Investments in real estate Investment in consolidated real estate joint ventures (Details) $ in Thousands	3 Months Ended	6 Months Ended	9 Months Ended
	Dec. 31, 2016 USD ($)	Mar. 31, 2017 USD ($)	Sep. 30, 2016 USD ($) ft²	Dec. 31, 2015 USD ($)	Jun. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)
Real Estate Properties [Line Items]
Noncontrolling Interest, Increase from Sale of Parent Equity Interest			$ 68,014
Investments in real estate			7,939,179	$ 7,629,922
Cash and cash equivalents			157,928	125,098	$ 76,383	$ 86,011
Other assets			206,133	133,312
Total assets			9,293,901	8,881,017
Secured notes payable			789,450	809,818
Total liabilities			5,000,980	4,587,053
Alexandria Real Estate Equities, Inc.’s share of equity			3,910,078	3,975,087
Noncontrolling interests’ share of equity			373,831	304,659
Total liabilities, noncontrolling interests, and equity			9,293,901	8,881,017
Primary Beneficiary
Real Estate Properties [Line Items]
Investments in real estate			802,266	608,474
Cash and cash equivalents			37,566	2,060
Other assets			40,863	37,633
Total assets			880,695	648,167
Secured notes payable			0	0
Other liabilities			75,865	38,666
Total liabilities			75,865	38,666
Alexandria Real Estate Equities, Inc.’s share of equity			432,735	307,220
Noncontrolling interests’ share of equity			372,095	302,281
Total liabilities, noncontrolling interests, and equity			$ 880,695	$ 648,167
ACLS at Campus Pointe [Member] | 10300 Campus Point Drive [Member]
Real Estate Properties [Line Items]
Area of Real Estate Property | ft²			449,759
ACLS at Campus Pointe [Member] | 10290 Campus Point Drive [Member]
Real Estate Properties [Line Items]
Area of Real Estate Property | ft²			304,326
Noncontrolling Interest, Increase from Sale of Parent Equity Interest			$ 68,600
Noncontrolling Interest - Historical Cost Basis			68,000
ACLS at Campus Pointe [Member] | 10290 Campus Point Drive [Member] | Additional Paid-In Capital
Real Estate Properties [Line Items]
Noncontrolling Interest, Increase from Sale of Parent Equity Interest			$ (537)
Scenario, Forecast [Member] | ACLS at Campus Pointe [Member] | 10300 Campus Point Drive [Member]
Real Estate Properties [Line Items]
Proceeds from Sale of Real Estate	$ 150,000
Scenario, Forecast [Member] | ACLS at Campus Pointe [Member] | 10290 Campus Point Drive [Member]
Real Estate Properties [Line Items]
Proceeds from Sale of Real Estate		$ 37,700