Derivative and Other Fair Value Instruments (Details 5) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Fair Value, Measurements, Recurring [Member]
Assets, Fair Value Disclosure [Abstract]
Derivatives	$ 13,823	$ 15,797
Supplemental Executive Retirement Plan	57,776	58,132
Available for sale securities	1,687	1,194
Total	73,286	75,123
Liabilities, Fair Value Disclosure [Abstract]
Derivatives	(65,519)	(39,078)
Supplemental Executive Retirement Plan	57,776	58,132
Total	123,295	97,210
Redeemable Noncontrolling interest - operating partnership/redeemable limited partners	438,141	383,540
Fair Value, Measurements, Recurring [Member] \| Quoted Priced in Active Markets for Identical Assets (Level 1)
Assets, Fair Value Disclosure [Abstract]
Derivatives	0	0
Liabilities, Fair Value Disclosure [Abstract]
Derivatives	0	0
Redeemable Noncontrolling interest - operating partnership/redeemable limited partners	0	0
Fair Value, Measurements, Recurring [Member] \| Significant Other Observable Inputs (Level 2)
Assets, Fair Value Disclosure [Abstract]
Available for sale securities	0
Total	13,823
Fair Value, Measurements, Recurring [Member] \| Significant Unobservable Inputs (Level 3)
Assets, Fair Value Disclosure [Abstract]
Derivatives	0	0
Supplemental Executive Retirement Plan	0	0
Available for sale securities	0	0
Total	0	0
Liabilities, Fair Value Disclosure [Abstract]
Derivatives	0	0
Supplemental Executive Retirement Plan	0	0
Total	0	0
Redeemable Noncontrolling interest - operating partnership/redeemable limited partners	0	0
Quoted Priced in Active Markets for Identical Assets (Level 1)
Assets, Fair Value Disclosure [Abstract]
Supplemental Executive Retirement Plan	57,776	58,132
Available for sale securities	1,687	1,194
Total	59,463	59,326
Liabilities, Fair Value Disclosure [Abstract]
Supplemental Executive Retirement Plan	57,776	58,132
Total	57,776	58,132
Significant Other Observable Inputs (Level 2)
Assets, Fair Value Disclosure [Abstract]
Derivatives	13,823	15,797
Supplemental Executive Retirement Plan	0	0
Available for sale securities		0
Total		15,797
Liabilities, Fair Value Disclosure [Abstract]
Derivatives	(65,519)	(39,078)
Supplemental Executive Retirement Plan	0	0
Total	65,519	39,078
Redeemable Noncontrolling interest - operating partnership/redeemable limited partners	$ 438,141	$ 383,540

Fair value as of the balance sheet date of non-controlling interests which are redeemable by the parent at a fixed or determinable price on a fixed or determinable date, at the option of the holder of the non-controlling interest, or upon occurrence of an event that is not solely within the control of the parent.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

This element represents the aggregate of the assets reported on the balance sheet at period end measured at fair value by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

+ Details

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Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Details

Name:	us-gaap_AssetsFairValueDisclosureAbstract
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Balance Type:	na
Period Type:	duration

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 12
-Subparagraph b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6379932&loc=d3e22054-111558

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Available-for-Sale Securities
-URI http://asc.fasb.org/extlink&oid=6505594

+ Details

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Period Type:	instant

- Definition

Fair values as of the balance sheet date of all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements.

+ References

Reference 1: 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=6947722&loc=d3e13495-108611

Reference 2: 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 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FIN39-1
-Paragraph 10A, 10B
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: 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

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 4, 17
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: 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=6947722&loc=d3e13433-108611

+ Details

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Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair values as of the balance sheet date of all liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements.

+ References

+ Details

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Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

This element represents the aggregate of the liabilities reported on the balance sheet at period end measured at fair value by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

+ Details

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Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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Namespace Prefix:	us-gaap
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Balance Type:	credit
Period Type:	instant