Condensed consolidating financial information Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Net income	$ 25,008	$ 40,749
Unrealized (losses) gains on marketable securities:
Unrealized holding gains arising during the period	28,435	18,779
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Net of Tax	1,103	0
Unrealized gains on marketable securities, net	29,538	18,779
Unrealized (losses) gains on interest rate swap agreements:
Unrealized interest rate swap losses arising during the period	(3,013)	5,592
Reclassification adjustment for amortization of interest expense included in net income	505	(3,490)
Unrealized gains on interest rate swap agreements, net	(2,508)	2,102
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	(6,271)	(3,106)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax	9,236	0
Unrealized foreign currency translation losses arising during the period	2,965	(3,106)
Total other comprehensive income (loss)	29,995	17,775
Comprehensive income	55,003	58,524
Less: comprehensive income attributable to noncontrolling interests	(646)	(1,195)
Comprehensive income attributable to Alexandria’s common stockholders	54,357	57,329
Alexandria Real Estate Equities, Inc. (Issuer)
Net income	24,516	39,554
Unrealized (losses) gains on marketable securities:
Unrealized holding gains arising during the period	0	0
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Net of Tax	0	0
Unrealized gains on marketable securities, net	0	0
Unrealized (losses) gains on interest rate swap agreements:
Unrealized interest rate swap losses arising during the period	(3,013)	5,592
Reclassification adjustment for amortization of interest expense included in net income	505	(3,490)
Unrealized gains on interest rate swap agreements, net	(2,508)	2,102
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax	0
Unrealized foreign currency translation losses arising during the period	0	0
Total other comprehensive income (loss)	(2,508)	2,102
Comprehensive income	22,008	41,656
Less: comprehensive income attributable to noncontrolling interests	0	0
Comprehensive income attributable to Alexandria’s common stockholders	22,008	41,656
Alexandria Real Estate Equities, L.P. (Guarantor Subsidiary)
Net income	45,549	58,306
Unrealized (losses) gains on marketable securities:
Unrealized holding gains arising during the period	(54)	0
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Net of Tax	41	0
Unrealized gains on marketable securities, net	(13)	0
Unrealized (losses) gains on interest rate swap agreements:
Unrealized interest rate swap losses arising during the period	0	0
Reclassification adjustment for amortization of interest expense included in net income	0	0
Unrealized gains on interest rate swap agreements, net	0	0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax	0
Unrealized foreign currency translation losses arising during the period	0	0
Total other comprehensive income (loss)	(13)	0
Comprehensive income	45,536	58,306
Less: comprehensive income attributable to noncontrolling interests	0	0
Comprehensive income attributable to Alexandria’s common stockholders	45,536	58,306
Combined Non- Guarantor Subsidiaries
Net income	53,570	64,848
Unrealized (losses) gains on marketable securities:
Unrealized holding gains arising during the period	28,489	18,779
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Net of Tax	1,062	0
Unrealized gains on marketable securities, net	29,551	18,779
Unrealized (losses) gains on interest rate swap agreements:
Unrealized interest rate swap losses arising during the period	0	0
Reclassification adjustment for amortization of interest expense included in net income	0	0
Unrealized gains on interest rate swap agreements, net	0	0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	(6,271)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax	9,236
Unrealized foreign currency translation losses arising during the period	2,965	(3,106)
Total other comprehensive income (loss)	32,516	15,673
Comprehensive income	86,086	80,521
Less: comprehensive income attributable to noncontrolling interests	(646)	(1,195)
Comprehensive income attributable to Alexandria’s common stockholders	85,440	79,326
Eliminations
Net income	(98,627)	(121,959)
Unrealized (losses) gains on marketable securities:
Unrealized holding gains arising during the period	0	0
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Net of Tax	0	0
Unrealized gains on marketable securities, net	0	0
Unrealized (losses) gains on interest rate swap agreements:
Unrealized interest rate swap losses arising during the period	0	0
Reclassification adjustment for amortization of interest expense included in net income	0	0
Unrealized gains on interest rate swap agreements, net	0	0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax	0
Unrealized foreign currency translation losses arising during the period	0	0
Total other comprehensive income (loss)	0	0
Comprehensive income	(98,627)	(121,959)
Less: comprehensive income attributable to noncontrolling interests	0	0
Comprehensive income attributable to Alexandria’s common stockholders	$ (98,627)	$ (121,959)