Condensed consolidating financial information Cash Flows (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Operating Activities
Net income	$ 36,116	$ 33,337	$ 76,865	$ 63,574
Depreciation, Depletion and Amortization			107,735	93,575
Adjustments to reconcile net income to net cash provided by operating activities:
Gains (Losses) on Extinguishment of Debt	0	560	0	560
Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes	(797)	(772)	(797)	(772)
Loss on sale of real estate	0	(219)	0	121
Amortization of loan fees and costs			5,304	4,813
Amortization of debt premiums/discounts			136	237
Amortization of above and below Market Leases			(1,434)	(1,660)
Deferred rent			(24,619)	(14,437)
Stock compensation expense			6,304	7,812
Equity in income related to subsidiaries			0	0
Investment gains	(2,185)	(2,220)	(6,225)	(2,666)
Investment losses	3,546	143	5,240	529
Changes in operating assets and liabilities:
Restricted cash			0	392
Tenant receivables			(735)	847
Deferred leasing costs			(17,452)	(23,109)
Other assets			(5,916)	6,110
Intercompany receivables and payables				0
Accounts payable, accrued expenses, and tenant security deposits			85	8,215
Net cash (used in) provided by operating activities			144,491	144,141
Investing Activities
Proceeds from sale of properties			17,868	101,815
Additions to properties			(210,792)	(298,927)
Purchase of properties			(97,785)	0
Change in restricted cash related to construction projects			5,650	(8,889)
Contributions to unconsolidated real estate entity			(1,405)	(4,889)
Gain (Loss) on Investments			0	(293)
Investments in subsidiaries			0	0
Additions to investments			(25,358)	(14,833)
Proceeds from investments			8,794	9,544
Proceeds from Collection of Notes Receivable			29,851	0
Net cash (used in) provided by investing activities			(273,177)	(216,472)
Financing Activities
Borrowings from secured notes payable			77,762	26,114
Repayments of borrowings from secured notes payable			(219,427)	(31,436)
Proceeds from Issuance of Unsecured Debt			0	495,310
Principal borrowings from unsecured senior line of credit			637,000	305,000
Repayments of borrowings from unsecured senior line of credit			(270,000)	(871,000)
Repayments of Unsecured Debt			0	(150,000)
Transfers to/from parent company			0	0
Change in restricted cash related to financings			1,212	16,634
Deferred financing costs paid			(310)	(1,457)
Proceeds from Issuance of Common Stock			0	534,469
Dividends paid on common stock			(98,867)	(73,932)
Dividends paid on preferred stock			(12,943)	(12,942)
Proceeds from Noncontrolling Interests			19,410	0
Payments of Distributions to Affiliates			(595)	(596)
Distributions to noncontrolling interests			(1,388)	(639)
Net cash provided by (used in) financing activities			131,854	235,525
Effect of foreign exchange rate changes on cash and cash equivalents			837	(1,960)
Net increase in cash and cash equivalents			4,005	161,234
Cash and cash equivalents at beginning of period			57,696	140,971
Cash and cash equivalents at end of period	61,701	302,205	61,701	302,205
Supplemental Disclosure of Cash Flow Information
Cash paid during the period for interest, net of interest capitalized			31,922	29,259
Non-Cash Investing Activities
Note receivable from sale of real estate			0	38,820
Change in accrued capital expenditures			592	(48,198)
Assumption of secured notes payable in connection with purchase of properties			(48,329)	0
Alexandria Real Estate Equities, Inc. (Issuer)
Operating Activities
Net income	34,809	32,357	74,363	61,612
Depreciation, Depletion and Amortization			2,927	2,921
Adjustments to reconcile net income to net cash provided by operating activities:
Gains (Losses) on Extinguishment of Debt		560		560
Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes	0	0	0	0
Loss on sale of real estate				0
Amortization of loan fees and costs			3,542	3,381
Amortization of debt premiums/discounts			80	31
Amortization of above and below Market Leases			0	0
Deferred rent			0	0
Stock compensation expense			6,304	7,812
Equity in income related to subsidiaries			(119,860)	(103,719)
Investment gains			0	0
Investment losses			0	0
Changes in operating assets and liabilities:
Restricted cash			(9)	10
Tenant receivables			0	1
Deferred leasing costs			0	(792)
Other assets			(4,264)	31,434
Intercompany receivables and payables				(40)
Accounts payable, accrued expenses, and tenant security deposits			20,850	(20,871)
Net cash (used in) provided by operating activities			(16,067)	(17,660)
Investing Activities
Proceeds from sale of properties			0	10,796
Additions to properties			0	0
Purchase of properties			0
Change in restricted cash related to construction projects			0	0
Contributions to unconsolidated real estate entity			0	0
Gain (Loss) on Investments				0
Investments in subsidiaries			(235,931)	(61,214)
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			(235,931)	(50,418)
Financing Activities
Borrowings from secured notes payable			0	0
Repayments of borrowings from secured notes payable			0	0
Proceeds from Issuance of Unsecured Debt				495,310
Principal borrowings from unsecured senior line of credit			637,000	305,000
Repayments of borrowings from unsecured senior line of credit			(270,000)	(871,000)
Repayments of Unsecured Debt				(150,000)
Transfers to/from parent company			103	0
Change in restricted cash related to financings			0	0
Deferred financing costs paid			(44)	(1,095)
Proceeds from Issuance of Common Stock				534,469
Dividends paid on common stock			(98,867)	(73,932)
Dividends paid on preferred stock			(12,943)	(12,942)
Proceeds from Noncontrolling Interests			0
Payments of Distributions to Affiliates			0	0
Distributions to noncontrolling interests			0	0
Net cash provided by (used in) financing activities			255,249	225,810
Effect of foreign exchange rate changes on cash and cash equivalents			0	0
Net increase in cash and cash equivalents			3,251	157,732
Cash and cash equivalents at beginning of period			14,790	98,567
