties upon satisfaction of certain conditions and regulatory approvals. As of March 31, 2012, this portfolio included 42 consolidated VIEs that owned 18 properties and 130 unconsolidated VIEs that owned 130 properties.

In addition to our investments in unconsolidated VIEs discussed above, at March 31, 2012, we had in aggregate $96.9 million of receivables from unconsolidated VIEs (primarily notes receivable collateralized by second mortgages on real estate properties as further discussed in Note 10) and we had a contractual obligation to advance funds to certain unconsolidated VIEs totaling $3.0 million. Our maximum risk of loss associated with our lending and management activities related to these unconsolidated VIEs is limited to these amounts. We may be subject to additional losses to the extent of any receivables relating to future provision of services to these entities or financial support that we voluntarily provide.

As discussed in Note 8, noncompliance with applicable requirements related to our consolidated and unconsolidated tax credit partnerships, substantially all of which are VIEs, could result in projected tax credits not being realized and require a refund of investor contributions already received or a reduction of future investor contributions. We have not historically had, nor do we anticipate, any material refunds or reductions of investor capital contributions in connection with these arrangements.