Fair Value of Financial Instruments (Details Textual)	Jun. 30, 2012
Maximum [Member]
Fair Value of Financial Instruments (Textual) [Abstract]
Rates of secured notes payable	8.40%
Minimum [Member]
Fair Value of Financial Instruments (Textual) [Abstract]
Rates of secured notes payable	3.90%

Rate used for discounted cash flow analysis of level two fair values of mortgages and notes payable.

No definition available.

Name:	aat_RateUsedForDiscountedCashFlowAnalysisOfLevelTwoFairValuesOfMortgagesAndNotesPayable
Namespace Prefix:	aat_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant