Condensed consolidating financial information Cash Flows (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
Operating Activities
Net income	$ 35,943	$ 32,453	$ 112,808	$ 96,027
Depreciation, Depletion and Amortization			166,123	142,677
Adjustments to reconcile net income to net cash provided by operating activities:
Gains (Losses) on Extinguishment of Debt	525	1,432	525	1,992
Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes	(8)	0	(805)	(772)
Loss on sale of real estate	0	0	0	121
Amortization of loan fees and costs			8,090	7,300
Amortization of debt premiums/discounts			100	383
Amortization of above and below Market Leases			(2,191)	(2,490)
Deferred rent			(35,511)	(20,007)
Stock compensation expense			9,372	11,541
Equity in income related to subsidiaries			0	0
Investment gains	(3,256)	(2,050)	(9,481)	(4,716)
Investment losses	3,485	0	8,725	529
Changes in operating assets and liabilities:
Restricted cash			0	1,243
Tenant receivables			(939)	(271)
Deferred leasing costs			(25,910)	(37,190)
Other assets			(12,228)	(11,428)
Intercompany receivables and payables				0
Accounts payable, accrued expenses, and tenant security deposits			36,446	51,437
Net cash (used in) provided by operating activities			255,124	236,376
Investing Activities
Proceeds from sale of properties			28,378	101,815
Additions to properties			(345,074)	(450,140)
Purchase of properties			(97,785)	(24,537)
Payments for (Proceeds from) Deposits on Real Estate Acquisitions			(7,292)	0
Change in restricted cash related to construction projects			6,694	5,711
Contributions to unconsolidated real estate entity			(67,525)	(13,881)
Investments in subsidiaries			0	0
Additions to investments			(35,484)	(22,835)
Proceeds from investments			13,883	12,750
Proceeds from Collection of Notes Receivable			29,866	0
Net cash (used in) provided by investing activities			(474,339)	(391,117)
Financing Activities
Borrowings from secured notes payable			108,626	26,319
Repayments of borrowings from secured notes payable			(228,909)	(34,120)
Proceeds from Issuance of Unsecured Debt			698,908	498,561
Principal borrowings from unsecured senior line of credit			890,000	319,000
Repayments of borrowings from unsecured senior line of credit			(952,000)	(871,000)
Repayments of Unsecured Debt			(125,000)	(250,000)
Repayments of Convertible Debt			0	(384)
Transfers to/from parent company			0	0
Change in restricted cash related to financings			375	923
Deferred financing costs paid			(7,989)	(16,247)
Proceeds from Issuance of Common Stock			0	535,686
Dividends paid on common stock			(150,540)	(120,367)
Dividends paid on preferred stock			(19,414)	(19,414)
Proceeds from Noncontrolling Interests			19,410	0
Noncontrolling Interest, Increase from Subsidiary Equity Issuance			19,410
Payments of Distributions to Affiliates			(893)	0
Distributions to noncontrolling interests			(2,594)	(2,100)
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders			2,594
Net cash provided by (used in) financing activities			229,980	66,857
Effect of foreign exchange rate changes on cash and cash equivalents			(1,438)	752
Net increase in cash and cash equivalents			9,327	(87,132)
Cash and cash equivalents at beginning of period			57,696	140,971
Cash and cash equivalents at end of period	67,023	53,839	67,023	53,839
Supplemental Disclosure of Cash Flow Information
Cash paid during the period for interest, net of interest capitalized			33,783	34,281
Non-Cash Investing Activities
Note receivable from sale of real estate			0	38,820
Assumption of secured notes payable in connection with purchase of properties			48,329	0
Alexandria Real Estate Equities, Inc. (Issuer)
Operating Activities
Net income	34,603	31,493	108,966	93,105
Depreciation, Depletion and Amortization			4,335	4,393
Adjustments to reconcile net income to net cash provided by operating activities:
Gains (Losses) on Extinguishment of Debt	525	1,432	525	1,992
Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes	0		0	0
