Alexandria Real Estate Equities, Inc.'s stockholders' equity (Details) (USD $)	1 Months Ended			3 Months Ended		6 Months Ended		1 Months Ended
	Jun. 30, 2011	May 31, 2011	Sep. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011 Series C	Jun. 30, 2011 Series D Convertible	Jun. 30, 2010 8.00% Unsecured Convertible Notes
Stockholders' equity
Common stock, shares issued (in shares)		6,250,651	5,175,000
Shares issued upon full exercise of underwriters' over-allotment option (in shares)		750,651	675,000
Common stock, issue price (in dollars per share)		$ 75.50	$ 69.25
Proceeds from issuance of common stock		$ 451,500,000	$ 342,300,000			$ 451,539,000
Common stock shares issued pursuant to the terms of the Exchange Offer										5,620,256
Payment on exchange of unsecured convertible notes							43,528,000			41,900,000
Amount of unsecured convertible notes exchanged										232,700,000
Dividend declared on common stock	27,900,000
Dividend declared on common stock (in dollars per share)	$ 0.45			$ 0.45	$ 0.35	$ 0.90	$ 0.70
Dividend declared on preferred stock								$ 2,700,000	$ 4,400,000
Dividend declared on preferred stock (in dollars per share)								$ 0.5234375	$ 0.4375
Preferred Stock, Dividend Rate (as a percent)								8.375%