Condensed consolidating financial information (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Net income	$ 25,641	$ 34,311	$ 58,416	$ 66,936
Unrealized gains (losses) on marketable securities:
Unrealized holding gains (losses) arising during the period	(107)	(501)	567	12
Reclassification adjustment for gains included in net income	238		(686)
Unrealized gains (losses) on marketable securities, net	131	(501)	(119)	12
Unrealized gains (losses) on interest rate swaps:
Unrealized interest rate swap losses arising during the period	(3,091)	(5,555)	(7,164)	(5,255)
Reclassification adjustment for amortization of interest expense included in net income	5,895	5,302	11,670	10,741
Unrealized gain on interest rate swaps, net	2,804	(253)	4,506	5,486
Foreign currency translation (losses) gains	(17,192)	1,676	(7,233)	6,559
Total other comprehensive (loss) income	(14,257)	922	(2,846)	12,057
Comprehensive income	11,384	35,233	55,570	78,993
Less: comprehensive income attributable to noncontrolling interests	(875)	(939)	(1,574)	(1,861)
Comprehensive income attributable to Alexandria Real Estate Equities, Inc.'s common stockholders	10,509	34,294	53,996	77,132
Alexandria Real Estate Equities, Inc. (Issuer)
Net income	24,790	33,373	56,854	65,069
Unrealized gains (losses) on interest rate swaps:
Unrealized interest rate swap losses arising during the period	(3,091)	(5,555)	(7,164)	(5,255)
Reclassification adjustment for amortization of interest expense included in net income	5,895	5,302	11,670	10,741
Unrealized gain on interest rate swaps, net	2,804	(253)	4,506	5,486
Total other comprehensive (loss) income	2,804	(253)	4,506	5,486
Comprehensive income	27,594	33,120	61,360	70,555
Comprehensive income attributable to Alexandria Real Estate Equities, Inc.'s common stockholders	27,594	33,120	61,360	70,555
Alexandria Real Estate Equities, L.P. (Guarantor Subsidiary)
Net income	44,678	51,700	94,618	102,000
Unrealized gains (losses) on marketable securities:
Unrealized holding gains (losses) arising during the period	74	(501)	106	12
Reclassification adjustment for gains included in net income	75		64
Unrealized gains (losses) on marketable securities, net	149	(501)	170	12
Unrealized gains (losses) on interest rate swaps:
Total other comprehensive (loss) income	149	(501)	170	12
Comprehensive income	44,827	51,199	94,788	102,012
Comprehensive income attributable to Alexandria Real Estate Equities, Inc.'s common stockholders	44,827	51,199	94,788	102,012
Non-Guarantor Subsidiaries
Net income	51,120	56,748	104,498	112,098
Unrealized gains (losses) on marketable securities:
Unrealized holding gains (losses) arising during the period	(181)		461
Reclassification adjustment for gains included in net income	163		(750)
Unrealized gains (losses) on marketable securities, net	(18)		(289)
Unrealized gains (losses) on interest rate swaps:
Foreign currency translation (losses) gains	(17,192)	1,676	(7,233)	6,559
Total other comprehensive (loss) income	(17,210)	1,676	(7,522)	6,559
Comprehensive income	33,910	58,424	96,976	118,657
Less: comprehensive income attributable to noncontrolling interests	(875)	(939)	(1,574)	(1,861)
Comprehensive income attributable to Alexandria Real Estate Equities, Inc.'s common stockholders	33,035	57,485	95,402	116,796
Eliminations
Net income	(94,947)	(107,510)	(197,554)	(212,231)
Unrealized gains (losses) on interest rate swaps:
Comprehensive income	(94,947)	(107,510)	(197,554)	(212,231)
Comprehensive income attributable to Alexandria Real Estate Equities, Inc.'s common stockholders	$ (94,947)	$ (107,510)	$ (197,554)	$ (212,231)