Earnings per share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended															12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012	Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Earnings per share
Income from continuing operations																$ 134,525		$ 94,848		$ 117,270
Gain on sale of land parcel																4,824		1,864		46
Net income attributable to noncontrolling interests																(4,032)		(3,402)		(3,975)
Dividends on preferred stock																(25,885)		(27,328)		(28,357)
Preferred stock redemption charge																0		(5,978)		0
Net income attributable to unvested restricted stock awards																(1,581)		(1,190)		(1,088)
Income from continuing operations attributable to Alexandria Real Estate Equities, Inc.'s common stockholders - basic and diluted																107,851		58,814		83,896
(Loss) income from discontinued operations, net																900	[1]	8,816	[1]	18,077	[1]
Net income attributable to Alexandria’s common stockholders	$ 36,247		$ 24,579		$ 25,483		$ 22,442		$ 21,000	$ 10,646		$ 17,616		$ 18,368		$ 108,751		$ 67,630		$ 101,973
Weighted average shares of common stock outstanding – basic and diluted																68,038		62,160		59,078
Earnings per share attributable to Alexandria Real Estate Equities, Inc.'s common stockholders - basic and diluted:
Continuing operations																$ 1.59		$ 0.95		$ 1.42
Discontinued operations																$ 0.01		$ 0.14		$ 0.31
Earnings per share – basic and diluted	$ 0.51	[2]	$ 0.35	[2]	$ 0.38	[2]	$ 0.36	[2]	$ 0.33	$ 0.17	[2]	$ 0.29	[2]	$ 0.30	[2]	$ 1.60		$ 1.09		$ 1.73
8.00% Unsecured Senior Convertible Notes
Debt Instrument [Line Items]
Stated interest rate (as a percent)	8.00%															8.00%
Unsecured Senior 3.70 Percent Convertible Notes
Debt Instrument [Line Items]
Stated interest rate (as a percent)	3.70%															3.70%
Conversion price (in dollars per share)																				$ 117.36

[1] Income from discontinued operations includes the results of operations of four properties that were classified as “held for sale” as of December 31, 2013, as well as the results of operations (prior to disposition) and gain/loss on sale of real estate attributable to 14 properties sold during the period from January 1, 2011, to December 31, 2013.

[2] Quarterly earnings per common share amounts may not total to the annual amounts due to rounding and due to the increase in the weighted average shares of common stock outstanding.