Condensed Consolidating Financials - Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Operating Activities
Net income	$ 87,179	$ 60,547	$ 223,997	$ 202,065
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	134,437	118,852	268,524	233,071
Impairment of real estate	0	6,311	0	6,311
Loss on early extinguishment of debt	0	0	7,361	0
Equity in earnings of unconsolidated real estate JVs	(1,262)	(1,090)	(2,408)	(2,234)
Distributions of earnings from unconsolidated real estate joint ventures			1,679	287
Amortization of loan fees			4,613	5,136
Amortization of debt discounts (premiums)			(1,583)	(1,181)
Amortization of acquired below-market leases			(15,202)	(11,368)
Deferred rent			(52,441)	(55,890)
Stock compensation expense			22,466	15,223
Equity in earnings of affiliates	0	0	0	0
Investment income			(105,056)	(98,091)
Changes in operating assets and liabilities:
Tenant receivables			573	1,552
Deferred leasing costs			(23,471)	(29,705)
Other assets			560	(15,055)
Accounts payable, accrued expenses, and tenant security deposits			(21,272)	8,120
Net cash (used in) provided by operating activities			308,340	258,241
Investing Activities
Additions to real estate			(577,322)	(431,225)
Purchases of real estate			(715,030)	(688,698)
Deposits (paid) returned for investing activities			(9,000)	5,500
Investments in subsidiaries			0	0
Acquisition of interest in unconsolidated joint venture			0	(35,922)
Investments in unconsolidated real estate joint ventures			(95,950)	(44,486)
Additions to investments			(104,902)	(118,775)
Sales of investments			49,967	44,707
Net cash used in investing activities			(1,452,237)	(1,268,899)
Financing Activities
Borrowings from secured notes payable			0	9,044
Repayments of borrowings from secured notes payable			(302,878)	(3,162)
Proceeds from issuance of unsecured senior notes payable			854,209	899,321
Borrowings from unsecured senior line of credit			2,114,000	2,469,000
Repayments of borrowings from unsecured senior line of credit			(1,808,000)	(2,519,000)
Transfers to/from parent company			0	0
Payment of loan fees			(15,796)	(8,003)
Taxes paid related to net settlement of equity awards			(4,086)	0
Repurchase of Series D preferred stock			(9,240)	0
Proceeds from issuance of common stock			85,394	400,207
Dividends on common stock			(218,914)	(183,040)
Dividends on preferred stock			(2,132)	(2,604)
Contributions from and sales of noncontrolling interests			441,251	14,564
Distributions to and purchases of noncontrolling interests			(24,590)	(19,841)
Net cash provided by financing activities			1,109,218	1,056,486
Effect of foreign exchange rate changes on cash and cash equivalents			774	(1,173)
Net increase (decrease) in cash, cash equivalents, and restricted cash			(33,905)	44,655
Cash, cash equivalents, and restricted cash, beginning of period			272,130	277,186	$ 277,186
Cash, cash equivalents, and restricted cash, end of period	238,225	321,841	238,225	321,841	272,130
Supplemental Disclosures and Non-Cash Investing and Financing Activities:
Cash paid during the period for interest, net of interest capitalized			71,338	68,885
Non-Cash Investing Activities
Change in accrued construction			5,558	48,074
Accrued construction for current-period additions to real estate			181,922	183,573
Assumption of secured notes payable in connection with purchase of properties			(28,200)	0
Noncash, right-of-use asset			239,653	0
Noncash, lease liability			(245,638)	0
Eliminations
Operating Activities
Net income	(263,936)	(207,290)	(552,859)	(494,294)
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	0	0	0	0
Impairment of real estate		0		0
Loss on early extinguishment of debt			0
Equity in earnings of unconsolidated real estate JVs	0	0	0	0
Distributions of earnings from unconsolidated real estate joint ventures			0	0
Amortization of loan fees			0	0
Amortization of debt discounts (premiums)			0	0
