Debt Mortgage Notes Payable (Details) $ in Thousands	6 Months Ended
Jun. 30, 2016 USD ($) property	Dec. 31, 2015 USD ($)
Debt Instrument [Line Items]
Mortgage notes payable	$ 4,147,999	$ 4,685,134
Noncash or Part Noncash Acquisition, Debt Assumed	$ 43,400
Properties acquired \| property	3
Write Off Of Unamortized Deferred Financing Costs	$ 1,900
Write off unamortized premium discount	25,200
Mortgages [Member]
Debt Instrument [Line Items]
Repayments Of Long-term Debt	$ 4,700
Properties acquired \| property	1
Write Off Of Unamortized Deferred Financing Costs	$ 1,400
Write off unamortized premium discount	$ 20,700
Debt Instrument, Maturity Date	May 28, 2061
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum	0.10%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum	7.20%
Weighted Average Mortgage Debt Interest Rate	4.34%
Bonds [Member]
Debt Instrument [Line Items]
Repayments Of Long-term Debt	$ 57,800
Prepayment Penalty Charges	200
Conventional Mortgage Loan [Member]
Debt Instrument [Line Items]
Repayments Of Long-term Debt	57,900
Credit enhanced debt [Member]
Debt Instrument [Line Items]
Mortgage notes payable	610,500
Fannie Mae Pool 3 [Member] \| Mortgages [Member]
Debt Instrument [Line Items]
Repayments Of Long-term Debt	$ 440,800
Debt Instrument, Interest Rate, Stated Percentage	6.256%
Prepayment Penalty Charges	$ 29,300

Represents charges to interest expense related to the extinguishment of borrowing before maturity.

No definition available.

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- Definition

Total number of property or properties acquired from unaffiliated third parties during the period.

+ References

No definition available.

+ Details

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- Definition

The weighted average interest rate on total mortgage debt for the period.

+ References

No definition available.

+ Details

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- Definition

Represents charges to interest expense related to the extinguishment of borrowing before maturity.

+ References

No definition available.

+ Details

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- Definition

The charge to earnings for the amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized in conjunction with early debt extinguishment.

+ References

No definition available.

+ Details

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- Definition

Contractual interest rate for funds borrowed, under the debt 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(a)(1))
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- Definition

Maximum contractual interest rate for funds borrowed, under the debt agreement.

+ References

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- Definition

Minimum contractual interest rate for funds borrowed, under the debt agreement.

+ References

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-Name Accounting Standards Codification
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

The amount of debt that an Entity assumes in acquiring a business or in consideration for an asset received in a noncash (or part noncash) acquisition. Noncash is defined as transactions during a period that affect recognized assets or liabilities but that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

+ References

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- Definition

The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

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- Definition

Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.

+ References

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-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 19, 20, 22
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