Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
REVENUE:
Rental income	$ 309,537	$ 298,803		$ 279,498
Other property income	21,330	16,180		15,590
Total revenue	330,867	314,983		295,088
EXPENSES:
Rental expenses	86,482	84,006		79,553
Real estate taxes	34,973	32,671		28,378
General and administrative	22,784	21,382		17,897
Depreciation and amortization	107,093	83,278		71,319
Total operating expenses	251,332	221,337		197,147
Operating income (loss)	79,535	93,646		97,941
Interest expense	(52,248)	(53,848)		(51,936)
Other income (expense), net	(85)	334		(368)
Net income	27,202	40,132		45,637
Net income attributable to restricted shares	(311)	(241)		(189)
Net income attributable to unitholders in the Operating Partnership	(7,205)	(10,814)		(12,863)
NET INCOME ATTRIBUTABLE TO AMERICAN ASSETS TRUST, INC. STOCKHOLDERS	$ 19,686	$ 29,077		$ 32,585
EARNINGS PER COMMON SHARE, BASIC
Basic net income attributable to common stockholders per share (in dollars per share)	$ 0.42	$ 0.62		$ 0.72
Weighted average shares of common stock outstanding-basic (in shares)	46,950,812	46,715,520		45,332,471
EARNINGS PER COMMON SHARE, DILUTED
Diluted net income attributable to common stockholders per share (in dollars per share)	$ 0.42	$ 0.62		$ 0.72
Weighted average shares of common stock outstanding-diluted (in shares)	64,136,559	64,087,250		63,228,159
COMPREHENSIVE INCOME
Net income	$ 27,202	$ 40,132		$ 45,637
Other comprehensive gain - unrealized gain on swap derivative during the period	120	386		17,048
Reclassification of amortization of forward starting swap included in interest expense	(1,279)	(1,114)		(231)
Comprehensive income	26,043	39,404		62,454
Comprehensive income attributable to noncontrolling interest	(6,877)	(10,433)		(17,624)
Comprehensive income attributable to American Assets Trust, Inc.	19,166	28,971		44,830
American Assets Trust, L.P.
REVENUE:
Rental income	309,537	298,803		279,498
Other property income	21,330	16,180		15,590
Total revenue	330,867	314,983		295,088
EXPENSES:
Rental expenses	86,482	84,006		79,553
Real estate taxes	34,973	32,671		28,378
General and administrative	22,784	21,382		17,897
Depreciation and amortization	107,093	83,278		71,319
Total operating expenses	251,332	221,337		197,147
Operating income (loss)	79,535	93,646		97,941
Interest expense	(52,248)	(53,848)		(51,936)
Other income (expense), net	(85)	334		(368)
Net income	27,202	40,132		45,637
Net income attributable to restricted shares	(311)	(241)		(189)
NET INCOME ATTRIBUTABLE TO AMERICAN ASSETS TRUST, INC. STOCKHOLDERS	$ 26,891	$ 39,891		$ 45,448
EARNINGS PER COMMON SHARE, BASIC
Basic net income attributable to common stockholders per share (in dollars per share)	$ 0.42	$ 0.62		$ 0.72
Weighted average shares of common stock outstanding-basic (in shares)	64,136,559	64,087,250		63,228,159
EARNINGS PER COMMON SHARE, DILUTED
Diluted net income attributable to common stockholders per share (in dollars per share)	$ 0.42	$ 0.62		$ 0.72
Weighted average shares of common stock outstanding-diluted (in shares)	64,136,559	64,087,250		63,228,159
DISTRIBUTIONS PER UNIT (in dollars per share)	$ 1.09	$ 1.05		$ 1.01
COMPREHENSIVE INCOME
Net income	$ 27,202	$ 40,132		$ 45,637
Other comprehensive gain - unrealized gain on swap derivative during the period	120	386		17,048
Reclassification of amortization of forward starting swap included in interest expense	(1,279)	(1,114)		(231)
Comprehensive income	26,043	39,404		62,454
American Assets Trust, L.P. | Limited Partner
EXPENSES:
Net income	7,205	10,814	[1]	12,863	[1]
COMPREHENSIVE INCOME
Net income	7,205	10,814	[1]	12,863	[1]
Comprehensive income attributable to American Assets Trust, Inc.	(6,877)	(10,433)		(17,624)
American Assets Trust, L.P. | General Partner
EXPENSES:
Net income	19,997	29,318	[2]	32,774	[2]
COMPREHENSIVE INCOME
Net income	19,997	29,318	[2]	32,774	[2]
Comprehensive income attributable to American Assets Trust, Inc.	19,166	28,971		44,830
Swap
COMPREHENSIVE INCOME
Other comprehensive gain - unrealized gain on swap derivative during the period	120	(10,281)		17,048
Swap | American Assets Trust, L.P.
COMPREHENSIVE INCOME
Other comprehensive gain - unrealized gain on swap derivative during the period	$ 120	(10,281)		$ 17,048
Forward Contracts
COMPREHENSIVE INCOME
Other comprehensive gain - unrealized gain on swap derivative during the period		10,667
Forward Contracts | American Assets Trust, L.P.
COMPREHENSIVE INCOME
Other comprehensive gain - unrealized gain on swap derivative during the period		$ 10,667

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

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