Consolidated Statement of Equity (Unaudited) - 6 months ended Jun. 30, 2017 - USD ($) $ in Thousands		Total	American Assets Trust, L.P.	American Assets Trust, L.P. Accumulated Other Comprehensive Income (Loss)	American Assets Trust, L.P. Limited Partner	[1]	American Assets Trust, L.P. General Partner		Common Shares	Additional Paid-in Capital	Accumulated Dividends in Excess of Net Income	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests - Unitholders in the Operating Partnership	Swap	Swap American Assets Trust, L.P.	Swap American Assets Trust, L.P. Accumulated Other Comprehensive Income (Loss)	Swap Accumulated Other Comprehensive Income (Loss)	Swap Noncontrolling Interests - Unitholders in the Operating Partnership	Forward Contracts	Forward Contracts American Assets Trust, L.P.	Forward Contracts American Assets Trust, L.P. Accumulated Other Comprehensive Income (Loss)	Forward Contracts Accumulated Other Comprehensive Income (Loss)	Forward Contracts Noncontrolling Interests - Unitholders in the Operating Partnership
Beginning Balance (in shares) at Dec. 31, 2016									45,732,109
Beginning Balance at Dec. 31, 2016		$ 838,551							$ 457	$ 874,597	$ (77,296)	$ 11,798	$ 28,995
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		17,896	$ 17,896		$ 4,869		$ 13,027	[2]			13,027		4,869
Common shares issued (in shares)									700,000
Common shares issued		30,075							$ 7	30,068
Issuance of restricted stock (in shares)									4,880
Issuance of restricted stock		0							$ 0	0
Forfeiture of restricted stock (in shares)									(768)
Forfeiture of restricted stock		0							$ 0	0
Conversion of operating partnership units (in shares)									693,842
Conversion of operating partnership units		0							$ 7	10,752			(10,759)
Dividends declared and paid		(33,448)									(24,326)
Dividends declared and paid (noncontrolling interest)													(9,122)
Stock-based compensation		1,278								1,278
Other comprehensive loss - change in value of interest rate swaps		(1,514)	(1,514)											$ (12,181)	$ (12,181)	$ (12,181)	$ (8,704)	$ (3,477)	$ 10,667	$ 10,667	$ 10,667	$ 7,745	$ 2,922
Reclassification of amortization of forward-starting swap included in interest expense		(475)	(475)	$ (475)								(345)	(130)
Ending Balance (in shares) at Jun. 30, 2017									47,130,063
Ending Balance at Jun. 30, 2017		852,363							$ 471	$ 916,695	(88,595)	10,494	13,298
Beginning partners' capital account (in shares) at Dec. 31, 2016					17,888,822		45,732,109	[2]
Beginning partners' capital account at Dec. 31, 2016			838,551	16,478	$ 24,315		$ 797,758	[2]
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income		17,896	17,896		$ 4,869		$ 13,027	[2]			$ 13,027		4,869
Contributions from American Assets Trust, Inc. (in shares)	[2]						700,000
Contributions from American Assets Trust, Inc.			30,075				$ 30,075	[2]
Conversion of operating partnership units (in shares)					(693,842)		(693,842)	[2]
Conversion of operating partnership units					$ (10,759)		$ 10,759	[2]
Issuance of restricted units (in shares)	[2]						4,880
Forfeiture of restricted units (in shares)	[2]						(768)
Distributions			(33,448)		$ (9,122)		$ (24,326)	[2]
Stock-based compensation			1,278				$ 1,278	[2]
Other comprehensive (loss) - unrealized (loss) on swap derivative during the period		(1,514)	(1,514)											$ (12,181)	$ (12,181)	$ (12,181)	$ (8,704)	$ (3,477)	$ 10,667	$ 10,667	$ 10,667	$ 7,745	$ 2,922
Reclassification of amortization of forward-starting swap included in interest expense		$ (475)	(475)	(475)								$ (345)	$ (130)
Ending partners' capital account (in shares) at Jun. 30, 2017					17,194,980		47,130,063	[2]
Ending partners' capital account at Jun. 30, 2017			$ 852,363	$ 14,489	$ 9,303		$ 828,571	[2]

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

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