Condensed consolidating financial information (Details 4) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Operating Activities
Net income	$ 18,305	$ 32,995	$ 76,721	$ 99,931
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization			143,933	117,060
Loss on early extinguishment of debt		2,742	2,225	6,485
Gain on sale of land parcel		(46)	(1,864)	(46)
Gain on sale of real estate	(1,562)		(1,564)
Non-cash impairment of real estate	9,799	994	9,799	994
Amortization of loan fees and costs			7,327	6,749
Amortization of debt premiums/discounts			401	3,254
Amortization of acquired above and below market leases			(2,356)	(8,520)
Deferred rent			(19,216)	(17,239)
Stock compensation expense			10,412	8,449
Equity in income (loss) related to investments			26
Gain on sales of investments			(12,316)	(3,555)
Loss on sales of investments			1,607	1,240
Changes in operating assets and liabilities:
Restricted cash			441	489
Tenant receivables			(2,637)	(1,328)
Deferred leasing costs			(23,597)	(51,581)
Other assets			(3,230)	(8,735)
Accounts payable, accrued expenses, and tenant security deposits			41,378	26,325
Net cash provided by operating activities			227,490	179,972
Investing Activities
Proceeds from sale of property			36,179	17,339
Distributions from unconsolidated real estate entity related to sale of land parcel			22,250
Additions to properties			(406,066)	(293,688)
Purchase of properties			(42,171)	(307,839)
Change in restricted cash related to construction projects			(11,453)	(2,891)
Contributions to unconsolidated real estate entity			(5,042)	(3,256)
Additions to investments			(21,997)	(19,663)
Proceeds from investments			19,905	14,496
Net cash used in investing activities			(408,395)	(595,502)
Financing Activities
Principal borrowings from secured notes payable			2,874
Repayments of borrowings from secured notes payable			(8,125)	(30,181)
Proceeds from issuance of unsecured senior notes payable			544,649
Repurchase of unsecured senior convertible notes			(84,801)	(221,439)
Principal borrowings from unsecured senior line of credit and unsecured senior bank term loans			623,147	1,990,317
Repayments of borrowings from unsecured senior line of credit			(580,147)	(1,174,317)
Repayment of unsecured senior bank term loan			(250,000)	(500,000)
Redemption of Series C Preferred Stock			129,638
Proceeds from issuance of Series E Preferred Stock			124,868
Proceeds from issuance of common stock			98,443	451,539
Change in restricted cash related to financings			(10,476)	2,591
Deferred financing costs paid			(20,417)	(20,268)
Proceeds from exercise of stock options			155	1,165
Dividends paid on common stock			(92,743)	(77,787)
Dividends paid on preferred stock			(21,348)	(21,268)
Distributions to redeemable noncontrolling interests			(943)	(939)
Redemption of redeemable noncontrolling interests			(150)
Contributions by noncontrolling interests			1,626
Distributions to noncontrolling interests			(770)	(2,084)
Net cash provided by financing activities			196,204	397,329
Effect of exchange rate changes on cash and cash equivalents			1,066	25
Net increase (decrease) in cash and cash equivalents			16,365	(18,176)
Cash and cash equivalents at beginning of period			78,539	91,232
Cash and cash equivalents at end of period	94,904	73,056	94,904	73,056
Supplemental Disclosure of Cash Flow Information
Cash paid during the period for interest, net of interest capitalized			30,952	38,013
Non-Cash Investing Activities
Note receivable from sale of real estate			(6,125)
Alexandria Real Estate Equities, Inc. (Issuer)
Operating Activities
Net income	17,477	32,029	74,331	97,098
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization			3,781	2,427
Loss on early extinguishment of debt		2,742	2,225	6,485
Non-cash impairment of real estate	(4,799)		(4,799)
Amortization of loan fees and costs			5,307	5,134
Amortization of debt premiums/discounts			104	3,060
Deferred rent			164
Stock compensation expense			10,412	8,449
Equity in income related to subsidiaries	(42,074)	(53,876)	(142,660)	(155,514)
Changes in operating assets and liabilities:
Restricted cash			(8)	18
Tenant receivables			11	(2)
Deferred leasing costs			4,232	1,387
Other assets			2,603	2,071
Intercompany receivables and payables			(49)	(1,418)
Accounts payable, accrued expenses, and tenant security deposits			3,592	(13,361)
Net cash provided by operating activities			(31,156)	(44,166)
Investing Activities
Additions to properties			(1,192)	(844)
Investments in subsidiaries			(145,389)	(415,486)
Net cash used in investing activities			(146,581)	(416,330)
Financing Activities
Proceeds from issuance of unsecured senior notes payable			544,649
Repurchase of unsecured senior convertible notes			(84,801)	(221,439)
Principal borrowings from unsecured senior line of credit and unsecured senior bank term loans			623,147	1,990,317
Repayments of borrowings from unsecured senior line of credit			(580,147)	(1,674,317)
Repayment of unsecured senior bank term loan			(250,000)
Redemption of Series C Preferred Stock			(129,638)
