Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues	$ 340,463	$ 341,823	$ 325,034	$ 320,139	$ 298,791	$ 285,370	$ 273,059	$ 270,877	$ 1,327,459	$ 1,128,097	$ 921,706
Expenses:
Rental operations									381,120	325,609	278,408
General and administrative									90,405	75,009	63,884
Interest									157,495	128,645	106,953
Depreciation and amortization									477,661	416,783	313,390
Impairment of real estate									6,311	203	209,261
Loss on early extinguishment of debt									1,122	3,451	3,230
Total expenses									1,114,114	949,700	975,126
Equity in earnings (losses) of unconsolidated real estate joint ventures									43,981	15,426	(184)
Investment income									136,763	0	0
Gain on sales of real estate – rental properties									8,704	270	3,715
Gain on sales of real estate - land parcels									0	111	90
Net income (loss)									402,793	194,204	(49,799)
Net income attributable to noncontrolling interest									(23,481)	(25,111)	(16,102)
Net income (loss) attributable to Alexandria Real Estate Equities, Inc.'s stockholders									379,312	169,093	(65,901)
Dividends on preferred stock									(5,060)	(7,666)	(20,223)
Preferred stock redemption charge									(4,240)	(11,279)	(61,267)
Net income attributable to unvested restricted stock awards									(6,029)	(4,753)	(3,750)
Net Income (loss) attributable to Alexandria Real Estate Equities, Inc.'s common stockholders	$ (31,740)	$ 208,940	$ 52,016	$ 132,387	$ 36,831	$ 51,273	$ 31,630	$ 25,661	$ 363,983	$ 145,395	$ (151,141)
Earnings per share attributable to Alexandria's common stockholders - basic and diluted
Earnings per share - basic (USD per share)	$ (0.30)	$ 2.01	$ 0.51	$ 1.33	$ 0.39	$ 0.55	$ 0.35	$ 0.29	$ 3.53	$ 1.59	$ (1.99)
Earnings per share - diluted (USD per share)	$ (0.30)	$ 1.99	$ 0.51	$ 1.32	$ 0.38	$ 0.55	$ 0.35	$ 0.29	$ 3.52	$ 1.58	$ (1.99)
Rental revenues
Revenues									$ 1,010,718	$ 863,181	$ 673,820
Tenant recoveries
Revenues									304,063	259,144	223,655
Other income
Revenues									$ 12,678	$ 5,772	$ 24,231