Condensed consolidating financial information Income Statement (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended			9 Months Ended
	Dec. 31, 2014	Sep. 30, 2015	Mar. 31, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Revenues:
Rental		$ 155,311		$ 137,718	$ 450,724	$ 403,280
Tenant recoveries		56,119		45,572	154,107	128,198
Other income		7,180		2,325	14,688	6,725
Total revenues		218,610		185,615	619,519	538,203
Expenses:
Rental operations		68,846		57,423	192,319	162,283
General and administrative		15,143		12,609	44,519	39,669
Interest		27,679		20,555	77,583	57,111
Depreciation and amortization		67,953		58,388	189,044	166,123
Impairment of real estate	$ 16,600	0		0	14,510	0
Loss on early extinguishment of debt		0		525	189	525
Total expenses		179,621		149,500	518,164	425,711
Equity in earnings of unconsolidated joint ventures		710		0	1,825	0
Income (Loss) from Subsidiaries, before Tax		0		0	0	0
Income from continuing operations		39,699		36,115	103,180	112,492
(Loss) income from discontinued operations, net		0		(180)	(43)	(489)
Gain on sales of real estate – land parcels		0		8	0	805
Net income		39,699		35,943	103,137	112,808
Dividends on preferred stock		(6,247)		(6,471)	(18,740)	(19,414)
Net income attributable to noncontrolling interests		(170)		(1,340)	(925)	(3,842)
Net income attributable to unvested restricted stock awards		(623)		(506)	(1,736)	(1,285)
Net income attributable to Alexandria’s common stockholders		32,659		27,626	81,736	88,267
Alexandria Real Estate Equities, Inc. (Issuer)
Revenues:
Rental		0		0	0	0
Tenant recoveries		0		0	0	0
Other income		3,355		2,797	9,890	8,632
Total revenues		3,355		2,797	9,890	8,632
Expenses:
Rental operations		0		0	0	0
General and administrative		13,511		11,369	38,960	33,735
Interest		20,470		15,307	57,494	41,339
Depreciation and amortization		1,799		1,408	4,515	4,335
Impairment of real estate					0
Loss on early extinguishment of debt				525	189	525
Total expenses		35,780		28,609	101,158	79,934
Equity in earnings of unconsolidated joint ventures		0			0
Income (Loss) from Subsidiaries, before Tax		71,954		60,415	193,480	180,275
Income from continuing operations				34,603	102,212	108,973
(Loss) income from discontinued operations, net				0	0	(7)
Gain on sales of real estate – land parcels				0		0
Net income		39,529		34,603	102,212	108,966
Dividends on preferred stock		(6,247)		(6,471)	(18,740)	(19,414)
Net income attributable to noncontrolling interests		0		0	0	0
Net income attributable to unvested restricted stock awards		(623)		(506)	(1,736)	(1,285)
Net income attributable to Alexandria’s common stockholders		32,659		27,626	81,736	88,267
Alexandria Real Estate Equities, L.P. (Guarantor Subsidiary)
Revenues:
Rental		0		0	0	0
Tenant recoveries		0		0	0	0
Other income		(87)		(1,264)	(128)	(2,799)
Total revenues		(87)		(1,264)	(128)	(2,799)
Expenses:
Rental operations		0		0	0	0
General and administrative		0		0	0	0
Interest		0		0	0	0
Depreciation and amortization		0		0	0	0
Impairment of real estate					0
Loss on early extinguishment of debt			$ 0	0	0	0
Total expenses		0		0	0	0
Equity in earnings of unconsolidated joint ventures		0			0
Income (Loss) from Subsidiaries, before Tax		63,964		58,381	174,800	172,989
Income from continuing operations				57,117	174,672	170,190
(Loss) income from discontinued operations, net				0	0	0
Gain on sales of real estate – land parcels				0		0
Net income		63,877		57,117	174,672	170,190
Dividends on preferred stock		0		0	0	0
Net income attributable to noncontrolling interests		0		0	0	0
Net income attributable to unvested restricted stock awards		0		0	0	0
Net income attributable to Alexandria’s common stockholders		63,877		57,117	174,672	170,190
Combined Non- Guarantor Subsidiaries
Revenues:
Rental		155,311		137,718	450,724	403,280
Tenant recoveries		56,119		45,572	154,107	128,198
Other income		8,025		4,369	17,014	11,534
Total revenues		219,455		187,659	621,845	543,012
Expenses:
Rental operations		68,846		57,423	192,319	162,283
General and administrative		5,745		4,817	17,647	16,576
Interest		7,209		5,248	20,089	15,772
Depreciation and amortization		66,154		56,980	184,529	161,788
Impairment of real estate					14,510
Loss on early extinguishment of debt			$ 0	0	0	0
Total expenses		147,954		124,468	429,094	356,419
Equity in earnings of unconsolidated joint ventures		710			1,825
Income (Loss) from Subsidiaries, before Tax		1,259		1,127	3,446	3,356
Income from continuing operations				64,318	198,022	189,949
(Loss) income from discontinued operations, net				(180)	(43)	(482)
Gain on sales of real estate – land parcels				8		805
Net income		73,470		64,146	197,979	190,272
Dividends on preferred stock		0		0	0	0
Net income attributable to noncontrolling interests		(170)		(1,340)	(925)	(3,842)
Net income attributable to unvested restricted stock awards		0		0	0	0
Net income attributable to Alexandria’s common stockholders		73,300		62,806	197,054	186,430
Eliminations
Revenues:
Rental		0		0	0	0
Tenant recoveries		0		0	0	0
Other income		(4,113)		(3,577)	(12,088)	(10,642)
Total revenues		(4,113)		(3,577)	(12,088)	(10,642)
Expenses:
Rental operations		0		0	0	0
General and administrative		(4,113)		(3,577)	(12,088)	(10,642)
Interest		0		0	0	0
Depreciation and amortization		0		0	0	0
Impairment of real estate					0
Loss on early extinguishment of debt				0	0	0
Total expenses		(4,113)		(3,577)	(12,088)	(10,642)
Equity in earnings of unconsolidated joint ventures		0			0
Income (Loss) from Subsidiaries, before Tax		(137,177)		(119,923)	(371,726)	(356,620)
Income from continuing operations				(119,923)	(371,726)	(356,620)
(Loss) income from discontinued operations, net				0	0	0
Gain on sales of real estate – land parcels				0		0
Net income		(137,177)		(119,923)	(371,726)	(356,620)
Dividends on preferred stock		0		0	0	0
Net income attributable to noncontrolling interests		0		0	0	0
Net income attributable to unvested restricted stock awards		0		0	0	0
Net income attributable to Alexandria’s common stockholders		$ (137,177)		$ (119,923)	$ (371,726)	$ (356,620)