Consolidated Statements of Equity - USD ($) $ in Thousands		Total	Swap	Forward Contracts	Early Extinguishment of Debt	Interest Expense	American Assets Trust, L.P.	American Assets Trust, L.P. Swap	American Assets Trust, L.P. Forward Contracts	American Assets Trust, L.P. Early Extinguishment of Debt	American Assets Trust, L.P. Interest Expense	Limited Partner American Assets Trust, L.P.	[1]	General Partner American Assets Trust, L.P.		Accumulated Other Comprehensive Income (Loss) American Assets Trust, L.P.	Accumulated Other Comprehensive Income (Loss) American Assets Trust, L.P. Swap	Accumulated Other Comprehensive Income (Loss) American Assets Trust, L.P. Forward Contracts	Accumulated Other Comprehensive Income (Loss) American Assets Trust, L.P. Early Extinguishment of Debt	Accumulated Other Comprehensive Income (Loss) American Assets Trust, L.P. Interest Expense	Common Stock	Common Stock American Assets Trust, L.P.	Additional Paid-in Capital	Accumulated dividends in excess of net income	Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) Swap	Accumulated Other Comprehensive Income (Loss) Forward Contracts	Accumulated Other Comprehensive Income (Loss) Early Extinguishment of Debt	Accumulated Other Comprehensive Income (Loss) Interest Expense	Noncontrolling Interests - Unitholders in the Operating Partnership	Noncontrolling Interests - Unitholders in the Operating Partnership Swap	Noncontrolling Interests - Unitholders in the Operating Partnership Forward Contracts	Noncontrolling Interests - Unitholders in the Operating Partnership Early Extinguishment of Debt	Noncontrolling Interests - Unitholders in the Operating Partnership Interest Expense
Beginning balance (in shares) at Dec. 31, 2018																					47,335,409
Beginning balance at Dec. 31, 2018		$ 802,471																			$ 474		$ 920,661	$ (128,778)	$ 10,620					$ (506)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		60,188					$ 60,188					$ 14,089		$ 46,099	[2]									46,099						14,089
Common shares issued (in shares)																					11,871,552
Common shares issued		515,354																			$ 118		515,236
Issuance of restricted stock (in shares)																					173,008
Issuance of restricted stock		0																			$ 2		(2)
Forfeiture of restricted stock (in shares)																					(70,641)
Forfeiture of restricted stock		0																			$ (1)		1
Conversion of operating partnership units (in shares)																					787,060	787,060
Conversion of operating partnership units		0																			$ 8		12,979		148					(13,135)
Dividends declared and paid		(80,605)																						(61,699)
Dividends declared and paid (noncontrolling interest)																														18,906
Stock-based compensation		4,477																					4,477
Shares withheld for employee taxes (in shares)														(28,160)	[2]						(28,160)
Shares withheld for employee taxes		(1,338)					(1,338)							$ (1,338)	[2]						$ 0		(1,338)
Other comprehensive gain (loss) - unrealized gain (loss) on swap derivatives during the period		(5,571)	$ (6,084)	$ 513			(5,571)	$ (6,084)	$ 513								$ (6,084)	$ 513								$ (4,482)	$ 392				$ (1,602)	$ 121
Reclassification of amortization of forward starting swaps included in interest expense					$ 0	$ (1,304)				$ 0	$ (1,304)									$ (1,304)									$ (998)					$ (306)
Ending balance (in shares) at Dec. 31, 2019																					60,068,228
Ending balance at Dec. 31, 2019		1,293,672																			$ 601		1,452,014	(144,378)	5,680					(20,245)
Beginning balance (in shares) at Dec. 31, 2018												17,177,608		47,335,409	[2]
Beginning balance at Dec. 31, 2018							802,471					$ (4,477)		$ 792,357	[2]	$ 14,591
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income		60,188					60,188					$ 14,089		$ 46,099	[2]									46,099						14,089
Contributions from American Assets Trust, Inc. (in shares)	[2]													11,871,552
Contributions from American Assets Trust, Inc.							515,354							$ 515,354	[2]
Conversion of operating partnership units (in shares)												(787,060)		787,060	[2]
Conversion of operating partnership units												$ (12,987)		$ 12,987	[2]
Issuance of restricted units (in shares)	[2]													173,008
Forfeiture of restricted units (in shares)	[2]													(70,641)
Distributions							(80,605)					$ (18,906)		$ (61,699)	[2]
Stock-based compensation							4,477							$ 4,477	[2]
Shares withheld for employee taxes (in shares)														(28,160)	[2]						(28,160)
Units withheld for employee taxes		(1,338)					(1,338)							$ (1,338)	[2]						$ 0		(1,338)
Other comprehensive gain (loss) - unrealized gain (loss) on swap derivatives during the period		(5,571)	(6,084)	$ 513			(5,571)	(6,084)	$ 513								(6,084)	$ 513								(4,482)	$ 392				(1,602)	$ 121
Reclassification of amortization of forward starting swaps included in interest expense					0	(1,304)				0	(1,304)									(1,304)									(998)					(306)
Ending balance (in shares) at Dec. 31, 2019												16,390,548		60,068,228	[2]
Ending balance at Dec. 31, 2019							1,293,672					$ (22,281)		$ 1,308,237	[2]	7,716
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		35,588					35,588					7,545		$ 28,043	[2]									28,043						7,545
