Condensed consolidating financial information Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Net income	$ 39,699	$ 35,943	$ 103,137	$ 112,808
Unrealized losses on marketable equity securities:
Unrealized holding losses arising during the period	(29,832)	(2,454)	54,004	13,591
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Net of Tax	(4,968)	111	(2,503)	517
Unrealized (losses) gains on marketable equity securities, net	(34,800)	(2,343)	51,501	14,108
Unrealized (losses) gains on interest rate swap agreements:
Unrealized interest rate swap losses arising during the period	(5,474)	1,206	(9,712)	(2,708)
Reclassification adjustment for amortization of interest expense included in net income	727	1,129	1,942	5,742
Unrealized gains on interest rate swap agreements, net	(4,747)	2,335	(7,770)	3,034
Unrealized foreign currency translation losses arising during the period	(9,294)	(12,259)	(17,072)	(9,450)
Reclassification adjustment for (gains) losses included in net income	0	(199)	9,236	(199)
Unrealized foreign currency translation losses arising during the period	(9,294)	(12,458)	(7,836)	(9,649)
Total other comprehensive (loss) income	(48,841)	(12,466)	35,895	7,493
Comprehensive income	(9,142)	23,477	139,032	120,301
Less: comprehensive income attributable to noncontrolling interests	(71)	(1,340)	(954)	(3,842)
Comprehensive (loss) income attributable to Alexandria’s common stockholders	(9,213)	22,137	138,078	116,459
Alexandria Real Estate Equities, Inc. (Issuer)
Net income	39,529	34,603	102,212	108,966
Unrealized losses on marketable equity securities:
Unrealized holding losses arising during the period	0	0	0	0
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Net of Tax	0	0	0	0
Unrealized (losses) gains on marketable equity securities, net	0	0	0	0
Unrealized (losses) gains on interest rate swap agreements:
Unrealized interest rate swap losses arising during the period	(5,474)	1,206	(9,712)	(2,708)
Reclassification adjustment for amortization of interest expense included in net income	727	1,129	1,942	5,742
Unrealized gains on interest rate swap agreements, net	(4,747)	2,335	(7,770)	3,034
Unrealized foreign currency translation losses arising during the period	0	0	0	0
Reclassification adjustment for (gains) losses included in net income		0	0	0
Unrealized foreign currency translation losses arising during the period	0	0	0	0
Total other comprehensive (loss) income	(4,747)	2,335	(7,770)	3,034
Comprehensive income	34,782	36,938	94,442	112,000
Less: comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive (loss) income attributable to Alexandria’s common stockholders	34,782	36,938	94,442	112,000
Alexandria Real Estate Equities, L.P. (Guarantor Subsidiary)
Net income	63,877	57,117	174,672	170,190
Unrealized losses on marketable equity securities:
Unrealized holding losses arising during the period	(41)	(310)	(19)	0
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Net of Tax	(117)	0	(76)	0
Unrealized (losses) gains on marketable equity securities, net	(158)	(310)	(95)	0
Unrealized (losses) gains on interest rate swap agreements:
Unrealized interest rate swap 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 on interest rate swap agreements, net	0	0	0	0
Unrealized foreign currency translation losses arising during the period	0	0	0	0
Reclassification adjustment for (gains) losses included in net income		0	0	0
Unrealized foreign currency translation losses arising during the period	0	0	0	0
Total other comprehensive (loss) income	(158)	(310)	(95)	0
Comprehensive income	63,719	56,807	174,577	170,190
Less: comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive (loss) income attributable to Alexandria’s common stockholders	63,719	56,807	174,577	170,190
Combined Non- Guarantor Subsidiaries
Net income	73,470	64,146	197,979	190,272
Unrealized losses on marketable equity securities:
Unrealized holding losses arising during the period	(29,791)	(2,144)	54,023	13,591
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Net of Tax	(4,851)	111	(2,427)	517
Unrealized (losses) gains on marketable equity securities, net	(34,642)	(2,033)	51,596	14,108
Unrealized (losses) gains on interest rate swap agreements:
Unrealized interest rate swap 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 on interest rate swap agreements, net	0	0	0	0
Unrealized foreign currency translation losses arising during the period	(9,294)	(12,259)	(17,072)	(9,450)
Reclassification adjustment for (gains) losses included in net income		(199)	9,236	(199)
Unrealized foreign currency translation losses arising during the period	(9,294)	(12,458)	(7,836)	(9,649)
Total other comprehensive (loss) income	(43,936)	(14,491)	43,760	4,459
Comprehensive income	29,534	49,655	241,739	194,731
Less: comprehensive income attributable to noncontrolling interests	(71)	(1,340)	(954)	(3,842)
Comprehensive (loss) income attributable to Alexandria’s common stockholders	29,463	48,315	240,785	190,889
Eliminations
Net income	(137,177)	(119,923)	(371,726)	(356,620)
Unrealized losses on marketable equity securities:
Unrealized holding losses arising during the period	0	0	0	0
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Net of Tax	0	0	0	0
Unrealized (losses) gains on marketable equity securities, net	0	0	0	0
Unrealized (losses) gains on interest rate swap agreements:
Unrealized interest rate swap 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 on interest rate swap agreements, net	0	0	0	0
Unrealized foreign currency translation losses arising during the period	0	0	0	0
Reclassification adjustment for (gains) losses included in net income		0	0	0
Unrealized foreign currency translation losses arising during the period	0	0	0	0
Total other comprehensive (loss) income	0	0	0	0
Comprehensive income	(137,177)	(119,923)	(371,726)	(356,620)
Less: comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive (loss) income attributable to Alexandria’s common stockholders	$ (137,177)	$ (119,923)	$ (371,726)	$ (356,620)