Loss on sale of real estate				0
Amortization of loan fees and costs			5,424	5,148
Amortization of debt premiums/discounts			152	75
Amortization of above and below Market Leases			0	0
Deferred rent			0	0
Stock compensation expense			9,372	11,541
Equity in income related to subsidiaries			(180,275)	(155,694)
Investment gains			0	0
Investment losses			0	0
Changes in operating assets and liabilities:
Restricted cash			(15)	(8)
Tenant receivables			0	1
Deferred leasing costs			(80)	2,421
Other assets			(5,263)	(5,570)
Intercompany receivables and payables				3,021
Accounts payable, accrued expenses, and tenant security deposits			50,210	(9,599)
Net cash (used in) provided by operating activities			(6,649)	(49,174)
Investing Activities
Proceeds from sale of properties			0	10,796
Additions to properties			0	3,539
Purchase of properties			0	0
Payments for (Proceeds from) Deposits on Real Estate Acquisitions			0
Change in restricted cash related to construction projects			0	0
Contributions to unconsolidated real estate entity			0	0
Investments in subsidiaries			(322,228)	(126,967)
Additions to investments			0	0
Proceeds from investments			0	0
Proceeds from Collection of Notes Receivable			0
Net cash (used in) provided by investing activities			(322,228)	(112,632)
Financing Activities
Borrowings from secured notes payable			0	0
Repayments of borrowings from secured notes payable			0	0
Proceeds from Issuance of Unsecured Debt			698,908	498,561
Principal borrowings from unsecured senior line of credit			890,000	319,000
Repayments of borrowings from unsecured senior line of credit			(952,000)	(871,000)
Repayments of Unsecured Debt			(125,000)	(250,000)
Repayments of Convertible Debt				(384)
Transfers to/from parent company			103	0
Change in restricted cash related to financings			0	(1)
Deferred financing costs paid			(6,515)	(14,175)
Proceeds from Issuance of Common Stock				535,686
Dividends paid on common stock			(150,540)	(120,367)
Dividends paid on preferred stock			(19,414)	(19,414)
Proceeds from Noncontrolling Interests			0
Payments of Distributions to Affiliates			0
Distributions to noncontrolling interests			0	0
Net cash provided by (used in) financing activities			335,542	77,906
Effect of foreign exchange rate changes on cash and cash equivalents			0	0
Net increase in cash and cash equivalents			6,665	(83,900)
Cash and cash equivalents at beginning of period			14,790	98,567
Cash and cash equivalents at end of period	21,455	14,667	21,455	14,667
Supplemental Disclosure of Cash Flow Information
Cash paid during the period for interest, net of interest capitalized			20,089	16,569
Non-Cash Investing Activities
Note receivable from sale of real estate				29,820
Assumption of secured notes payable in connection with purchase of properties			0
Alexandria Real Estate Equities, L.P. (Guarantor Subsidiary)
Operating Activities
Net income	57,117	48,476	170,190	144,518
Depreciation, Depletion and Amortization			0	0
Adjustments to reconcile net income to net cash provided by operating activities:
Gains (Losses) on Extinguishment of Debt	0	0	0	0
Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes	0		0	0
Loss on sale of real estate				0
Amortization of loan fees and costs			0	0
Amortization of debt premiums/discounts			0	0
Amortization of above and below Market Leases			0	0
Deferred rent			0	0
Stock compensation expense			0	0
Equity in income related to subsidiaries			(172,989)	(144,660)
Investment gains			(3)	(152)
Investment losses			2,802	298
Changes in operating assets and liabilities:
Restricted cash			0	0
Tenant receivables			0	0
Deferred leasing costs			0	0
Other assets			0	0
Intercompany receivables and payables				0
Accounts payable, accrued expenses, and tenant security deposits			0	0
Net cash (used in) provided by operating activities			0	4
Investing Activities
Proceeds from sale of properties			0	0
Additions to properties			0	0
Purchase of properties			0	0
