Variable Interest Entities	9 Months Ended
Sep. 30, 2011
Basis of Presentation and Summary of Significant Accounting Policies [Abstract]
Variable Interest Entities	NOTE 5 — Variable Interest Entities As of September 30, 2011, we were the primary beneficiary of, and therefore consolidated, approximately 124 VIEs, which owned 84 apartment properties with 12,982 units. Real estate with a carrying value of $805.4 million collateralized $641.8 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 September 30, 2011, we also held variable interests in 215 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 268 apartment properties with 15,818 units. We are involved with those VIEs as an equity holder, lender, management agent, or through other contractual relationships. The majority of our investments in unconsolidated VIEs, or approximately $33.4 million at September 30, 2011, are held through consolidated investment 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 $5.6 million at September 30, 2011, is held through consolidated tax credit funds 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 $5.6 million recorded investment in such entities. In addition to our investments in unconsolidated VIEs discussed above, at September 30, 2011, we had in aggregate $99.7 million of receivables from these unconsolidated VIEs and we had a contractual obligation to advance funds to certain unconsolidated VIEs totaling $3.2 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.

NOTE 5 — Variable Interest Entities

As of September 30, 2011, we were the primary beneficiary of, and therefore consolidated, approximately 124 VIEs, which owned 84 apartment properties with 12,982 units. Real estate with a carrying value of $805.4 million collateralized $641.8 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 September 30, 2011, we also held variable interests in 215 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 268 apartment properties with 15,818 units. We are involved with those VIEs as an equity holder, lender, management agent, or through other contractual relationships. The majority of our investments in unconsolidated VIEs, or approximately $33.4 million at September 30, 2011, are held through consolidated investment 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 $5.6 million at September 30, 2011, is held through consolidated tax credit funds 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 $5.6 million recorded investment in such entities.

In addition to our investments in unconsolidated VIEs discussed above, at September 30, 2011, we had in aggregate $99.7 million of receivables from these unconsolidated VIEs and we had a contractual obligation to advance funds to certain unconsolidated VIEs totaling $3.2 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.