Commitments [Abstract]

No definition available.

Name:	are_CommitmentsAbstract
Namespace Prefix:	are_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Concentration of credit risk [Abstract]

+ References

No definition available.

+ Details

Name:	are_ConcentrationofcreditriskAbstract
Namespace Prefix:	are_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Limited Partnership Maximum Expiration Terms

+ References

No definition available.

+ Details

Name:	are_LimitedPartnershipMaximumExpirationTerms
Namespace Prefix:	are_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of largest tenants.

+ References

No definition available.

+ Details

Name:	are_NumberOfLargestTenant
Namespace Prefix:	are_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of leases held by the entity.

+ References

No definition available.

+ Details

Name:	are_NumberOfLeasesHeld
Namespace Prefix:	are_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of tenants.

+ References

No definition available.

+ Details

Name:	are_NumberOfTenants
Namespace Prefix:	are_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the expected period of payment obligation.

+ References

No definition available.

+ Details

Name:	are_PaymentObligationExpectedPeriod
Namespace Prefix:	are_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the remaining aggregate costs under contracts for the construction of properties undergoing development and redevelopment and generic life science laboratory infrastructure improvements contracts under the terms of leases.

+ References

No definition available.

+ Details

Name:	are_RemainingAggregateCostsUnderContracts
Namespace Prefix:	are_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_ConcentrationRiskLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e9054-108599

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6351-108592

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=123594938&loc=d3e13531-108611

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123594938&loc=d3e13537-108611

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

+ Details

Name:	us-gaap_ConcentrationRiskPercentage1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of contractual obligation, including but not limited to, long-term debt, capital lease obligations, operating lease obligations, purchase obligations, and other commitments.

+ References

No definition available.

+ Details

Name:	us-gaap_ContractualObligation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of cost for defined contribution plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 70
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942

+ Details

Name:	us-gaap_DefinedContributionPlanCostRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Remaining period of expected liquidation by investee of underlying asset of investment measured at net asset value per share or unit. In 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 6A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=SL6742756-110258

+ Details

Name:	us-gaap_FairValueInvestmentsEntitiesThatCalculateNetAssetValuePerShareLiquidatingInvestmentRemainingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of unfunded commitments for which the entity is obligated, to those certain investments for which net asset value per share is calculated (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 6A
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=SL6742756-110258

+ Details

Name:	us-gaap_FairValueInvestmentsEntitiesThatCalculateNetAssetValuePerShareUnfundedCommittments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_MajorCustomersAxis=are_ThreeLargestTenantsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConcentrationRiskByTypeAxis=are_LesseeConcentrationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConcentrationRiskByBenchmarkAxis=are_AnnualizedBaseRentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_MajorCustomersAxis=are_FirstLargestTenantMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_MajorCustomersAxis=are_SecondLargestTenantMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_MajorCustomersAxis=are_ThirdLargestTenantMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=are_LimitedpartnershipsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Commitments and contingencies (Details) $ in Millions	12 Months Ended
Commitments and contingencies (Details) $ in Millions	Dec. 31, 2021 USD ($) Tenant Lease	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Concentration Risk [Line Items]
Discretionary profit sharing contributions subject to statutory limitations	$ 5.0	$ 6.2	$ 4.9
Concentration of credit risk
Number of leases held \| Lease	1,201
Number of client tenants \| Tenant	893
Commitments
Remaining aggregate costs under contracts, under terms of leases	$ 2,800.0
Letters of credit and performance obligations	106.8
Investment commitments	$ 391.0
Limited Partnership Maximum Expiration Terms	11 years
Weighted-average remaining liquidation term (in years)	5 years 2 months 12 days
Minimum
Commitments
Expected period of payment obligation	1 year
Maximum
Commitments
Expected period of payment obligation	3 years
Three Largest Tenants \| Lessee Concentration \| Annualized Base Rent
Concentration of credit risk
Number of largest tenants	3
Concentration risk, percentage	8.30%
First Largest Tenant \| Lessee Concentration \| Annualized Base Rent
Concentration of credit risk
Concentration risk, percentage	3.00%
Second Largest Tenant \| Lessee Concentration \| Annualized Base Rent
Concentration of credit risk
Concentration risk, percentage	3.00%
Third Largest Tenant \| Lessee Concentration \| Annualized Base Rent
Concentration of credit risk
Concentration risk, percentage	2.30%
Investments in privately held entities that report NAV
Commitments
Investment commitments	$ 358.0
Weighted-average remaining liquidation term (in years)	9 years