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Unsecured Debt - Narrative (Details) | 1 Months Ended | 3 Months Ended | 12 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Jan. 31, 2017 extension | Nov. 30, 2016 USD ($) | Apr. 30, 2013 USD ($) | Sep. 30, 2012 USD ($) | Dec. 31, 2016 USD ($) line_of_credit instrument | Dec. 31, 2015 USD ($) | Nov. 01, 2016 USD ($) | Apr. 30, 2016 | Mar. 31, 2015 USD ($) | Apr. 01, 2014 USD ($)
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Unamortized debt issuance expense |  |  |  |  | $ 7,400,000 | $ 8,000,000 |  |  |  |
Number of outstanding lines of credit | line_of_credit |  |  |  |  | 2 |  |  |  |  |
Debt instrument, face amount |  |  |  |  | $ 2,850,000,000 | $ 2,400,000,000 |  |  |  |
Effective interest rate |  |  |  |  | 4.50% | 4.50% |  |  |  |
Unsecured debt, net |  |  |  |  | $ 3,246,779,000 | $ 3,088,680,000 |  |  |  |
Senior notes |  |  |  |  | 315,000,000 | 465,000,000 |  |  |  |
Lines of credit |  |  |  |  | 125,000,000 | 15,000,000 |  |  |  |
Swap [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Derivative, notional amount |  | $ 200,000,000.0 |  |  | 25,000,000.0 |  |  |  |  |
Unsecured Line of Credit [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Lines of credit |  |  |  |  | 125,000,000 |  |  |  |  |
Unsecured Bonds 3.375%, Due April 2026 [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  | 450,000,000 | 0 |  |  |  |
Unsecured Bonds 5.500% [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  | 300,000,000 | 300,000,000 |  |  |  |
Unsecured Bonds 5.200% [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  | 300,000,000 | 300,000,000 |  |  |  |
Unsecured Bonds 3.375% [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  | 300,000,000 | 300,000,000 |  |  |  |
Unsecured Bonds 3.875% [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  | 400,000,000 | 400,000,000 |  |  |  |
Unsecured Bonds 3.25% [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  | 300,000,000 | 300,000,000 |  |  |  |
Unsecured Bonds 3.625% [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  | 300,000,000 | 300,000,000 |  |  |  |
Unsecured Debt [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt instrument, unamortized premium |  |  |  |  | (100,000) | 14,300,000 |  |  |  |
Unamortized debt issuance expense |  |  |  |  | 18,100,000 | 15,600,000 |  |  |  |
Unsecured Debt [Member] | Senior Unsecured Notes Maturing April 1, 2025 [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  |  |  |  |  | $ 500,000,000.0 |
Interest rate, stated percentage |  |  |  |  |  |  |  |  | 3.50% |
Debt offering price |  |  |  |  |  |  |  |  | 99.747% |
Senior notes |  |  |  |  | 495,400,000 | 494,800,000 |  |  |  |
Line of Credit [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Maximum borrowing capacity |  |  |  |  | 1,030,000,000 |  |  |  |  |
Line of Credit [Member] | Unsecured Line of Credit [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Unamortized debt issuance expense |  |  |  |  | 3,300,000 | 3,300,000 |  |  |  |
Lines of credit |  |  |  |  | 125,000,000 | 15,000,000 |  |  |  |
Maximum borrowing capacity, accordion option |  |  |  |  | $ 1,000,000,000 |  |  |  |  |
Line of Credit [Member] | Unsecured Line of Credit [Member] | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Line of credit facility Number of one year extensions available | extension | 1 |  |  |  |  |  |  |  |  |
Period for extension option on line of credit | 18 months |  |  |  |  |  |  |  |  |
Line of Credit [Member] | Unsecured Line of Credit [Member] | London Interbank Offered Rate (LIBOR) [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Basis spread on rate (in hundredths) |  |  |  |  | 0.90% |  |  |  |  |
Line of Credit [Member] | Line of Credit Working Capital [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Lines of credit |  |  |  |  | $ 0 |  |  |  |  |
Maximum borrowing capacity, accordion option |  |  |  |  | $ 25,000,000.0 | 0 |  |  |  |
Line of Credit [Member] | Line of Credit Working Capital [Member] | London Interbank Offered Rate (LIBOR) [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Basis spread on rate (in hundredths) |  |  |  |  | 0.90% |  |  |  |  |
Unsecured bonds, private placement [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  | $ 315,000,000.0 | 465,000,000.0 |  |  |  |
Unsecured debt, net |  |  |  |  | $ 314,190,000 | 463,891,000 |  |  |  |
Variable rate term loan [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  | 350,000,000 |  |  |  |  | $ 225,000,000 |  |  |
Basis spread on rate (in hundredths) |  |  |  |  | 0.95% |  |  |  |  |
Unsecured debt, net |  | 350,000,000 |  |  | $ 100,000,000 | $ 225,000,000 |  |  |  |
Weighted average interest rate |  |  |  |  | 2.30% | 2.40% |  |  |  |
Term of loan |  |  |  |  |  | 5 years |  |  |  |
