Secured and unsecured senior debt Summary of financial covenants (Details)	Dec. 31, 2014
Unsecured senior notes payable
Debt Instrument [Line Items]
Total Debt to Total Assets (as a percent)	60.00%
Secured Debt to Total Assets (as a percent)	40.00%
Debt Instrument, EBITDA to Interest Expense Ratio	150.00%
Unencumbered Total Asset Value to Unsecured Debt (as a percent)	150.00%
Unsecured bank debt
Debt Instrument [Line Items]
Secured Debt to Total Assets (as a percent)	45.00%
Maximum Ratio of Indebtedness to Total Assets Covenant Compliance	60.00%
Fixed charge coverage ratio	150.00%
Maximum Unsecured Leverage Ratio Covenant Compliance	60.00%
Minimum Unsecured Interest Coverage Ratio Covenant Compliance	1.50

Represents the EBITDA to interest expense ratio under the financial covenants related to debt instrument.

No definition available.

Name:	are_DebtInstrumentEBITDAToInterestExpenseRatio
Namespace Prefix:	are_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the ratio of secured debt to total assets under the debt instrument financial covenants.

+ References

No definition available.

+ Details

Name:	are_DebtInstrumentSecuredDebtToTotalAssetsRatio
Namespace Prefix:	are_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the ratio of unencumbered total asset value to total unsecured debt.

+ References

No definition available.

+ Details

Name:	are_DebtInstrumentUnencumberedTotalAssetValueRatio
Namespace Prefix:	are_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Fixed charge coverage ratio

+ References

No definition available.

+ Details

Name:	are_Fixedchargecoverageratio
Namespace Prefix:	are_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the maximum total debt to total assets ratio allowable under the financial covenants related to our unsecured line of credit and unsecured term loans.

+ References

No definition available.

+ Details

Name:	are_MaximumRatioOfIndebtednessToTotalAssetsCovenantCompliance
Namespace Prefix:	are_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the maximum unsecured leverage ratio allowable under the financial covenants related to our unsecured line of credit and unsecured term loans.

+ References

No definition available.

+ Details

Name:	are_MaximumUnsecuredLeverageRatioCovenantCompliance
Namespace Prefix:	are_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the minimum unsecured interest coverage ratio allowable under the financial covenants related to our unsecured line of credit and unsecured term loans.

+ References

No definition available.

+ Details

Name:	are_MinimumUnsecuredInterestCoverageRatioCovenantCompliance
Namespace Prefix:	are_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Total Aggregate Indebtedness divided by Total Assets

+ References

No definition available.

+ Details

Name:	are_RatioOfIndebtednessToTotalAssets
Namespace Prefix:	are_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

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

- Details

Name:	us-gaap_LongtermDebtTypeAxis=are_UnsecuredbankdebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=are_UnsecuredSeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: