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The number of award types for the equity-based compensation plan.

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This element represents the income or loss from continuing operations attributable to noncontrolling interests, if any, which may also be defined as revenue less expenses and taxes from ongoing operations before extraordinary items which are apportioned to that ownership interest in subsidiary equity which is not attributable to the parent.

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This element represents the overall income (loss) from a disposal group that is classified as a component of the entity, net of income tax, reported as a separate component of income before extraordinary items before deduction or consideration of the amount which may be allocable to noncontrolling interests, if any. Includes the following (net of tax): income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

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Fair value as of the balance sheet date of all interest rate derivative liabilities designated as cash flow hedging instruments.

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Carrying amount as of the balance sheet date of investments in land and buildings held for sale, excluding real estate considered to be inventory of the entity.

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Basis of presentation (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2011 property squarefeet form project	Sep. 30, 2010	Sep. 30, 2011 property squarefeet quarter form project	Sep. 30, 2010	Dec. 31, 2010
Income (loss) from continuing and discontinued operations attributable to Alexandria Real Estate Equities, Inc.
Income from continuing operations	$ 33,855	$ 29,982	$ 100,343	$ 45,026
Less: net income attributable to noncontrolling interests	(966)	(920)	(2,833)	(2,785)
Add: gain on sale of land parcel	46		46
Income from continuing operations attributable to Alexandria Real Estate Equities, Inc.	32,935	29,062	97,556	42,241
(Loss) Income from discontinued operations, net	(906)	479	(458)	1,996
(Loss) income from discontinued operations attributable to Alexandria Real Estate Equities, Inc.	(906)	479	(458)	1,996
Number of forms of stock-based compensation under the equity incentive plan	2		2
Assets:
"Available for sale" securities	5,080		5,080		8,033
Number of assets held for sale	1		1
Liabilities:
Interest rate hedge agreements	36,709		36,709		44,645
Fair value measured on recurring basis \| Fair Value
Assets:
"Available for sale" securities	5,080		5,080		8,033
Liabilities:
Interest rate hedge agreements	36,709		36,709		44,645
Fair value measured on recurring basis \| Quoted Prices in Active Markets for Identical Assets and Liabilities
Assets:
"Available for sale" securities	5,080		5,080		8,033
Fair value measured on recurring basis \| "Significant Other Observable Inputs"
Liabilities:
Interest rate hedge agreements	36,709		36,709		44,645
Fair value measured on nonrecurring basis \| Fair Value
Assets:
Properties held for sale	2,900		2,900
Fair value measured on nonrecurring basis \| "Significant Other Observable Inputs"
Assets:
Properties held for sale	$ 2,900		$ 2,900