Condensed consolidating financial information Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net income (loss)	$ 59,546	$ 28,559	$ 148,597	$ (69,591)
Unrealized gains (losses) on available-for-sale equity securities:
Unrealized holding gains (losses) arising during the period	17,018	(38,621)	23,414	(70,055)
Reclassification adjustment for losses included in net income	0	(8,540)	2,482	(18,627)
Unrealized gains (losses) on available-for-sale equity securities, net	17,018	(47,161)	25,896	(88,682)
Unrealized gains (losses) on interest rate hedge agreements:
Unrealized interest rate hedge gains (losses) arising during the period	145	2,982	812	(7,655)
Reclassification adjustment for amortization of interest expense included in net income	198	1,702	1,810	3,725
Unrealized gains (losses) on interest rate swap agreements, net	343	4,684	2,622	(3,930)
Unrealized gains on foreign currency translation:
Unrealized foreign currency translation gains (losses) arising during the period	3,836	(1,322)	7,592	842
Reclassification adjustment for cumulative foreign currency translation losses included in net income (loss) upon sale or liquidation	0	3,779	2,421	10,807
Unrealized gains on foreign currency translation, net	3,836	2,457	10,013	11,649
Total other comprehensive income (loss)	21,197	(40,020)	38,531	(80,963)
Comprehensive income (loss)	80,743	(11,461)	187,128	(150,554)
Less: comprehensive income attributable to noncontrolling interests	(5,783)	(4,081)	(18,914)	(11,587)
Comprehensive income (loss) attributable to Alexandria Real Estate Equities, Inc.’s common stockholders	74,960	(15,542)	168,214	(162,141)
Eliminations
Net income (loss)	(183,488)	(121,868)	(499,473)	(19,509)
Unrealized gains (losses) on available-for-sale equity securities:
Unrealized holding gains (losses) arising during the period	0	0	0	0
Reclassification adjustment for losses included in net income	0	0	0	0
Unrealized gains (losses) on available-for-sale equity securities, net	0	0	0	0
Unrealized gains (losses) on interest rate hedge agreements:
Unrealized interest rate hedge gains (losses) arising during the period	0	0	0	0
Reclassification adjustment for amortization of interest expense included in net income	0	0	0	0
Unrealized gains (losses) on interest rate swap agreements, net	0	0	0	0
Unrealized gains on foreign currency translation:
Unrealized foreign currency translation gains (losses) arising during the period	0	0	0	0
Reclassification adjustment for cumulative foreign currency translation losses included in net income (loss) upon sale or liquidation	0	0	0	0
Unrealized gains on foreign currency translation, net	0	0	0	0
Total other comprehensive income (loss)	0	0	0	0
Comprehensive income (loss)	(183,488)	(121,868)	(499,473)	(19,509)
Less: comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to Alexandria Real Estate Equities, Inc.’s common stockholders	(183,488)	(121,868)	(499,473)	(19,509)
Alexandria Real Estate Equities, Inc. (Issuer)
Net income (loss)	53,773	24,475	129,705	(81,205)
Unrealized gains (losses) on available-for-sale equity securities:
Unrealized holding gains (losses) arising during the period	0	0	0	0
Reclassification adjustment for losses included in net income	0	0	0	0
Unrealized gains (losses) on available-for-sale equity securities, net	0	0	0	0
Unrealized gains (losses) on interest rate hedge agreements:
Unrealized interest rate hedge gains (losses) arising during the period	174	2,979	1,062	(7,658)
Reclassification adjustment for amortization of interest expense included in net income	195	1,714	1,804	3,737
Unrealized gains (losses) on interest rate swap agreements, net	369	4,693	2,866	(3,921)
Unrealized gains on foreign currency translation:
Unrealized foreign currency translation gains (losses) arising during the period	0	0	0	0
Reclassification adjustment for cumulative foreign currency translation losses included in net income (loss) upon sale or liquidation	0	0	0	0
Unrealized gains on foreign currency translation, net	0	0	0	0
Total other comprehensive income (loss)	369	4,693	2,866	(3,921)
Comprehensive income (loss)	54,142	29,168	132,571	(85,126)
Less: comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to Alexandria Real Estate Equities, Inc.’s common stockholders	54,142	29,168	132,571	(85,126)
Alexandria Real Estate Equities, L.P. (Guarantor Subsidiary)
Net income (loss)	86,311	55,623	239,768	(6,167)
Unrealized gains (losses) on available-for-sale equity securities:
Unrealized holding gains (losses) arising during the period	65	58	20	136
Reclassification adjustment for losses included in net income	0	(159)	4	(148)
Unrealized gains (losses) on available-for-sale equity securities, net	65	(101)	24	(12)
Unrealized gains (losses) on interest rate hedge agreements:
Unrealized interest rate hedge gains (losses) arising during the period	0	0	0	0
Reclassification adjustment for amortization of interest expense included in net income	0	0	0	0
Unrealized gains (losses) on interest rate swap agreements, net	0	0	0	0
Unrealized gains on foreign currency translation:
Unrealized foreign currency translation gains (losses) arising during the period	0	0	0	0
Reclassification adjustment for cumulative foreign currency translation losses included in net income (loss) upon sale or liquidation	0	0	0	0
Unrealized gains on foreign currency translation, net	0	0	0	0
Total other comprehensive income (loss)	65	(101)	24	(12)
Comprehensive income (loss)	86,376	55,522	239,792	(6,179)
Less: comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income (loss) attributable to Alexandria Real Estate Equities, Inc.’s common stockholders	86,376	55,522	239,792	(6,179)
Combined Non- Guarantor Subsidiaries
Net income (loss)	102,950	70,329	278,597	37,290
Unrealized gains (losses) on available-for-sale equity securities:
Unrealized holding gains (losses) arising during the period	16,953	(38,679)	23,394	(70,191)
Reclassification adjustment for losses included in net income	0	(8,381)	2,478	(18,479)
Unrealized gains (losses) on available-for-sale equity securities, net	16,953	(47,060)	25,872	(88,670)
Unrealized gains (losses) on interest rate hedge agreements:
Unrealized interest rate hedge gains (losses) arising during the period	(29)	3	(250)	3
Reclassification adjustment for amortization of interest expense included in net income	3	(12)	6	(12)
Unrealized gains (losses) on interest rate swap agreements, net	(26)	(9)	(244)	(9)
Unrealized gains on foreign currency translation:
Unrealized foreign currency translation gains (losses) arising during the period	3,836	(1,322)	7,592	842
Reclassification adjustment for cumulative foreign currency translation losses included in net income (loss) upon sale or liquidation	0	3,779	2,421	10,807
Unrealized gains on foreign currency translation, net	3,836	2,457	10,013	11,649
Total other comprehensive income (loss)	20,763	(44,612)	35,641	(77,030)
Comprehensive income (loss)	123,713	25,717	314,238	(39,740)
Less: comprehensive income attributable to noncontrolling interests	(5,783)	(4,081)	(18,914)	(11,587)
Comprehensive income (loss) attributable to Alexandria Real Estate Equities, Inc.’s common stockholders	$ 117,930	$ 21,636	$ 295,324	$ (51,327)