Payments for (Proceeds from) Deposits on Real Estate Acquisitions			0
Change in restricted cash related to construction projects			0	0
Contributions to unconsolidated real estate entity			0	0
Investments in subsidiaries			(291,300)	(170,033)
Additions to investments			0	0
Proceeds from investments			0	1,594
Proceeds from Collection of Notes Receivable			0
Net cash (used in) provided by investing activities			(291,300)	(168,439)
Financing Activities
Borrowings from secured notes payable			0	0
Repayments of borrowings from secured notes payable			0	0
Proceeds from Issuance of Unsecured Debt			0	0
Principal borrowings from unsecured senior line of credit			0	0
Repayments of borrowings from unsecured senior line of credit			0	0
Repayments of Unsecured Debt			0	0
Repayments of Convertible Debt				0
Transfers to/from parent company			291,300	166,522
Change in restricted cash related to financings			0	0
Deferred financing costs paid			0	0
Proceeds from Issuance of Common Stock				0
Dividends paid on common stock			0	0
Dividends paid on preferred stock			0	0
Proceeds from Noncontrolling Interests			0
Payments of Distributions to Affiliates			0
Distributions to noncontrolling interests			0	0
Net cash provided by (used in) financing activities			291,300	166,522
Effect of foreign exchange rate changes on cash and cash equivalents			0	0
Net increase in cash and cash equivalents			0	(1,913)
Cash and cash equivalents at beginning of period			0	1,913
Cash and cash equivalents at end of period	0	0	0	0
Supplemental Disclosure of Cash Flow Information
Cash paid during the period for interest, net of interest capitalized			0	0
Non-Cash Investing Activities
Note receivable from sale of real estate				0
Assumption of secured notes payable in connection with purchase of properties			0
Combined Non- Guarantor Subsidiaries
Operating Activities
Net income	64,146	53,895	190,272	161,616
Depreciation, Depletion and Amortization			161,788	138,284
Adjustments to reconcile net income to net cash provided by operating activities:
Gains (Losses) on Extinguishment of Debt	0	0	0	0
Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes	(8)		(805)	(772)
Loss on sale of real estate				121
Amortization of loan fees and costs			2,666	2,152
Amortization of debt premiums/discounts			(52)	308
Amortization of above and below Market Leases			(2,191)	(2,490)
Deferred rent			(35,511)	(20,007)
Stock compensation expense			0	0
Equity in income related to subsidiaries			(3,356)	(2,858)
Investment gains			(9,478)	(4,564)
Investment losses			5,923	231
Changes in operating assets and liabilities:
Restricted cash			15	1,251
Tenant receivables			(939)	(272)
Deferred leasing costs			(25,830)	(39,611)
Other assets			(6,965)	(5,858)
Intercompany receivables and payables				(3,021)
Accounts payable, accrued expenses, and tenant security deposits			(13,764)	61,036
Net cash (used in) provided by operating activities			261,773	285,546
Investing Activities
Proceeds from sale of properties			28,378	91,019
Additions to properties			(345,074)	(453,679)
Purchase of properties			(97,785)	(24,537)
Payments for (Proceeds from) Deposits on Real Estate Acquisitions			(7,292)
Change in restricted cash related to construction projects			6,694	5,711
Contributions to unconsolidated real estate entity			(67,525)	(13,881)
Investments in subsidiaries			(12,150)	(3,045)
Additions to investments			(35,484)	(22,835)
Proceeds from investments			13,883	11,156
Proceeds from Collection of Notes Receivable			29,866
Net cash (used in) provided by investing activities			(486,489)	(410,091)
Financing Activities
Borrowings from secured notes payable			108,626	26,319
Repayments of borrowings from secured notes payable			(228,909)	(34,120)
Proceeds from Issuance of Unsecured Debt			0	0
Principal borrowings from unsecured senior line of credit			0	0
Repayments of borrowings from unsecured senior line of credit			0	0
Repayments of Unsecured Debt			0	0
Repayments of Convertible Debt				0
