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Fair Value of Derivatives and Financial Instruments (Details) - USD ($) $ in Thousands | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
--- | --- | --- | ---
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financing Receivable, Net | $ 16,694 | $ 14,369 |
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis |  |  |
Derivative Asset | 13 | 88 |
Derivative Liability | 2,112 | 10,368 |
Secured debt instruments - variable rate |  |  |
Long-term Line of Credit | 2,300 | 1,900 |
Unsecured debt instruments |  |  |
Redeemable Noncontrolling Interest, Equity, Carrying Amount | 946,436 | 282,480 |
Redeemable non-controlling interests in the Operating Partnership and DownREIT Partnership | 946,436 | 282,480 | $ 217,597
Carrying Amount | Fair Value, Measurements, Recurring |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Financing Receivable, Net | 16,694 | 14,369 |
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis |  |  |
Total assets | 16,707 | 14,457 |
Unsecured debt instruments |  |  |
Total liabilities | 3,590,829 | 3,593,473 |
Carrying Amount | Interest rate contracts | Fair Value, Measurements, Recurring |  |  |
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis |  |  |
Derivative Liability |  | 10,368 |
Carrying Amount | Senior unsecured notes | Fair Value, Measurements, Recurring |  |  |
Unsecured debt instruments |  |  |
Unsecured debt instruments | 2,056,223 | 2,069,076 |
Fair Value | Fair Value, Measurements, Recurring |  |  |
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis |  |  |
Notes receivable | 16,938 | 14,808 |
Total assets | 16,951 | 14,896 |
Unsecured debt instruments |  |  |
Total liabilities | 3,673,283 | 3,721,512 |
Redeemable non-controlling interests in the Operating Partnership and DownREIT Partnership | 946,436 | 282,480 |
Fair Value | Interest rate contracts | Fair Value, Measurements, Recurring |  |  |
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis |  |  |
Derivative Asset Designated as Hedging Instrument, Fair Value | 13 | 88 |
Derivatives - Interest rate contracts | 2,112 | 10,368 |
Fair Value | Mortgages [Member] | Fair Value, Measurements, Recurring |  |  |
Secured debt instruments - fixed rate |  |  |
Secured debt instruments - fixed rate | 448,019 | 415,663 |
Secured debt instruments - variable rate |  |  |
Secured debt instruments - variable rate | 31,337 | 31,337 |
Fair Value | Tax-exempt secured notes payable | Fair Value, Measurements, Recurring |  |  |
Secured debt instruments - variable rate |  |  |
Secured debt instruments - variable rate | 94,700 | 94,700 |
Fair Value | Fannie Mae credit facilities | Fair Value, Measurements, Recurring |  |  |
Secured debt instruments - fixed rate |  |  |
Secured debt instruments - fixed rate | 539,050 | 606,623 |
Secured debt instruments - variable rate |  |  |
Secured debt instruments - variable rate | 299,378 | 266,196 |
Unsecured debt instruments |  |  |
Unsecured debt instruments | 150,000 | 152,500 |
Fair Value | Senior unsecured notes | Fair Value, Measurements, Recurring |  |  |
Unsecured debt instruments |  |  |
Unsecured debt instruments | 2,108,687 | 2,144,125 |
Fair Value | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) | Fair Value, Measurements, Recurring |  |  |
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis |  |  |
Notes receivable | 0 | 0 |
Total assets | 0 | 0 |
Unsecured debt instruments |  |  |
Total liabilities | 0 | 0 |
Redeemable non-controlling interests in the Operating Partnership and DownREIT Partnership | 0 | 0 |
Fair Value | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) | Interest rate contracts | Fair Value, Measurements, Recurring |  |  |
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis |  |  |
Derivative Asset Designated as Hedging Instrument, Fair Value | 0 | 0 |
Derivatives - Interest rate contracts | 0 | 0 |
Fair Value | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) | Mortgages [Member] | Fair Value, Measurements, Recurring |  |  |
Secured debt instruments - fixed rate |  |  |
Secured debt instruments - fixed rate | 0 | 0 |
Secured debt instruments - variable rate |  |  |
Secured debt instruments - variable rate | 0 | 0 |
Fair Value | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) | Tax-exempt secured notes payable | Fair Value, Measurements, Recurring |  |  |
Secured debt instruments - variable rate |  |  |
Secured debt instruments - variable rate | 0 | 0 |
Fair Value | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) | Fannie Mae credit facilities | Fair Value, Measurements, Recurring |  |  |