Proceeds from issuance of Series E Preferred Stock			124,868
Proceeds from issuance of common stock			98,443	451,539
Deferred financing costs paid			(15,065)	(20,124)
Proceeds from exercise of stock options			155	1,165
Dividends paid on common stock			(92,743)	(77,787)
Dividends paid on preferred stock			(21,348)	(21,268)
Redemption of redeemable noncontrolling interests			4
Net cash provided by financing activities			217,524	428,086
Net increase (decrease) in cash and cash equivalents			39,787	(32,410)
Cash and cash equivalents at beginning of period			10,608	48,623
Cash and cash equivalents at end of period	50,395	16,213	50,395	16,213
Supplemental Disclosure of Cash Flow Information
Cash paid during the period for interest, net of interest capitalized			23,693	24,296
Alexandria Real Estate Equities, L.P. (Guarantor Subsidiary)
Operating Activities
Net income	41,925	50,666	135,238	146,281
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in income (loss) related to investments			26
Equity in income related to subsidiaries	(41,874)	(50,873)	(134,347)	(146,803)
Gain on sales of investments			(1,109)	(236)
Loss on sales of investments			195	767
Changes in operating assets and liabilities:
Net cash provided by operating activities			3	9
Investing Activities
Investments in subsidiaries			(112,504)	(396,720)
Additions to investments			(160)	(314)
Proceeds from investments			1,944	2,059
Net cash used in investing activities			(110,720)	(394,975)
Financing Activities
Transfers due to/from parent company			110,717	394,474
Net cash provided by financing activities			110,717	394,474
Net increase (decrease) in cash and cash equivalents				(492)
Cash and cash equivalents at beginning of period				602
Cash and cash equivalents at end of period		110		110
Non-Guarantor Subsidiaries
Operating Activities
Net income	43,632	56,022	146,821	161,765
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization			140,152	114,633
Gain on sale of land parcel		(46)	(1,864)	(46)
Gain on sale of real estate			(1,564)
Non-cash impairment of real estate	(5,000)	(994)	(5,000)	994
Amortization of loan fees and costs			2,020	1,615
Amortization of debt premiums/discounts			297	194
Amortization of acquired above and below market leases			(2,356)	(8,520)
Deferred rent			(19,380)	(17,239)
Equity in income related to subsidiaries	(781)	(973)	(2,662)	(2,896)
Gain on sales of investments			(11,207)	(3,319)
Loss on sales of investments			1,412	473
Changes in operating assets and liabilities:
Restricted cash			449	471
Tenant receivables			(2,648)	(1,326)
Deferred leasing costs			(27,829)	(52,968)
Other assets			(5,833)	(10,806)
Intercompany receivables and payables			49	1,418
Accounts payable, accrued expenses, and tenant security deposits			37,786	39,686
Net cash provided by operating activities			258,643	224,129
Investing Activities
Proceeds from sale of property			36,179	17,339
Distributions from unconsolidated real estate entity related to sale of land parcel			22,250
Additions to properties			(404,874)	(292,844)
Purchase of properties			(42,171)	(307,839)
Change in restricted cash related to construction projects			(11,453)	(2,891)
Contributions to unconsolidated real estate entity			(5,042)	(3,256)
Investments in subsidiaries			(389)	(10,093)
Additions to investments			(21,837)	(19,349)
Proceeds from investments			17,961	12,437
Net cash used in investing activities			(409,376)	(606,496)
Financing Activities
Principal borrowings from secured notes payable			2,874
Repayments of borrowings from secured notes payable			(8,125)	(30,181)
Transfers due to/from parent company			147,565	427,825
Change in restricted cash related to financings			(10,476)	2,591
Deferred financing costs paid			(5,352)	(144)
Distributions to redeemable noncontrolling interests			(943)	(939)
Redemption of redeemable noncontrolling interests			(154)
Contributions by noncontrolling interests			1,626
Distributions to noncontrolling interests			(770)	(2,084)
Net cash provided by financing activities			126,245	397,068
Effect of exchange rate changes on cash and cash equivalents			1,066	25
Net increase (decrease) in cash and cash equivalents			(23,422)	14,726
Cash and cash equivalents at beginning of period			67,931	42,007
Cash and cash equivalents at end of period	44,509	56,733	44,509	56,733
Supplemental Disclosure of Cash Flow Information
Cash paid during the period for interest, net of interest capitalized			7,259	13,717
Non-Cash Investing Activities
Note receivable from sale of real estate			(6,125)
Eliminations
Operating Activities
Net income	(84,729)	(105,722)	(279,669)	(305,213)
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in income related to subsidiaries	84,729	105,722	279,669	305,213
Investing Activities
Investments in subsidiaries			258,282	822,299
Net cash used in investing activities			258,282	822,299
Financing Activities
Transfers due to/from parent company			(258,282)	(822,299)
Net cash provided by financing activities			$ (258,282)	$ (822,299)