Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues	$ 408,114	$ 390,484	$ 373,856	$ 358,842	$ 340,463	$ 341,823	$ 325,034	$ 320,139	$ 1,531,296	$ 1,327,459	$ 1,128,097
Expenses:
Rental operations									445,492	381,120	325,609
General and administrative									108,823	90,405	75,009
Interest									173,675	157,495	128,645
Depreciation and amortization									544,612	477,661	416,783
Impairment of real estate									12,334	6,311	203
Loss on early extinguishment of debt									47,570	1,122	3,451
Total expenses									1,332,506	1,114,114	949,700
Equity in earnings (losses) of unconsolidated real estate joint ventures									10,136	43,981	15,426
Investment income									194,647	136,763	0
Gain on sales of real estate – rental properties									474	8,704	270
Gain on sales of real estate - land parcels									0	0	111
Net income (loss)									404,047	402,793	194,204
Net income attributable to noncontrolling interest									(40,882)	(23,481)	(25,111)
Net income (loss) attributable to Alexandria Real Estate Equities, Inc.'s stockholders									363,165	379,312	169,093
Dividends on preferred stock									(3,204)	(5,060)	(7,666)
Preferred stock redemption charge									(2,580)	(4,240)	(11,279)
Net income attributable to unvested restricted stock awards									(6,386)	(6,029)	(4,753)
Net Income (loss) attributable to Alexandria Real Estate Equities, Inc.'s common stockholders	$ 199,618	$ (49,773)	$ 76,330	$ 123,598	$ (31,740)	$ 208,940	$ 52,016	$ 132,387	$ 350,995	$ 363,983	$ 145,395
Earnings per share attributable to Alexandria's common stockholders - basic and diluted
Earnings per share - basic (USD per share)	$ 1.75	$ (0.44)	$ 0.68	$ 1.11	$ (0.30)	$ 2.01	$ 0.51	$ 1.33	$ 3.13	$ 3.53	$ 1.59
Earnings per share - diluted (USD per share)	$ 1.74	$ (0.44)	$ 0.68	$ 1.11	$ (0.30)	$ 1.99	$ 0.51	$ 1.32	$ 3.12	$ 3.52	$ 1.58
Income from rentals
Revenues									$ 1,516,864	$ 1,314,781	$ 1,122,325
Other income
Revenues									$ 14,432	$ 12,678	$ 5,772