Earnings per share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Earnings per share
Income from continuing operations	$ 36,115		$ 32,496		$ 112,492		$ 94,212
Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes	8		0		805		772
Dividends on preferred stock	(6,471)		(6,472)		(19,414)		(19,414)
Net income attributable to noncontrolling interests	(1,340)		(960)		(3,842)		(2,922)
Participating Securities, Distributed and Undistributed Earnings (Loss), Diluted	(506)		(442)		(1,285)		(1,187)
Income from continuing operations attributable to Alexandria Real Estate Equities, Inc.'s common stockholders - basic and diluted	27,806		24,622		88,756		71,461
(Loss) income from discontinued operations, net	(180)	[1]	(43)	[1]	(489)	[1]	1,043	[1]
Net income attributable to Alexandria’s common stockholders	$ 27,626		$ 24,579		$ 88,267		$ 72,504
Weighted average shares of common stock outstanding – basic and diluted	71,195		70,900		71,121		67,040
Earnings per share attributable to Alexandria Real Estate Equities, Inc.'s common stockholders - basic and diluted:
Continuing operations	$ 0.39		$ 0.35		$ 1.25		$ 1.06
Discontinued operations	$ 0.00		$ 0.00		$ (0.01)		$ 0.02
Earnings per share – basic and diluted	$ 0.39		$ 0.35		$ 1.24		$ 1.08

[1] includes the results of operations of four properties that were classified as “held for sale” as of September 30, 2014, as well as the results of operations (prior to disposition) and gain on sale of real estate attributable to seven properties sold during the period from January 1, 2013, to September 30, 2014. In October 2014, we completed the sale of one property which was classified as “held for sale” as of September 30, 2014.