Quarterly financial data (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 223,955	$ 218,610	$ 204,156	$ 196,753	$ 188,674	$ 185,615	$ 176,402	$ 176,186	$ 843,474	$ 726,877	$ 631,151
Net income attributable to Alexandria Real Estate Equities, Inc.'s common stockholders	$ 35,131	$ 32,659	$ 31,291	$ 17,786	$ (16,154)	$ 27,626	$ 27,932	$ 32,709	$ 116,867	$ 72,113	$ 108,751
Earnings per share attributable to Alexandria’s common stockholders – basic and diluted:
Basic and diluted (1)	$ 0.49	$ 0.46	$ 0.44	$ 0.25	$ (0.23)	$ 0.39	$ 0.39	$ 0.46	$ 1.63	$ 1.01	$ 1.60
Net loss related to impairments of real estate and a preferred stock redemption charge, partially offset by gains on sales of real estate					$ 46,200
Net loss related to impairments of real estate and a preferred stock redemption charge, partially offset by gains on sales of real estate, per share					$ 0.65