Cash and cash equivalents at end of period	18,041	256,299	18,041	256,299
Supplemental Disclosure of Cash Flow Information
Cash paid during the period for interest, net of interest capitalized			22,218	17,969
Non-Cash Investing Activities
Note receivable from sale of real estate				29,820
Change in accrued capital expenditures			0	0
Assumption of secured notes payable in connection with purchase of properties			0
Alexandria Real Estate Equities, L.P. (Guarantor Subsidiary)
Operating Activities
Net income	54,767	48,869	113,073	96,042
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
Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes	0	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			(114,608)	(96,183)
Investment gains			0	(152)
Investment losses			1,535	297
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
Change in restricted cash related to construction projects			0	0
Contributions to unconsolidated real estate entity			0	0
Gain (Loss) on Investments				0
Investments in subsidiaries			(205,546)	(88,247)
Additions to investments			0	100
Proceeds from investments			0	641
Proceeds from Collection of Notes Receivable			0
Net cash (used in) provided by investing activities			(205,546)	(87,506)
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
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
Transfers to/from parent company			205,546	85,589
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	0
Distributions to noncontrolling interests			0	0
Net cash provided by (used in) financing activities			205,546	85,589
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
Change in accrued capital expenditures			0	0
Assumption of secured notes payable in connection with purchase of properties			0
Combined Non- Guarantor Subsidiaries
Operating Activities
Net income	61,278	55,906	126,126	107,721
Depreciation, Depletion and Amortization			104,808	90,654
Adjustments to reconcile net income to net cash provided by operating activities:
Gains (Losses) on Extinguishment of Debt		0		0
Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes	(797)	(772)	(797)	(772)
Loss on sale of real estate				121
Amortization of loan fees and costs			1,762	1,432
Amortization of debt premiums/discounts			56	206
Amortization of above and below Market Leases			(1,434)	(1,660)
Deferred rent			(24,619)	(14,437)
Stock compensation expense			0	0
Equity in income related to subsidiaries			(2,229)	(1,899)
Investment gains			(6,225)	(2,514)
Investment losses			3,705	232
Changes in operating assets and liabilities:
Restricted cash			9	382
Tenant receivables			(735)	846
Deferred leasing costs			(17,452)	(22,317)
Other assets			(1,652)	(25,512)
Intercompany receivables and payables				40
Accounts payable, accrued expenses, and tenant security deposits			(20,765)	29,274
Net cash (used in) provided by operating activities			160,558	161,797
Investing Activities
Proceeds from sale of properties			17,868	91,019
Additions to properties			(210,792)	(298,927)
Purchase of properties			(97,785)
Change in restricted cash related to construction projects			5,650	(8,889)
Contributions to unconsolidated real estate entity			(1,405)	(4,889)
Gain (Loss) on Investments				(293)
Investments in subsidiaries			(8,095)	(1,243)
Additions to investments			(25,358)	(14,933)
Proceeds from investments			8,794	8,903
Proceeds from Collection of Notes Receivable			29,851
Net cash (used in) provided by investing activities			(281,272)	(229,252)
Financing Activities
Borrowings from secured notes payable			77,762	26,114
Repayments of borrowings from secured notes payable			(219,427)	(31,436)
Proceeds from Issuance of Unsecured Debt				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
Transfers to/from parent company			243,923	65,115
Change in restricted cash related to financings			1,212	16,634
Deferred financing costs paid			(266)	(362)
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			(595)	(596)
Distributions to noncontrolling interests			(1,388)	(639)
Net cash provided by (used in) financing activities			120,631	74,830
Effect of foreign exchange rate changes on cash and cash equivalents			837	(1,960)
Net increase in cash and cash equivalents			754	5,415
Cash and cash equivalents at beginning of period			42,906	40,491
Cash and cash equivalents at end of period	43,660	45,906	43,660	45,906
Supplemental Disclosure of Cash Flow Information
Cash paid during the period for interest, net of interest capitalized			9,704	11,290
Non-Cash Investing Activities
Note receivable from sale of real estate				9,000
Change in accrued capital expenditures			592	(48,198)
Assumption of secured notes payable in connection with purchase of properties			(48,329)
Eliminations
Operating Activities
Net income	(114,738)	(103,795)	(236,697)	(201,801)
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
Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes	0	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			236,697	201,801
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	188
Intercompany receivables and payables				0
Accounts payable, accrued expenses, and tenant security deposits			0	(188)
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
Change in restricted cash related to construction projects			0	0
Contributions to unconsolidated real estate entity			0	0
Gain (Loss) on Investments				0
Investments in subsidiaries			449,572	150,704
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			449,572	150,704
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
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
Transfers to/from parent company			(449,572)	(150,704)
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	0
Distributions to noncontrolling interests			0	0
Net cash provided by (used in) financing activities			(449,572)	(150,704)
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
Change in accrued capital expenditures			0	0
Assumption of secured notes payable in connection with purchase of properties			$ 0