Segment Reporting Net Real Estate and Secured Note Payable Balances for Each Segment (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Net Real Estate		$ 1,831,546	$ 1,834,862
Secured Notes Payable	[1]	447,028	584,002
Capital Expenditures and Leasing Commissions	[2]	63,205	138,635
Total Retail
Segment Reporting Information [Line Items]
Net Real Estate		629,261	638,893
Secured Notes Payable	[1]	36,424	60,065
Capital Expenditures and Leasing Commissions	[2]	13,371	7,393
Total Office
Segment Reporting Information [Line Items]
Net Real Estate		813,414	796,773
Secured Notes Payable	[1]	206,550	292,183
Capital Expenditures and Leasing Commissions	[2]	46,476	49,049
Total Multifamily
Segment Reporting Information [Line Items]
Net Real Estate		203,014	208,730
Secured Notes Payable	[1]	73,744	101,444
Capital Expenditures and Leasing Commissions	[2]	2,463	81,559
Total Mixed-Use
Segment Reporting Information [Line Items]
Net Real Estate		185,857	190,466
Secured Notes Payable	[1]	130,310	130,310
Capital Expenditures and Leasing Commissions	[2]	895	634
American Assets Trust, L.P.
Segment Reporting Information [Line Items]
Net Real Estate		1,831,546	1,834,862
Secured notes payable | American Assets Trust, L.P.
Segment Reporting Information [Line Items]
Unamortized fair value adjustment and debt issuance costs		$ (1,800)	$ (5,000)

[1] Excludes unamortized fair market value adjustments and debt issuance costs of $1.8 million and $5.0 million as of December 31, 2016 and 2015, respectively.

[2] Capital expenditures represent cash paid for capital expenditures during the year and includes leasing commissions paid.