Issuance of restricted stock (in shares)																					317,574
Issuance of restricted stock		0																			$ 3		(3)
Forfeiture of restricted stock (in shares)																					(95,086)
Forfeiture of restricted stock		0																			$ (1)		1
Conversion of operating partnership units (in shares)																					209,011	209,011
Conversion of operating partnership units		0																			$ 2		(12,003)		3					11,998
Dividends declared and paid		(76,510)																						(60,225)
Dividends declared and paid (noncontrolling interest)																														16,285
Stock-based compensation		6,307																					6,307
Shares withheld for employee taxes (in shares)														(23,435)	[2]						(23,435)
Shares withheld for employee taxes		(672)					(672)							$ (672)	[2]						$ 0		(672)
Other comprehensive gain (loss) - unrealized gain (loss) on swap derivatives during the period		(3,649)	(3,649)				(3,649)	(3,649)									(3,649)									(2,885)					(764)
Reclassification of amortization of forward starting swaps included in interest expense					0	(1,330)				0	(1,330)									(1,330)									(1,045)					(285)
Ending balance (in shares) at Dec. 31, 2020																					60,476,292
Ending balance at Dec. 31, 2020		1,253,406																			$ 605		1,445,644	(176,560)	1,753					(18,036)
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income		35,588					35,588					$ 7,545		$ 28,043	[2]									28,043						7,545
Conversion of operating partnership units (in shares)												(209,011)		209,011	[2]
Conversion of operating partnership units												$ 12,001		$ (12,001)	[2]
Issuance of restricted units (in shares)	[2]													317,574
Forfeiture of restricted units (in shares)	[2]													(95,086)
Distributions							(76,510)					$ (16,285)		$ (60,225)	[2]
Stock-based compensation							6,307							$ 6,307	[2]
Shares withheld for employee taxes (in shares)														(23,435)	[2]						(23,435)
Units withheld for employee taxes		(672)					(672)							$ (672)	[2]						$ 0		(672)
Other comprehensive gain (loss) - unrealized gain (loss) on swap derivatives during the period		(3,649)	(3,649)				(3,649)	(3,649)									(3,649)									(2,885)					(764)
Reclassification of amortization of forward starting swaps included in interest expense					0	(1,330)				0	(1,330)									(1,330)									(1,045)					(285)
Ending balance (in shares) at Dec. 31, 2020												16,181,537		60,476,292	[2]
Ending balance at Dec. 31, 2020							1,253,406					$ (19,020)		$ 1,269,689	[2]	2,737
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		36,593					36,593					7,653		$ 28,940	[2]									28,940						7,653
Issuance of restricted stock (in shares)																					229,819
Issuance of restricted stock		0																			$ 2		(2)
Forfeiture of restricted stock (in shares)																					(155,390)
Forfeiture of restricted stock		0																			$ (2)		2
Conversion of operating partnership units (in shares)																						0
Dividends declared and paid		(88,936)																						(70,165)
Dividends declared and paid (noncontrolling interest)																														18,771
Stock-based compensation		8,493																					8,493
Shares withheld for employee taxes (in shares)														(25,141)	[2]						(25,141)
Shares withheld for employee taxes		(865)					(865)							$ (865)	[2]						$ 0		(865)
Other comprehensive gain (loss) - unrealized gain (loss) on swap derivatives during the period		2,723	2,723				2,723	2,723									2,723									2,135					588
Reclassification of amortization of forward starting swaps included in interest expense					(193)	(1,098)				(193)	(1,098)								$ (193)	(1,098)								$ (152)	(864)				$ (41)	(234)
Ending balance (in shares) at Dec. 31, 2021																					60,525,580
Ending balance at Dec. 31, 2021		1,210,123																			$ 605		1,453,272	(217,785)	$ 2,872					(28,841)
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income		36,593					36,593					7,653		$ 28,940	[2]									$ 28,940						$ 7,653
Issuance of restricted units (in shares)	[2]													229,819
Forfeiture of restricted units (in shares)	[2]													(155,390)
Distributions							(88,936)					$ (18,771)		$ (70,165)	[2]
Stock-based compensation							8,493							$ 8,493	[2]
Shares withheld for employee taxes (in shares)														(25,141)	[2]						(25,141)
Units withheld for employee taxes		(865)					(865)							$ (865)	[2]						$ 0		$ (865)
Other comprehensive gain (loss) - unrealized gain (loss) on swap derivatives during the period		$ 2,723	$ 2,723				2,723	$ 2,723									$ 2,723									$ 2,135					$ 588
Reclassification of amortization of forward starting swaps included in interest expense					$ (193)	$ (1,098)				$ (193)	$ (1,098)								$ (193)	$ (1,098)								$ (152)	$ (864)				$ (41)	$ (234)
Ending balance (in shares) at Dec. 31, 2021												16,181,537		60,525,580	[2]
Ending balance at Dec. 31, 2021							$ 1,210,123					$ (30,138)		$ 1,236,092	[2]	$ 4,169

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

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