Amortization of acquired below-market leases			0	0
Deferred rent			0	0
Stock compensation expense			0	0
Equity in earnings of affiliates	263,936	207,290	552,859	494,294
Investment income			0	0
Changes in operating assets and liabilities:
Tenant receivables			0	0
Deferred leasing costs			0	0
Other assets			0	0
Accounts payable, accrued expenses, and tenant security deposits			0	0
Net cash (used in) provided by operating activities			0	0
Investing Activities
Additions to real estate			0	0
Purchases of real estate			0	0
Deposits (paid) returned for investing activities			0	0
Investments in subsidiaries			2,269,492	1,865,964
Acquisition of interest in unconsolidated joint venture				0
Investments in unconsolidated real estate joint ventures			0	0
Additions to investments			0	0
Sales of investments			0	0
Net cash used in investing activities			2,269,492	1,865,964
Financing Activities
Borrowings from secured notes payable				0
Repayments of borrowings from secured notes payable			0	0
Proceeds from issuance of unsecured senior notes payable			0	0
Borrowings from unsecured senior line of credit			0	0
Repayments of borrowings from unsecured senior line of credit			0	0
Transfers to/from parent company			(2,269,492)	(1,865,964)
Payment of loan fees			0	0
Taxes paid related to net settlement of equity awards			0
Repurchase of Series D preferred stock			0
Proceeds from issuance of common stock			0	0
Dividends on common stock			0	0
Dividends on preferred stock			0	0
Contributions from and sales of noncontrolling interests			0	0
Distributions to and purchases of noncontrolling interests			0	0
Net cash provided by financing activities			(2,269,492)	(1,865,964)
Effect of foreign exchange rate changes on cash and cash equivalents			0	0
Net increase (decrease) in cash, cash equivalents, and restricted cash			0	0
Cash, cash equivalents, and restricted cash, beginning of period			0	0	0
Cash, cash equivalents, and restricted cash, end of period	0	0	0	0	0
Supplemental Disclosures and Non-Cash Investing and Financing Activities:
Cash paid during the period for interest, net of interest capitalized			0	0
Non-Cash Investing Activities
Change in accrued construction			0	0
Accrued construction for current-period additions to real estate			0	0
Assumption of secured notes payable in connection with purchase of properties			0
Noncash, right-of-use asset			0
Noncash, lease liability			0
Alexandria Real Estate Equities, Inc. (Issuer)
Operating Activities
Net income	78,767	54,730	207,926	190,360
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	1,752	1,647	3,415	3,324
Impairment of real estate		0		0
Loss on early extinguishment of debt			0
Equity in earnings of unconsolidated real estate JVs	0	0	0	0
Distributions of earnings from unconsolidated real estate joint ventures			0	0
Amortization of loan fees			4,412	4,260
Amortization of debt discounts (premiums)			(17)	378
Amortization of acquired below-market leases			0	0
Deferred rent			0	0
Stock compensation expense			22,466	15,223
Equity in earnings of affiliates	(142,651)	(106,552)	(328,618)	(292,720)
Investment income			0	43
Changes in operating assets and liabilities:
Tenant receivables			0	0
Deferred leasing costs			0	0
Other assets			(462)	(10,894)
Accounts payable, accrued expenses, and tenant security deposits			1,239	(726)
Net cash (used in) provided by operating activities			(89,639)	(90,752)
Investing Activities
Additions to real estate			0	0
Purchases of real estate			0	0
Deposits (paid) returned for investing activities			0	0
Investments in subsidiaries			(1,155,762)	(1,010,580)
Acquisition of interest in unconsolidated joint venture				0
Investments in unconsolidated real estate joint ventures			0	0
Additions to investments			0	0
Sales of investments			0	0
Net cash used in investing activities			(1,155,762)	(1,010,580)
Financing Activities
Borrowings from secured notes payable				0
