Debt - Debt Summary (Details) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Unsecured debt, net	$ 3,093,106	$ 2,603,548
Lines of credit, net	28,762	242,824
Mortgage notes payable, net	2,247,463	2,234,317
Total debt	5,369,331	5,080,689
Fixed Rate Bond One [Member]
Debt Instrument [Line Items]
Unsecured debt, net	$ 463,667	463,443
Debt, weighted average maturity (years)	3 years 8 months 12 days
Loans Payable [Member]
Debt Instrument [Line Items]
Unsecured debt, net	$ 224,299	$ 224,130
Debt, weighted average maturity (years)	1 year 4 months 12 days
Weighted average interest rate	2.40%	2.40%
Fixed Rate Bond Two [Member]
Debt Instrument [Line Items]
Unsecured debt, net	$ 2,405,140	$ 1,915,975
Debt, weighted average maturity (years)	7 years 3 months 12 days
Weighted average interest rate	3.60%	3.60%
Unsecured Line of Credit [Member]
Debt Instrument [Line Items]
Lines of credit, net	$ 28,762	$ 242,824
Weighted average interest rate	1.90%	1.80%
Mortgage Notes [Member]
Debt Instrument [Line Items]
Debt, weighted average maturity (years)	6 years 6 months 12 days
Mortgage notes payable, net	$ 2,247,463	$ 2,234,317
Weighted average interest rate	4.40%	4.60%

The period when the debt instrument is scheduled to be fully repaid.

No definition available.

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- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of uncollateralized debt obligations (with maturities initially due after one year or beyond the operating cycle if longer) and 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

No definition available.

+ Details

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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

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

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- Definition

Weighted average interest rate of long-term debt outstanding.

+ References

No definition available.

+ Details

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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

+ Details

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- Definition

+ References

+ Details

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