Earnings per share (Details) - USD ($) $ / shares in Units, shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Class of Stock [Line Items]
Dilutive Securities, Effect on Basic Earnings Per Share	$ 0	$ 0	$ 0	$ 0
Earnings per share
Income from continuing operations	39,699,000	36,115,000	103,180,000	112,492,000
Gain on sales of real estate – land parcels	0	8,000	0	805,000
Dividends on preferred stock	(6,247,000)	(6,471,000)	(18,740,000)	(19,414,000)
Net income attributable to noncontrolling interests	(170,000)	(1,340,000)	(925,000)	(3,842,000)
Participating Securities, Distributed and Undistributed Earnings (Loss), Diluted	(623,000)	(506,000)	(1,736,000)	(1,285,000)
Income from continuing operations attributable to Alexandria Real Estate Equities, Inc.'s common stockholders - basic and diluted	32,659,000	27,806,000	81,779,000	88,756,000
(Loss) income from discontinued operations, net	0	(180,000)	(43,000)	(489,000)
Net income attributable to Alexandria’s common stockholders	$ 32,659,000	$ 27,626,000	$ 81,736,000	$ 88,267,000
Weighted-average shares of common stock outstanding – basic and diluted	71,500	71,195	71,426	71,121
Earnings per share attributable to Alexandria Real Estate Equities, Inc.'s common stockholders - basic and diluted:
Continuing operations (usd per share)	$ 0.46	$ 0.39	$ 1.14	$ 1.25
Discontinued operations (usd per share)	0.00	0.00	0.00	(0.01)
Earnings per share – basic and diluted (usd per share)	$ 0.46	$ 0.39	$ 1.14	$ 1.24
Series D Convertible Preferred Stock
Class of Stock [Line Items]
Preferred Stock, Dividend Rate, Percentage			7.00%