Condensed consolidating financial information Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Net income	$ 35,943	$ 32,453	$ 112,808	$ 96,027
Unrealized gains (losses) on marketable securities:
Unrealized holding (losses) gains arising during the period	(2,454)	(37)	13,591	323
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Net of Tax	111	(250)	517	(480)
Unrealized (losses) gains on marketable securities, net	(2,343)	(287)	14,108	(157)
Unrealized (losses) gains on interest rate swap agreements:
Unrealized interest rate swap losses arising during the period	1,206	(676)	(2,708)	(704)
Reclassification adjustment for amortization of interest expense included in net income	1,129	3,904	5,742	12,046
Unrealized gains on interest rate swap agreements, net	2,335	3,228	3,034	11,342
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	(12,259)	(3,404)	(9,450)	(26,461)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax	(199)	0	(199)	0
Foreign currency translation gains (losses)	(12,458)	(3,404)	(9,649)	(26,461)
Total other comprehensive income (loss)	(12,466)	(463)	7,493	(15,276)
Comprehensive income	23,477	31,990	120,301	80,751
Less: comprehensive income attributable to noncontrolling interests	(1,340)	(933)	(3,842)	(2,839)
Comprehensive income attributable to Alexandria’s common stockholders	22,137	31,057	116,459	77,912
Alexandria Real Estate Equities, Inc. (Issuer)
Net income	34,603	31,493	108,966	93,105
Unrealized gains (losses) on marketable securities:
Unrealized holding (losses) gains 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 securities, net	0	0	0	0
Unrealized (losses) gains on interest rate swap agreements:
Unrealized interest rate swap losses arising during the period	1,206	(676)	(2,708)	(704)
Reclassification adjustment for amortization of interest expense included in net income	1,129	3,904	5,742	12,046
Unrealized gains on interest rate swap agreements, net	2,335	3,228	3,034	11,342
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	0		0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax	0		0
Foreign currency translation gains (losses)	0	0	0	0
Total other comprehensive income (loss)	2,335	3,228	3,034	11,342
Comprehensive income	36,938	34,721	112,000	104,447
Less: comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income attributable to Alexandria’s common stockholders	36,938	34,721	112,000	104,447
Alexandria Real Estate Equities, L.P. (Guarantor Subsidiary)
Net income	57,117	48,476	170,190	144,518
Unrealized gains (losses) on marketable securities:
Unrealized holding (losses) gains arising during the period	(310)	(796)	0	(391)
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Net of Tax	0	519	0	144
Unrealized (losses) gains on marketable securities, net	(310)	(277)	0	(247)
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
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	0		0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax	0		0
Foreign currency translation gains (losses)	0	0	0	0
Total other comprehensive income (loss)	(310)	(277)	0	(247)
Comprehensive income	56,807	48,199	170,190	144,271
Less: comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income attributable to Alexandria’s common stockholders	56,807	48,199	170,190	144,271
Combined Non- Guarantor Subsidiaries
Net income	64,146	53,895	190,272	161,616
Unrealized gains (losses) on marketable securities:
Unrealized holding (losses) gains arising during the period	(2,144)	759	13,591	714
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Net of Tax	111	(769)	517	(624)
Unrealized (losses) gains on marketable securities, net	(2,033)	(10)	14,108	90
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
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	(12,259)		(9,450)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax	(199)		(199)
Foreign currency translation gains (losses)	(12,458)	(3,404)	(9,649)	(26,461)
Total other comprehensive income (loss)	(14,491)	(3,414)	4,459	(26,371)
Comprehensive income	49,655	50,481	194,731	135,245
Less: comprehensive income attributable to noncontrolling interests	(1,340)	(933)	(3,842)	(2,839)
Comprehensive income attributable to Alexandria’s common stockholders	48,315	49,548	190,889	132,406
Eliminations
Net income	(119,923)	(101,411)	(356,620)	(303,212)
Unrealized gains (losses) on marketable securities:
Unrealized holding (losses) gains 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 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
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	0		0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax	0		0
Foreign currency translation gains (losses)	0	0	0	0
Total other comprehensive income (loss)	0	0	0	0
Comprehensive income	(119,923)	(101,411)	(356,620)	(303,212)
Less: comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income attributable to Alexandria’s common stockholders	$ (119,923)	$ (101,411)	$ (356,620)	$ (303,212)