Subsequent events (Details) (Subsequent Event, Alexandria Center for Life Science-New York City)	Oct. 29, 2012 sqft
Subsequent Event \| Alexandria Center for Life Science-New York City
Subsequent event
Rentable square feet	309,141

The amount of rentable square feet related to real estate property.

No definition available.

Name:	are_RentableSquareFootageOfRealEstateProperty
Namespace Prefix:	are_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant