Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
REVENUE:
Rental income		$ 360,208	$ 330,312	$ 343,865
Other property income		15,620	14,261	22,876
Total revenue		375,828	344,573	366,741
EXPENSES:
Rental expenses		86,980	79,178	91,967
Real estate taxes		42,794	41,941	40,013
General and administrative		29,879	26,581	24,871
Depreciation and amortization		116,306	108,292	96,205
Total operating expenses		275,959	255,992	253,056
Operating income (loss)		99,869	88,581	113,685
Interest expense		(58,587)	(53,440)	(54,008)
Loss on early extinguishment of debt		(4,271)	0	0
Gain on sale of real estate		0	0	633
Other (expense) income, net		(418)	447	(122)
Net income		36,593	35,588	60,188
Net income attributable to restricted shares		(564)	(383)	(381)
Net income attributable to unitholders in the Operating Partnership		(7,653)	(7,545)	(14,089)
NET INCOME ATTRIBUTABLE TO AMERICAN ASSETS TRUST, INC. STOCKHOLDERS		$ 28,376	$ 27,660	$ 45,718
EARNINGS PER COMMON SHARE, BASIC
Basic net income attributable to common stockholders per share (in dollars per share)		$ 0.47	$ 0.46	$ 0.84
Weighted average shares of common stock outstanding-basic (in shares)		59,990,740	59,806,309	54,110,949
EARNINGS PER COMMON SHARE, DILUTED
Diluted net income attributable to common stockholders per share (in dollars per share)		$ 0.47	$ 0.46	$ 0.84
Weighted average shares of common stock outstanding-diluted (in shares)		76,172,277	76,119,763	70,786,132
COMPREHENSIVE INCOME
Net income		$ 36,593	$ 35,588	$ 60,188
Other comprehensive gain (loss) - unrealized gain (loss) on swap derivatives during the period		2,723	(3,649)	(5,571)
Comprehensive income		38,025	30,609	53,313
Comprehensive income attributable to noncontrolling interest		(7,966)	(6,496)	(12,301)
Comprehensive income attributable to American Assets Trust, Inc.		30,059	24,113	41,012
Early Extinguishment of Debt
COMPREHENSIVE INCOME
Reclassification of amortization of forward starting swaps included in interest expense		(193)	0	0
Interest Expense
COMPREHENSIVE INCOME
Reclassification of amortization of forward starting swaps included in interest expense		(1,098)	(1,330)	(1,304)
American Assets Trust, L.P.
REVENUE:
Rental income		360,208	330,312	343,865
Other property income		15,620	14,261	22,876
Total revenue		375,828	344,573	366,741
EXPENSES:
Rental expenses		86,980	79,178	91,967
Real estate taxes		42,794	41,941	40,013
General and administrative		29,879	26,581	24,871
Depreciation and amortization		116,306	108,292	96,205
Total operating expenses		275,959	255,992	253,056
Operating income (loss)		99,869	88,581	113,685
Interest expense		(58,587)	(53,440)	(54,008)
Loss on early extinguishment of debt		(4,271)	0	0
Gain on sale of real estate		0	0	633
Other (expense) income, net		(418)	447	(122)
Net income		36,593	35,588	60,188
Net income attributable to restricted shares		(564)	(383)	(381)
NET INCOME ATTRIBUTABLE TO AMERICAN ASSETS TRUST, INC. STOCKHOLDERS		$ 36,029	$ 35,205	$ 59,807
EARNINGS PER COMMON SHARE, BASIC
Basic net income attributable to common stockholders per share (in dollars per share)		$ 0.47	$ 0.46	$ 0.84
Weighted average shares of common stock outstanding-basic (in shares)		76,172,277	76,119,763	70,786,132
EARNINGS PER COMMON SHARE, DILUTED
Diluted net income attributable to common stockholders per share (in dollars per share)		$ 0.47	$ 0.46	$ 0.84
Weighted average shares of common stock outstanding-diluted (in shares)		76,172,277	76,119,763	70,786,132
DISTRIBUTIONS PER UNIT (in dollars per share)		$ 1.16	$ 1.00	$ 1.14
COMPREHENSIVE INCOME
Net income		$ 36,593	$ 35,588	$ 60,188
Other comprehensive gain (loss) - unrealized gain (loss) on swap derivatives during the period		2,723	(3,649)	(5,571)
Comprehensive income		38,025	30,609	53,313
American Assets Trust, L.P. | Early Extinguishment of Debt
COMPREHENSIVE INCOME
Reclassification of amortization of forward starting swaps included in interest expense		(193)	0	0
American Assets Trust, L.P. | Early Extinguishment of Debt | Accumulated Other Comprehensive Income (Loss)
COMPREHENSIVE INCOME
Reclassification of amortization of forward starting swaps included in interest expense		(193)
American Assets Trust, L.P. | Interest Expense
COMPREHENSIVE INCOME
Reclassification of amortization of forward starting swaps included in interest expense		(1,098)	(1,330)	(1,304)
American Assets Trust, L.P. | Interest Expense | Accumulated Other Comprehensive Income (Loss)
COMPREHENSIVE INCOME
Reclassification of amortization of forward starting swaps included in interest expense		(1,098)	(1,330)	(1,304)
American Assets Trust, L.P. | Limited Partner
EXPENSES:
Net income	[1]	7,653	7,545	14,089
COMPREHENSIVE INCOME
Net income	[1]	7,653	7,545	14,089
Comprehensive income attributable to American Assets Trust, Inc.		(7,966)	(6,496)	(12,301)
American Assets Trust, L.P. | General Partner
EXPENSES:
Net income	[2]	28,940	28,043	46,099
COMPREHENSIVE INCOME
Net income	[2]	28,940	28,043	46,099
Comprehensive income attributable to American Assets Trust, Inc.		$ 30,059	$ 24,113	$ 41,012

[1] Consists of limited partnership interests held by third parties.

[2] Consists of general and limited partnership interests held by American Assets Trust, Inc.