Derivative, notional amount |  | $ 200,000,000.0 |  |  |  | $ 225,000,000 |  |  |  |
Variable rate term loan [Member] | Interest Rate Swap [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Unsecured debt, net |  |  |  |  | $ 100,000,000 |  |  |  |  |
Number of derivative instruments held | instrument |  |  |  |  | 4 |  |  |  |  |
Term of loan |  |  |  |  | 5 years |  |  |  |  |
Variable rate term loan [Member] | Carrying Value [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Unsecured debt, net |  |  |  |  | $ 98,189,000 | $ 224,467,000 |  |  |  |
Variable rate term loan [Member] | London Interbank Offered Rate (LIBOR) [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Basis spread on rate (in hundredths) |  | 0.95% |  |  |  | 1.05% |  |  |  |
Variable rate term loan [Member] | Variable Term Loan, Tranche One [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  |  | $ 200,000,000 |  |  |  |
Variable rate term loan [Member] | Variable Term Loan, Tranche One [Member] | Interest Rate Swap [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Derivative, notional amount |  |  |  |  | $ 150,000,000 |  |  |  |  |
Derivative, Fixed Interest Rate |  |  |  |  | 2.20% |  |  |  |  |
Variable rate term loan [Member] | Variable Term Loan, Tranche Two [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  |  | 25,000,000 |  |  |  |
Variable rate term loan [Member] | Variable Term Loan, Tranche Two [Member] | Interest Rate Swap [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Derivative, notional amount |  |  |  |  | $ 25,000,000 |  |  |  |  |
Derivative, Fixed Interest Rate |  |  |  |  | 2.40% |  |  |  |  |
Senior Notes [Member] | BRE Properties, Inc. [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Unsecured debt, net |  |  |  |  | $ 907,100,000 | 919,100,000 |  |  |  |
Long-term debt acquired |  |  |  |  |  |  |  |  |  | $ 900,000,000
Senior Notes [Member] | Unsecured Bonds 3.375%, Due April 2026 [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Unsecured debt, net |  |  |  |  | $ 443,700,000 |  |  |  |  |
Interest rate, stated percentage |  |  |  |  | 3.375% |  |  |  |  |
Debt offering price |  |  |  |  |  |  |  | 99.386% |  |
Senior Notes [Member] | Unsecured Bonds 5.500% [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Interest rate, stated percentage |  |  |  |  | 5.50% |  |  |  |  |
Senior Notes [Member] | Unsecured Bonds 5.200% [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Interest rate, stated percentage |  |  |  |  | 5.20% |  |  |  |  |
Senior Notes [Member] | Unsecured Bonds 3.375% [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Interest rate, stated percentage |  |  |  |  | 3.375% |  |  |  |  |
Senior Notes [Member] | Unsecured Bonds 3.875% [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  |  |  |  |  |  | $ 400,000,000.0
Unsecured debt, net |  |  |  |  | $ 395,100,000 | 394,500,000 |  |  |  |
Interest rate, stated percentage |  |  |  |  | 3.875% |  |  |  |  | 3.875%
Debt offering price |  |  |  |  |  |  |  |  |  | 99.234%
Senior Notes [Member] | Unsecured Bonds 3.25% [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Interest rate, stated percentage |  |  | 3.25% |  | 3.25% |  |  |  |  |
Debt offering price |  |  | 99.152% |  |  |  |  |  |  |
Proceeds from issuance of unsecured debt |  |  | $ 300,000,000.0 |  |  |  |  |  |  |
Long-term debt, gross |  |  |  |  | $ 296,500,000 | 295,900,000 |  |  |  |
Senior Notes [Member] | Unsecured Bonds 3.625% [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Interest rate, stated percentage |  |  |  | 3.625% | 3.625% |  |  |  |  |
Debt offering price |  |  |  | 98.99% |  |  |  |  |  |
Proceeds from issuance of unsecured debt |  |  |  | $ 300,000,000.0 |  |  |  |  |  |
Long-term debt, gross |  |  |  |  | $ 296,600,000 | $ 296,000,000 |  |  |  |

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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 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 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 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 + Details
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- Definition Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility. + 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 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Weighted average interest rate of long-term debt outstanding. + References No definition available. + Details
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- Definition The cash inflow from the issuance of long-term debt that is not secured by collateral. Excludes proceeds from tax exempt unsecured debt. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Financing Activities -URI http://asc.fasb.org/extlink&oid=6513228 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3255-108585 + Details
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