Condensed consolidating financial information Income Statement (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Jun. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues:
Rental	$ 216,021	$ 166,591		$ 635,156	$ 486,505
Tenant recoveries	67,058	58,681		188,874	165,385
Other income	2,291	5,107		5,276	20,654
Total revenues	285,370	230,379		829,306	672,544
Expenses:
Rental operations	83,469	72,002		237,536	205,164
General and administrative	17,636	15,854		56,099	46,426
Interest	31,031	25,850		92,563	75,730
Depreciation and amortization	107,788	77,133		309,069	218,168
Impairment of real estate	0	8,114	$ 156,100	203	193,237
Loss on early extinguishment of debt	0	3,230		670	3,230
Total expenses	239,924	202,183		696,140	741,955
Equity in earnings (losses) of unconsolidated real estate joint ventures	14,100	273		15,050	(270)
Equity in earnings of affiliates	0	0		0	0
Gain (loss) on sale of real estate - rental properties	0	0		270	0
Gain (loss) on sale of real estate - land parcels	0	90		111	90
Net income (loss)	59,546	28,559		148,597	(69,591)
Net income attributable to noncontrolling interests	(5,773)	(4,084)		(18,892)	(11,614)
Net income (loss) attributable to Alexandria Real Estate Equities, Inc.’s stockholders	53,773	24,475		129,705	(81,205)
Dividends on preferred stock	(1,302)	(5,007)		(6,364)	(16,388)
Preferred stock redemption charge	0	(13,095)		(11,279)	(25,614)
Net income attributable to unvested restricted stock awards	(1,198)	(921)		(3,498)	(2,807)
Net income (loss) attributable to Alexandria Real Estate Equities, Inc.’s common stockholders	51,273	5,452		108,564	(126,014)
Contributions from and sale of noncontrolling interests				9,877	68,621
Eliminations
Revenues:
Rental	0	0		0	0
Tenant recoveries	0	0		0	0
Other income	(4,086)	(3,913)		(13,683)	(10,638)
Total revenues	(4,086)	(3,913)		(13,683)	(10,638)
Expenses:
Rental operations	0	0		0	0
General and administrative	(4,086)	(3,913)		(13,683)	(10,638)
Interest	0	0		0	0
Depreciation and amortization	0	0		0	0
Impairment of real estate		0		0	0
Loss on early extinguishment of debt		0		0	0
Total expenses	(4,086)	(3,913)		(13,683)	(10,638)
Equity in earnings (losses) of unconsolidated real estate joint ventures	0	0		0	0
Equity in earnings of affiliates	(183,488)	(121,868)		(499,473)	(19,509)
Gain (loss) on sale of real estate - rental properties	0			0
Gain (loss) on sale of real estate - land parcels		0		0	0
Net income (loss)	(183,488)	(121,868)		(499,473)	(19,509)
Net income attributable to noncontrolling interests	0	0		0	0
Net income (loss) attributable to Alexandria Real Estate Equities, Inc.’s stockholders	(183,488)	(121,868)		(499,473)	(19,509)
Dividends on preferred stock	0	0		0	0
Preferred stock redemption charge		0		0	0
Net income attributable to unvested restricted stock awards	0	0		0	0
Net income (loss) attributable to Alexandria Real Estate Equities, Inc.’s common stockholders	(183,488)	(121,868)		(499,473)	(19,509)
Contributions from and sale of noncontrolling interests				0	0
Alexandria Real Estate Equities, Inc. (Issuer)
Revenues:
Rental	0	0		0	0
Tenant recoveries	0	0		0	0
Other income	3,230	1,077		11,337	7,086
Total revenues	3,230	1,077		11,337	7,086
Expenses:
Rental operations	0	0		0	0
General and administrative	16,598	15,568		55,272	45,224
Interest	23,958	21,318		72,907	60,729
Depreciation and amortization	1,787	1,722		5,217	4,997
Impairment of real estate		0		0	0
Loss on early extinguishment of debt		3,230		670	3,230
Total expenses	42,343	41,838		134,066	114,180
Equity in earnings (losses) of unconsolidated real estate joint ventures	0	0		0	0
