Consolidated and unconsolidated real estate joint ventures (Details)	1 Months Ended					12 Months Ended
	Dec. 31, 2021 USD ($) ft²	Oct. 31, 2021 USD ($) ft²	Aug. 31, 2021 USD ($) ft²	Jul. 31, 2021 USD ($)	Apr. 30, 2021 USD ($)	Dec. 31, 2021 USD ($) ft²	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2021
Schedule of Equity Method Investments
Contributions from and sales of noncontrolling interests						$ 2,147,061,000	$ 717,158,000	$ 1,134,939,000
Contributions from and sales of noncontrolling interests						2,026,486,000	367,613,000	1,022,712,000
Payments to Noncontrolling Interests						$ 118,891,000	88,805,000	48,225,000
50 and 60 Binney Street
Schedule of Equity Method Investments
Equity interest percentage (in percent)	34.00%					34.00%
Contributions from and sales of noncontrolling interests	$ 782,300,000
Proceeds from sale of real estate, per RSF	$ 2,226
75/125 Binney Street
Schedule of Equity Method Investments
Equity interest percentage (in percent)	40.00%					40.00%
225 Binney Street
Schedule of Equity Method Investments
Equity interest percentage (in percent)	30.00%					30.00%
225 Binney Street | Alexandria
Schedule of Equity Method Investments
Equity interest percentage (in percent)	26.316%					26.316%
225 Binney Street | Tenancy in Common
Schedule of Equity Method Investments
Equity interest percentage (in percent)	73.684%					73.684%
99 Coolidge Avenue
Schedule of Equity Method Investments
Equity interest percentage (in percent)	75.00%					75.00%
409/499 Illinois Street
Schedule of Equity Method Investments
Equity interest percentage (in percent)	25.00%	25.00%				25.00%			35.00%
Proceeds from Sale of Real Estate		$ 495,600,000
Contributions from and sales of noncontrolling interests		$ 231,000,000
1500 Owens Street
Schedule of Equity Method Investments
Equity interest percentage (in percent)	25.00%	25.00%				25.00%			25.10%
Proceeds from Sale of Real Estate		$ 130,500,000
Contributions from and sales of noncontrolling interests		$ 43,700,000
1700 Owens Street
Schedule of Equity Method Investments
Equity interest percentage (in percent)	25.00%					25.00%
Contributions from and sales of noncontrolling interests	$ 381,400,000
Proceeds from sale of real estate, per RSF	$ 1,295
455 Mission Bay Boulevard South
Schedule of Equity Method Investments
Equity interest percentage (in percent)	25.00%					25.00%
Contributions from and sales of noncontrolling interests	$ 381,400,000
Proceeds from sale of real estate, per RSF	$ 1,295
Alexandria Technology Center - Gateway
Schedule of Equity Method Investments
Equity interest percentage (in percent)	49.90%					49.90%
213 East Grand Avenue
Schedule of Equity Method Investments
Equity interest percentage (in percent)	30.00%					30.00%
Contributions from and sales of noncontrolling interests					$ 301,000,000
Proceeds from sale of real estate, per RSF					1,429
500 Forbes Boulevard
Schedule of Equity Method Investments
Equity interest percentage (in percent)	10.00%					10.00%
Alexandria Center for Life Science – Millbrae Station
Schedule of Equity Method Investments
Equity interest percentage (in percent)	40.30%					40.30%
Alexandria Point
Schedule of Equity Method Investments
Equity interest percentage (in percent)	55.00%					55.00%
5200 Illumina Way
Schedule of Equity Method Investments
Equity interest percentage (in percent)	51.00%					51.00%
9625 Towne Centre Drive
Schedule of Equity Method Investments
Equity interest percentage (in percent)	50.10%					50.10%
SD Tech by Alexandria
Schedule of Equity Method Investments
Equity interest percentage (in percent)	50.00%					50.00%
Pacific Technology Park
Schedule of Equity Method Investments
Area of Real Estate Property | ft²			544,352
Equity interest percentage (in percent)	50.00%		50.00%			50.00%
Payments to Noncontrolling Interests			$ 85,800,000
1201 and 1208 Eastlake Avenue East and 199 East Blaine Street
Schedule of Equity Method Investments
Equity interest percentage (in percent)	30.00%					30.00%
400 Dexter Avenue North