Transfers to/from parent company			334,275	133,523
Change in restricted cash related to financings			375	924
Deferred financing costs paid			(1,474)	(2,072)
Proceeds from Issuance of Common Stock				0
Dividends paid on common stock			0	0
Dividends paid on preferred stock			0	0
Proceeds from Noncontrolling Interests			19,410
Payments of Distributions to Affiliates			(893)
Distributions to noncontrolling interests			(2,594)	(2,100)
Net cash provided by (used in) financing activities			228,816	122,474
Effect of foreign exchange rate changes on cash and cash equivalents			(1,438)	752
Net increase in cash and cash equivalents			2,662	(1,319)
Cash and cash equivalents at beginning of period			42,906	40,491
Cash and cash equivalents at end of period	45,568	39,172	45,568	39,172
Supplemental Disclosure of Cash Flow Information
Cash paid during the period for interest, net of interest capitalized			13,694	17,712
Non-Cash Investing Activities
Note receivable from sale of real estate				9,000
Assumption of secured notes payable in connection with purchase of properties			(48,329)
Eliminations
Operating Activities
Net income	(119,923)	(101,411)	(356,620)	(303,212)
Depreciation, Depletion and Amortization			0	0
Adjustments to reconcile net income to net cash provided by operating activities:
Gains (Losses) on Extinguishment of Debt	0	0	0	0
Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes	0		0	0
Loss on sale of real estate				0
Amortization of loan fees and costs			0	0
Amortization of debt premiums/discounts			0	0
Amortization of above and below Market Leases			0	0
Deferred rent			0	0
Stock compensation expense			0	0
Equity in income related to subsidiaries			356,620	303,212
Investment gains			0	0
Investment losses			0	0
Changes in operating assets and liabilities:
Restricted cash			0	0
Tenant receivables			0	0
Deferred leasing costs			0	0
Other assets			0	0
Intercompany receivables and payables				0
Accounts payable, accrued expenses, and tenant security deposits			0	0
Net cash (used in) provided by operating activities			0	0
Investing Activities
Proceeds from sale of properties			0	0
Additions to properties			0	0
Purchase of properties			0	0
Payments for (Proceeds from) Deposits on Real Estate Acquisitions			0
Change in restricted cash related to construction projects			0	0
Contributions to unconsolidated real estate entity			0	0
Investments in subsidiaries			625,678	300,045
Additions to investments			0	0
Proceeds from investments			0	0
Proceeds from Collection of Notes Receivable			0
Net cash (used in) provided by investing activities			625,678	300,045
Financing Activities
Borrowings from secured notes payable			0	0
Repayments of borrowings from secured notes payable			0	0
Proceeds from Issuance of Unsecured Debt			0	0
Principal borrowings from unsecured senior line of credit			0	0
Repayments of borrowings from unsecured senior line of credit			0	0
Repayments of Unsecured Debt			0	0
Repayments of Convertible Debt				0
Transfers to/from parent company			(625,678)	(300,045)
Change in restricted cash related to financings			0	0
Deferred financing costs paid			0	0
Proceeds from Issuance of Common Stock				0
Dividends paid on common stock			0	0
Dividends paid on preferred stock			0	0
Proceeds from Noncontrolling Interests			0
Payments of Distributions to Affiliates			0
Distributions to noncontrolling interests			0	0
Net cash provided by (used in) financing activities			(625,678)	(300,045)
Effect of foreign exchange rate changes on cash and cash equivalents			0	0
Net increase in cash and cash equivalents			0	0
Cash and cash equivalents at beginning of period			0	0
Cash and cash equivalents at end of period	0	0	0	0
Supplemental Disclosure of Cash Flow Information
Cash paid during the period for interest, net of interest capitalized			0	0
Non-Cash Investing Activities
Note receivable from sale of real estate				0
Assumption of secured notes payable in connection with purchase of properties			$ 0