Equity in earnings of affiliates	92,886	65,236		252,434	25,889
Gain (loss) on sale of real estate - rental properties				0
Gain (loss) on sale of real estate - land parcels		0		0	0
Net income (loss)	53,773	24,475		129,705	(81,205)
Net income attributable to noncontrolling interests	0	0		0	0
Net income (loss) attributable to Alexandria Real Estate Equities, Inc.’s stockholders	53,773	24,475		129,705	(81,205)
Dividends on preferred stock	(1,302)	(5,007)		(6,364)	(16,388)
Preferred stock redemption charge		(13,095)		(11,279)	(25,614)
Net income attributable to unvested restricted stock awards	(1,198)	(921)		(3,498)	(2,807)
Net income (loss) attributable to Alexandria Real Estate Equities, Inc.’s common stockholders	51,273	5,452		108,564	(126,014)
Contributions from and sale of noncontrolling interests				0	0
Alexandria Real Estate Equities, L.P. (Guarantor Subsidiary)
Revenues:
Rental	0	0		0	0
Tenant recoveries	0	0		0	0
Other income	(2,589)	91		(2,577)	115
Total revenues	(2,589)	91		(2,577)	115
Expenses:
Rental operations	0	0		0	0
General and administrative	0	0		0	0
Interest	0	0		0	0
Depreciation and amortization	0	0		0	0
Impairment of real estate		0		0	0
Loss on early extinguishment of debt		0		0	0
Total expenses	0	0		0	0
Equity in earnings (losses) of unconsolidated real estate joint ventures	0	0		0	0
Equity in earnings of affiliates	88,900	55,532		242,345	(6,282)
Gain (loss) on sale of real estate - rental properties				0
Gain (loss) on sale of real estate - land parcels		0		0	0
Net income (loss)	86,311	55,623		239,768	(6,167)
Net income attributable to noncontrolling interests	0	0		0	0
Net income (loss) attributable to Alexandria Real Estate Equities, Inc.’s stockholders	86,311	55,623		239,768	(6,167)
Dividends on preferred stock	0	0		0	0
Preferred stock redemption charge		0		0	0
Net income attributable to unvested restricted stock awards	0	0		0	0
Net income (loss) attributable to Alexandria Real Estate Equities, Inc.’s common stockholders	86,311	55,623		239,768	(6,167)
Contributions from and sale of noncontrolling interests				0	0
Combined Non- Guarantor Subsidiaries
Revenues:
Rental	216,021	166,591		635,156	486,505
Tenant recoveries	67,058	58,681		188,874	165,385
Other income	5,736	7,852		10,199	24,091
Total revenues	288,815	233,124		834,229	675,981
Expenses:
Rental operations	83,469	72,002		237,536	205,164
General and administrative	5,124	4,199		14,510	11,840
Interest	7,073	4,532		19,656	15,001
Depreciation and amortization	106,001	75,411		303,852	213,171
Impairment of real estate		8,114		203	193,237
Loss on early extinguishment of debt		0		0	0
Total expenses	201,667	164,258		575,757	638,413
Equity in earnings (losses) of unconsolidated real estate joint ventures	14,100	273		15,050	(270)
Equity in earnings of affiliates	1,702	1,100		4,694	(98)
Gain (loss) on sale of real estate - rental properties				270
Gain (loss) on sale of real estate - land parcels		90		111	90
Net income (loss)	102,950	70,329		278,597	37,290
Net income attributable to noncontrolling interests	(5,773)	(4,084)		(18,892)	(11,614)
Net income (loss) attributable to Alexandria Real Estate Equities, Inc.’s stockholders	97,177	66,245		259,705	25,676
Dividends on preferred stock	0	0		0	0
Preferred stock redemption charge		0		0	0
Net income attributable to unvested restricted stock awards	0	0		0	0
Net income (loss) attributable to Alexandria Real Estate Equities, Inc.’s common stockholders	$ 97,177	$ 66,245		259,705	25,676
Contributions from and sale of noncontrolling interests				$ 9,877	$ 68,621