Condensed consolidating financial information (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Revenues:
Rental	$ 108,367	$ 102,353	$ 318,247	$ 309,532
Tenant recoveries	34,448	33,226	99,006	95,270
Other income (loss)	2,640	2,475	14,650	4,178
Total revenues	145,455	138,054	431,903	408,980
Expenses:
Rental operations	44,614	40,859	127,884	118,014
General and administrative	12,485	10,289	35,152	30,528
Interest	17,094	14,273	51,243	48,621
Depreciation and amortization	47,176	38,747	140,778	113,326
Total expenses	121,369	104,168	355,057	310,489
(Loss) income from continuing operations before equity in earnings of affiliates and loss on early extinguishment of debt	24,086	33,886	76,846	98,491
Loss on early extinguishment of debt		(2,742)	(2,225)	(6,485)
Income from continuing operations	24,086	31,144	74,621	92,006
(Loss) income from discontinued operations:
Income from discontinued operations before impairment of real estate	4,018	2,799	10,035	8,873
Impairment of real estate	(9,799)	(994)	(9,799)	(994)
(Loss) income from discontinued operations, net	(5,781)	1,805	236	7,879
Gain on sale of land parcel		46	1,864	46
Net income	18,305	32,995	76,721	99,931
Net income attributable to noncontrolling interests	828	966	2,390	2,833
Dividends on preferred stock	6,471	7,089	20,857	21,267
Preferred stock redemption charge			5,978
Net income attributable to unvested restricted stock awards	360	278	866	818
Net income attributable to Alexandria Real Estate Equities, Inc.'s common stockholders	10,646	24,662	46,630	75,013
Alexandria Real Estate Equities, Inc. (Issuer)
Revenues:
Other income (loss)	2,091	2,032	5,199	6,542
Total revenues	2,091	2,032	5,199	6,542
Expenses:
General and administrative	9,585	9,423	32,030	26,977
Interest	11,786	11,967	34,460	32,727
Depreciation and amortization	1,726	937	3,781	2,427
Total expenses	23,097	22,327	70,271	62,131
(Loss) income from continuing operations before equity in earnings of affiliates and loss on early extinguishment of debt	(21,006)	(20,295)	(65,072)	(55,589)
Equity in earnings of affiliates	42,074	53,876	142,660	155,514
Loss on early extinguishment of debt		(2,742)	(2,225)	(6,485)
Income from continuing operations	21,068	30,839	75,363	93,440
(Loss) income from discontinued operations:
Income from discontinued operations before impairment of real estate	1,208	1,190	3,767	3,658
Impairment of real estate	4,799		4,799
(Loss) income from discontinued operations, net	(3,591)	1,190	(1,032)	3,658
Net income	17,477	32,029	74,331	97,098
Dividends on preferred stock	6,471	7,089	20,857	21,267
Preferred stock redemption charge			5,978
Net income attributable to unvested restricted stock awards	360	278	866	818
Net income attributable to Alexandria Real Estate Equities, Inc.'s common stockholders	10,646	24,662	46,630	75,013
Alexandria Real Estate Equities, L.P. (Guarantor Subsidiary)
Revenues:
Other income (loss)	51	(200)	891	(515)
Total revenues	51	(200)	891	(515)
Expenses:
General and administrative		7		7
Total expenses		7		7
(Loss) income from continuing operations before equity in earnings of affiliates and loss on early extinguishment of debt	51	(207)	891	(522)
Equity in earnings of affiliates	41,874	50,873	134,347	146,803
Income from continuing operations	41,925	50,666	135,238	146,281
(Loss) income from discontinued operations:
Net income	41,925	50,666	135,238	146,281
Net income attributable to Alexandria Real Estate Equities, Inc.'s common stockholders	41,925	50,666	135,238	146,281
Non-Guarantor Subsidiaries
Revenues:
Rental	108,367	102,353	318,247	309,532
Tenant recoveries	34,448	33,226	99,006	95,270
Other income (loss)	3,915	3,982	18,500	7,967
Total revenues	146,730	139,561	435,753	412,769
Expenses:
Rental operations	44,614	40,859	127,884	118,014
General and administrative	6,317	4,198	13,062	13,360
Interest	5,308	2,306	16,783	15,894
Depreciation and amortization	45,450	37,810	136,997	110,899
Total expenses	101,689	85,173	294,726	258,167
(Loss) income from continuing operations before equity in earnings of affiliates and loss on early extinguishment of debt	45,041	54,388	141,027	154,602
Equity in earnings of affiliates	781	973	2,662	2,896
Income from continuing operations	45,822	55,361	143,689	157,498
(Loss) income from discontinued operations:
Income from discontinued operations before impairment of real estate	2,810	1,609	6,268	5,215
Impairment of real estate	5,000	994	5,000	(994)
(Loss) income from discontinued operations, net	(2,190)	615	1,268	4,221
Gain on sale of land parcel		46	1,864	46
Net income	43,632	56,022	146,821	161,765
Net income attributable to noncontrolling interests	828	966	2,390	2,833
Net income attributable to Alexandria Real Estate Equities, Inc.'s common stockholders	42,804	55,056	144,431	158,932
Eliminations
Revenues:
Other income (loss)	(3,417)	(3,339)	(9,940)	(9,816)
Total revenues	(3,417)	(3,339)	(9,940)	(9,816)
Expenses:
General and administrative	(3,417)	(3,339)	(9,940)	(9,816)
Total expenses	(3,417)	(3,339)	(9,940)	(9,816)
Equity in earnings of affiliates	(84,729)	(105,722)	(279,669)	(305,213)
Income from continuing operations	(84,729)	(105,722)	(279,669)	(305,213)
(Loss) income from discontinued operations:
Net income	(84,729)	(105,722)	(279,669)	(305,213)
Net income attributable to Alexandria Real Estate Equities, Inc.'s common stockholders	$ (84,729)	$ (105,722)	$ (279,669)	$ (305,213)