Repayments of borrowings from secured notes payable			0	0
Proceeds from issuance of unsecured senior notes payable			854,209	899,321
Borrowings from unsecured senior line of credit			2,114,000	2,469,000
Repayments of borrowings from unsecured senior line of credit			(1,808,000)	(2,519,000)
Transfers to/from parent company			213,388	96,432
Payment of loan fees			(8,714)	(8,003)
Taxes paid related to net settlement of equity awards			(4,086)
Repurchase of Series D preferred stock			(9,240)
Proceeds from issuance of common stock			85,394	400,207
Dividends on common stock			(218,914)	(183,040)
Dividends on preferred stock			(2,132)	(2,604)
Contributions from and sales of noncontrolling interests			0	0
Distributions to and purchases of noncontrolling interests			0	0
Net cash provided by financing activities			1,215,905	1,152,313
Effect of foreign exchange rate changes on cash and cash equivalents			0	0
Net increase (decrease) in cash, cash equivalents, and restricted cash			(29,496)	50,981
Cash, cash equivalents, and restricted cash, beginning of period			119,305	130,516	130,516
Cash, cash equivalents, and restricted cash, end of period	89,809	181,497	89,809	181,497	119,305
Supplemental Disclosures and Non-Cash Investing and Financing Activities:
Cash paid during the period for interest, net of interest capitalized			63,970	56,392
Non-Cash Investing Activities
Change in accrued construction			0	0
Accrued construction for current-period additions to real estate			0	0
Assumption of secured notes payable in connection with purchase of properties			0
Noncash, right-of-use asset			0
Noncash, lease liability			0
Alexandria Real Estate Equities, L.P. (Guarantor Subsidiary)
Operating Activities
Net income	118,918	98,698	220,031	198,053
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	0	0	0	0
Impairment of real estate		0		0
Loss on early extinguishment of debt			0
Equity in earnings of unconsolidated real estate JVs	0	0	0	0
Distributions of earnings from unconsolidated real estate joint ventures			0	0
Amortization of loan fees			0	0
Amortization of debt discounts (premiums)			0	0
Amortization of acquired below-market leases			0	0
Deferred rent			0	0
Stock compensation expense			0	0
Equity in earnings of affiliates	(118,947)	(98,795)	(219,918)	(197,677)
Investment income			(113)	(375)
Changes in operating assets and liabilities:
Tenant receivables			0	0
Deferred leasing costs			0	0
Other assets			0	0
Accounts payable, accrued expenses, and tenant security deposits			0	(2)
Net cash (used in) provided by operating activities			0	(1)
Investing Activities
Additions to real estate			0	0
Purchases of real estate			0	0
Deposits (paid) returned for investing activities			0	0
Investments in subsidiaries			(1,091,328)	(838,102)
Acquisition of interest in unconsolidated joint venture				0
Investments in unconsolidated real estate joint ventures			0	0
Additions to investments			0	0
Sales of investments			172	377
Net cash used in investing activities			(1,091,156)	(837,725)
Financing Activities
Borrowings from secured notes payable				0
Repayments of borrowings from secured notes payable			0	0
Proceeds from issuance of unsecured senior notes payable			0	0
Borrowings from unsecured senior line of credit			0	0
Repayments of borrowings from unsecured senior line of credit			0	0
Transfers to/from parent company			1,091,156	837,717
Payment of loan fees			0	0
Taxes paid related to net settlement of equity awards			0
Repurchase of Series D preferred stock			0
Proceeds from issuance of common stock			0	0
Dividends on common stock			0	0
Dividends on preferred stock			0	0
Contributions from and sales of noncontrolling interests			0	0
Distributions to and purchases of noncontrolling interests			0	0
Net cash provided by financing activities			1,091,156	837,717
Effect of foreign exchange rate changes on cash and cash equivalents			0	0
Net increase (decrease) in cash, cash equivalents, and restricted cash			0	(9)
