Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 141,518	$ 47,555
Unrealized gains on public investments:
Unrealized holding gains (losses) arising during the period	0	10,421
Reclassification adjustment for losses included in net income	0	133
Unrealized gains on public investments, net	0	10,554
Unrealized gains on interest rate hedge agreements:
Unrealized interest rate hedge gains arising during the period	1,982	1,217
Reclassification adjustment for amortization of interest (income) expense included in net income	(678)	905
Unrealized gains (losses) on interest rate swap agreements, net	1,304	2,122
Unrealized (losses) gains on foreign currency translation:
Unrealized foreign currency translation (losses) gains arising during the period	(329)	1,012
Reclassification adjustment for cumulative foreign currency translation losses included in net income upon sale or liquidation	0	2,421
Unrealized (losses) gains on foreign currency translation, net	(329)	3,433
Total other comprehensive income	975	16,109
Comprehensive income (loss)	142,493	63,664
Less: comprehensive income attributable to noncontrolling interests	(5,888)	(5,848)
Comprehensive income attributable to Alexandria Real Estate Equities, Inc.’s common stockholders	$ 136,605	$ 57,816