Schedule of Equity Method Investments
Equity interest percentage (in percent)	30.00%					30.00%
Contributions from and sales of noncontrolling interests				$ 254,800,000
Proceeds from sale of real estate, per RSF				1,255
9444 Waples Street
Schedule of Equity Method Investments
Area of Real Estate Property | ft²			88,380
Contributions from and sales of noncontrolling interests			$ 11,500,000
Proceeds from sale of real estate, per RSF			$ 260
Equity Method Investee | 1655 and 1715 Third Street
Schedule of Equity Method Investments
Equity interest percentage (in percent)	10.00%					10.00%
Equity Method Investee | 1401/1413 Research Boulevard
Schedule of Equity Method Investments
Area of Real Estate Property | ft²	90,000					90,000
Equity interest percentage (in percent)	65.00%					65.00%
Equity Method Investee | 1450 Research Boulevard
Schedule of Equity Method Investments
Area of Real Estate Property | ft²		42,679
Equity interest percentage (in percent)		73.20%
Equity Method Investee | 101 West Dickman Street
Schedule of Equity Method Investments
Area of Real Estate Property | ft²		135,423
Equity interest percentage (in percent)		57.90%
Additional Paid-In Capital
Schedule of Equity Method Investments
Contributions from and sales of noncontrolling interests						$ 989,393,000	267,432,000	381,162,000
Additional Paid-In Capital | 50 and 60 Binney Street
Schedule of Equity Method Investments
Contributions from and sales of noncontrolling interests	$ 457,500,000
Additional Paid-In Capital | 409/499 Illinois Street
Schedule of Equity Method Investments
Contributions from and sales of noncontrolling interests		$ 92,400,000
Additional Paid-In Capital | 1500 Owens Street
Schedule of Equity Method Investments
Contributions from and sales of noncontrolling interests		$ 21,300,000
Additional Paid-In Capital | 1700 Owens Street
Schedule of Equity Method Investments
Contributions from and sales of noncontrolling interests	221,900,000
Additional Paid-In Capital | 455 Mission Bay Boulevard South
Schedule of Equity Method Investments
Contributions from and sales of noncontrolling interests	$ 221,900,000
Additional Paid-In Capital | 213 East Grand Avenue
Schedule of Equity Method Investments
Contributions from and sales of noncontrolling interests					$ 103,700,000
Additional Paid-In Capital | 400 Dexter Avenue North
Schedule of Equity Method Investments
Contributions from and sales of noncontrolling interests				$ 95,500,000
Noncontrolling Interests
Schedule of Equity Method Investments
Contributions from and sales of noncontrolling interests						1,157,668,000	449,726,000	$ 753,777,000
Payments to Noncontrolling Interests						$ 112,400,000	$ 87,300,000
Noncontrolling Interests | 50 and 60 Binney Street | Alexandria
Schedule of Equity Method Investments
Noncontrolling interest share (in percentage)	66.00%					66.00%
Noncontrolling Interests | 409/499 Illinois Street | Alexandria
Schedule of Equity Method Investments
Noncontrolling interest share (in percentage)		75.00%							40.00%
Noncontrolling Interests | 1500 Owens Street | Alexandria
Schedule of Equity Method Investments
Noncontrolling interest share (in percentage)		75.00%							49.90%
Noncontrolling Interests | 1700 Owens Street | Alexandria
Schedule of Equity Method Investments
Noncontrolling interest share (in percentage)	75.00%					75.00%
Noncontrolling Interests | 455 Mission Bay Boulevard South | Alexandria
Schedule of Equity Method Investments
Noncontrolling interest share (in percentage)	75.00%					75.00%
Noncontrolling Interests | 213 East Grand Avenue | Alexandria
Schedule of Equity Method Investments
Noncontrolling interest share (in percentage)					70.00%
Noncontrolling Interests | Pacific Technology Park | Alexandria
Schedule of Equity Method Investments
Noncontrolling interest share (in percentage)			50.00%						50.00%
Noncontrolling Interests | 400 Dexter Avenue North | Alexandria
Schedule of Equity Method Investments
Noncontrolling interest share (in percentage)				70.00%