Component of Rental Income and Expense Components of Rental Income (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Rental Income [Line Items]
Cost reimbursement	$ 0	$ 34,584	$ 34,267
Percentage rent	2,476	3,149	3,214
Hotel revenue	40,297	40,049	39,545
Other	2,223	1,611	1,667
Total rental income	343,865	309,537	298,803
Total Retail
Rental Income [Line Items]
Minimum rents	99,601	77,147	76,201
Total Office
Rental Income [Line Items]
Minimum rents	136,118	95,081	93,128
Total Multifamily
Rental Income [Line Items]
Minimum rents	47,448	46,897	40,217
Total Mixed-Use
Rental Income [Line Items]
Minimum rents	$ 15,702	$ 11,019	$ 10,564

Other real estate rental revenue.

No definition available.

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Balance Type:	credit
Period Type:	duration

- Definition

Rental Income [Line Items]

+ References

No definition available.

+ Details

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- Definition

In accordance with the provisions of their lease agreement, this element represents allowable charges due a landlord from its tenant. In retail store and office building leases, for example, tenant reimbursements may cover items such as taxes, utilities, and common area expenses.

+ References

No definition available.

+ Details

Name:	aat_TenantReimbursementsLeaseRevenue
Namespace Prefix:	aat_
Data Type:	xbrli:monetaryItemType
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Period Type:	duration

- Definition

The total amount of revenue recognized for the period from operating leases, including minimum lease revenue, contingent revenue, percentage revenue and sublease revenue.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 25
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=77902458&loc=d3e39896-112707

+ Details

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- Definition

The total amount of lease revenue recognized for the period for which the lessee was obligated under leasing arrangements regardless of any other events or conditions. This amount excludes contingent revenue and sublease revenue.

+ References

+ Details

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- Definition

This element represents the rental revenue earned during the period from lessee-operators based on revenues generated in their operations, generally in excess of a base amount. Such rental revenue is generally stipulated in the lease agreement, usually will provide for a fixed percentage of revenue to be paid as additional (or possibly only) rent due the lessor, and may be based on gross revenues, net revenues, or multiple variations thereof. Percentage rent is often required under leases with retail outlets located on premises owned by hoteliers, cruise lines, others in the hospitality industry, and shopping mall operators, among others.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1(e))
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

+ Details

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- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

+ Details

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- Details

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- Details

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- Details

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- Details

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