Secured debt instruments - fixed rate |  |  |
Secured debt instruments - fixed rate | 0 | 0 |
Secured debt instruments - variable rate |  |  |
Secured debt instruments - variable rate | 0 | 0 |
Fair Value | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) | Commercial bank | Fair Value, Measurements, Recurring |  |  |
Unsecured debt instruments |  |  |
Unsecured debt instruments | 0 | 0 |
Fair Value | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) | Senior unsecured notes | Fair Value, Measurements, Recurring |  |  |
Unsecured debt instruments |  |  |
Unsecured debt instruments | 0 | 0 |
Fair Value | Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Recurring |  |  |
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis |  |  |
Notes receivable | 0 | 0 |
Total assets | 13 | 88 |
Unsecured debt instruments |  |  |
Total liabilities | 2,112 | 10,368 |
Redeemable non-controlling interests in the Operating Partnership and DownREIT Partnership | 946,436 | 282,480 |
Fair Value | Significant Other Observable Inputs (Level 2) | Interest rate contracts | Fair Value, Measurements, Recurring |  |  |
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis |  |  |
Derivative Asset Designated as Hedging Instrument, Fair Value | 13 | 88 |
Derivatives - Interest rate contracts | 2,112 | 10,368 |
Fair Value | Significant Other Observable Inputs (Level 2) | Mortgages [Member] | Fair Value, Measurements, Recurring |  |  |
Secured debt instruments - fixed rate |  |  |
Secured debt instruments - fixed rate | 0 | 0 |
Secured debt instruments - variable rate |  |  |
Secured debt instruments - variable rate | 0 | 0 |
Fair Value | Significant Other Observable Inputs (Level 2) | Tax-exempt secured notes payable | Fair Value, Measurements, Recurring |  |  |
Secured debt instruments - variable rate |  |  |
Secured debt instruments - variable rate | 0 | 0 |
Fair Value | Significant Other Observable Inputs (Level 2) | Fannie Mae credit facilities | Fair Value, Measurements, Recurring |  |  |
Secured debt instruments - fixed rate |  |  |
Secured debt instruments - fixed rate | 0 | 0 |
Secured debt instruments - variable rate |  |  |
Secured debt instruments - variable rate | 0 | 0 |
Fair Value | Significant Other Observable Inputs (Level 2) | Commercial bank | Fair Value, Measurements, Recurring |  |  |
Unsecured debt instruments |  |  |
Unsecured debt instruments | 0 | 0 |
Fair Value | Significant Other Observable Inputs (Level 2) | Senior unsecured notes | Fair Value, Measurements, Recurring |  |  |
Unsecured debt instruments |  |  |
Unsecured debt instruments | 0 | 0 |
Fair Value | Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Recurring |  |  |
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis |  |  |
Notes receivable | 16,938 | 14,808 |
Total assets | 16,938 | 14,808 |
Unsecured debt instruments |  |  |
Total liabilities | 3,671,171 | 3,711,144 |
Redeemable non-controlling interests in the Operating Partnership and DownREIT Partnership | 0 | 0 |
Fair Value | Significant Unobservable Inputs (Level 3) | Interest rate contracts | Fair Value, Measurements, Recurring |  |  |
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis |  |  |
Derivative Asset Designated as Hedging Instrument, Fair Value | 0 | 0 |
Derivatives - Interest rate contracts | 0 | 0 |
Fair Value | Significant Unobservable Inputs (Level 3) | Mortgages [Member] | Fair Value, Measurements, Recurring |  |  |
Secured debt instruments - fixed rate |  |  |
Secured debt instruments - fixed rate | 448,019 | 415,663 |
Secured debt instruments - variable rate |  |  |
Secured debt instruments - variable rate | 31,337 | 31,337 |
Fair Value | Significant Unobservable Inputs (Level 3) | Tax-exempt secured notes payable | Fair Value, Measurements, Recurring |  |  |
Secured debt instruments - variable rate |  |  |
Secured debt instruments - variable rate | 94,700 | 94,700 |
Fair Value | Significant Unobservable Inputs (Level 3) | Fannie Mae credit facilities | Fair Value, Measurements, Recurring |  |  |
Secured debt instruments - fixed rate |  |  |
Secured debt instruments - fixed rate | 539,050 | 606,623 |
Secured debt instruments - variable rate |  |  |
Secured debt instruments - variable rate | 299,378 | 266,196 |
Fair Value | Significant Unobservable Inputs (Level 3) | Commercial bank | Fair Value, Measurements, Recurring |  |  |
Unsecured debt instruments |  |  |
Unsecured debt instruments | 150,000 | 152,500 |
Fair Value | Significant Unobservable Inputs (Level 3) | Senior unsecured notes | Fair Value, Measurements, Recurring |  |  |
Unsecured debt instruments |  |  |
Unsecured debt instruments | 2,108,687 | 2,144,125 |
Fixed Rate Debt |  |  |
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis |  |  |
Secured Debt Including Debt on Real Estate Held for Sale | 952,801 | 963,713 |
Variable Rate Debt |  |  |
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis |  |  |
Secured Debt Including Debt on Real Estate Held for Sale | 424,144 | 390,608 |
Unsecured Revolving Credit Facility due October 2015 |  |  |
Secured debt instruments - variable rate |  |  |
Long-term Line of Credit | 150,000 | 152,500 |
Tax-exempt secured notes payable | Variable Rate Debt | Carrying Amount | Tax-exempt secured notes payable | Fair Value, Measurements, Recurring |  |  |
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis |  |  |
Secured Debt Including Debt on Real Estate Held for Sale | 94,700 | 94,700 |
Fannie Mae credit facilities | Fixed Rate Debt | Carrying Amount | Fannie Mae credit facilities | Fair Value, Measurements, Recurring |  |  |
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis |  |  |
Secured Debt Including Debt on Real Estate Held for Sale | 514,462 | 568,086 |
Fannie Mae credit facilities | Variable Rate Debt | Carrying Amount | Fannie Mae credit facilities | Fair Value, Measurements, Recurring |  |  |
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis |  |  |
Secured Debt Including Debt on Real Estate Held for Sale | 299,378 | 266,196 |
Mortgages [Member] | Fixed Rate Debt | Carrying Amount | Mortgages [Member] | Fair Value, Measurements, Recurring |  |  |
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis |  |  |
Secured Debt Including Debt on Real Estate Held for Sale | 442,617 | 401,210 |
Mortgages [Member] | Variable Rate Debt | Carrying Amount | Mortgages [Member] | Fair Value, Measurements, Recurring |  |  |
Estimated fair values of the financial instruments either recorded or disclosed on a recurring basis |  |  |
Secured Debt Including Debt on Real Estate Held for Sale | $ 31,337 | $ 31,337 |

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- Definition Fair value, after offset of derivative asset, of financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, elected not to be and before offset against a right to receive collateral under a master netting arrangement. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 8 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=35706170&loc=d3e41678-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=34720828&loc=SL20225862-175312 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 9 -URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226006-175313 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226008-175313 + Details
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- Definition Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226008-175313 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13495-108611 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=34720828&loc=SL20225862-175312 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13433-108611 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958 + Details
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- Definition The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.16) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.16) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 20, 22 -Article 5 + Details
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- Definition Fair value portion of an agreement for an unconditional promise by the maker to pay the holder a definite sum of money at a future date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.3(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 3 -Subparagraph b -Article 5 + Details
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- Definition Net amount of the investment in a contractual right to receive money on demand or on fixed or determinable dates that is recognized as an asset in the creditor's statement of financial position. Examples include, but are not limited to, credit card receivables, notes receivable and receivables relating to lessor's rights to payments from leases other than operating leases that have been recorded as assets. Excludes trade accounts receivable with contractual maturity of one year or less and arose from the sale of goods or services. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.3) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 3 -Article 5 + Details
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