Cash, cash equivalents, and restricted cash, beginning of period			0	9	9
Cash, cash equivalents, and restricted cash, end of period	0	0	0	0	0
Supplemental Disclosures and Non-Cash Investing and Financing Activities:
Cash paid during the period for interest, net of interest capitalized			0	0
Non-Cash Investing Activities
Change in accrued construction			0	0
Accrued construction for current-period additions to real estate			0	0
Assumption of secured notes payable in connection with purchase of properties			0
Noncash, right-of-use asset			0
Noncash, lease liability			0
Combined Non- Guarantor Subsidiaries
Operating Activities
Net income	153,430	114,409	348,899	307,946
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	132,685	117,205	265,109	229,747
Impairment of real estate		6,311		6,311
Loss on early extinguishment of debt			7,361
Equity in earnings of unconsolidated real estate JVs	(1,262)	(1,090)	(2,408)	(2,234)
Distributions of earnings from unconsolidated real estate joint ventures			1,679	287
Amortization of loan fees			201	876
Amortization of debt discounts (premiums)			(1,566)	(1,559)
Amortization of acquired below-market leases			(15,202)	(11,368)
Deferred rent			(52,441)	(55,890)
Stock compensation expense			0	0
Equity in earnings of affiliates	(2,338)	(1,943)	(4,323)	(3,897)
Investment income			(104,943)	(97,759)
Changes in operating assets and liabilities:
Tenant receivables			573	1,552
Deferred leasing costs			(23,471)	(29,705)
Other assets			1,022	(4,161)
Accounts payable, accrued expenses, and tenant security deposits			(22,511)	8,848
Net cash (used in) provided by operating activities			397,979	348,994
Investing Activities
Additions to real estate			(577,322)	(431,225)
Purchases of real estate			(715,030)	(688,698)
Deposits (paid) returned for investing activities			(9,000)	5,500
Investments in subsidiaries			(22,402)	(17,282)
Acquisition of interest in unconsolidated joint venture				(35,922)
Investments in unconsolidated real estate joint ventures			(95,950)	(44,486)
Additions to investments			(104,902)	(118,775)
Sales of investments			49,795	44,330
Net cash used in investing activities			(1,474,811)	(1,286,558)
Financing Activities
Borrowings from secured notes payable				9,044
Repayments of borrowings from secured notes payable			(302,878)	(3,162)
Proceeds from issuance of unsecured senior notes payable			0	0
Borrowings from unsecured senior line of credit			0	0
Repayments of borrowings from unsecured senior line of credit			0	0
Transfers to/from parent company			964,948	931,815
Payment of loan fees			(7,082)	0
Taxes paid related to net settlement of equity awards			0
Repurchase of Series D preferred stock			0
Proceeds from issuance of common stock			0	0
Dividends on common stock			0	0
Dividends on preferred stock			0	0
Contributions from and sales of noncontrolling interests			441,251	14,564
Distributions to and purchases of noncontrolling interests			(24,590)	(19,841)
Net cash provided by financing activities			1,071,649	932,420
Effect of foreign exchange rate changes on cash and cash equivalents			774	(1,173)
Net increase (decrease) in cash, cash equivalents, and restricted cash			(4,409)	(6,317)
Cash, cash equivalents, and restricted cash, beginning of period			152,825	146,661	146,661
Cash, cash equivalents, and restricted cash, end of period	$ 148,416	$ 140,344	148,416	140,344	$ 152,825
Supplemental Disclosures and Non-Cash Investing and Financing Activities:
Cash paid during the period for interest, net of interest capitalized			7,368	12,493
Non-Cash Investing Activities
Change in accrued construction			5,558	48,074
Accrued construction for current-period additions to real estate			181,922	$ 183,573
Assumption of secured notes payable in connection with purchase of properties			(28,200)
Noncash, right-of-use asset			239,653
Noncash, lease liability			$ (245,638)