Consolidated Statements of Equity - USD ($) $ in Thousands		Total	American Assets Trust, L.P.	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.	Swap	Swap American Assets Trust, L.P.	Swap Accumulated Other Comprehensive Income (Loss) American Assets Trust, L.P.	Forward Contracts	Forward Contracts American Assets Trust, L.P.	Forward Contracts Accumulated Other Comprehensive Income (Loss) American Assets Trust, L.P.	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	Noncontrolling Interests - Unitholders in the Operating Partnership	Noncontrolling Interests - Unitholders in the Operating Partnership Swap	Noncontrolling Interests - Unitholders in the Operating Partnership Forward Contracts
Beginning balance (in shares) at Dec. 31, 2012															39,664,212.000
Beginning balance at Dec. 31, 2012		$ 685,729													$ 397		$ 663,589	$ (25,625)	$ 0			$ 47,368
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		22,594	$ 22,594	$ 6,838		$ 15,756	[2]											15,756				6,838
Common shares issued (in shares)															741,452
Common shares issued		24,910													$ 7		24,903
Conversion of operating partnership units (in shares)															106,326	106,326
Conversion of operating partnership units		0													$ 1		859					(860)
Issuance of restricted stock (in shares)															5,004
Issuance of restricted stock		0													$ 0
Forfeiture of restricted stock (in shares)															(4,431)
Forfeiture of restricted stock		0													$ 0
Dividends declared and paid		(49,500)																(34,221)				(15,279)
Stock-based compensation		2,845															2,845
Other comprehensive income (loss) unrealized gain (loss) on derivatives			0						$ 0			$ 0	$ 0
Reclassification of amortization of forward starting swap included in interest expense		0	0
Ending balance (in shares) at Dec. 31, 2013															40,512,563
Ending balance at Dec. 31, 2013		686,578													$ 405		692,196	(44,090)	0			38,067
Beginning balance (in shares) at Dec. 31, 2012				18,023,435		39,664,212	[2]
Beginning balance at Dec. 31, 2012			685,729	$ 47,368		$ 638,361	[2]	$ 0
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income		22,594	22,594	$ 6,838		$ 15,756	[2]											15,756				6,838
Contributions from American Assets Trust, Inc. (in shares)	[2]					741,452
Contributions from American Assets Trust, Inc.			24,910			$ 24,910	[2]
Conversion of operating partnership units (in shares)				(106,326)		106,326	[2]
Conversion of operating partnership units				$ (860)		$ 860	[2]
Issuance of restricted units (in shares)	[2]					5,004
Forfeiture of restricted units (in shares)	[2]					(4,431)
Distributions			(49,500)	$ (15,279)		$ (34,221)	[2]
Stock-based compensation			2,845			$ 2,845	[2]
Other comprehensive income (loss) unrealized gain (loss) on derivatives			0						0			0	0
Ending balance (in shares) at Dec. 31, 2013				17,917,109		40,512,563	[2]
Ending balance at Dec. 31, 2013			686,578	$ 38,067		$ 648,511	[2]	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		31,145	31,145	9,015		$ 22,130	[2]											22,130				9,015
Common shares issued (in shares)															3,110,067
Common shares issued		104,148													$ 31		104,117
Conversion of operating partnership units (in shares)															11,852	11,852
Conversion of operating partnership units		0															(133)					133
Issuance of restricted stock (in shares)															216,748
Issuance of restricted stock		0													$ 2		(2)
Forfeiture of restricted stock (in shares)															(1,192)
Forfeiture of restricted stock		0													$ 0
Dividends declared and paid		(54,311)																(38,331)				(15,980)
Stock-based compensation		3,666															3,666
Shares withheld for employee taxes (in shares)						(148,369)	[2]								(148,369)
Shares withheld for employee taxes		(4,780)	(4,780)			$ (4,780)	[2]								$ (1)		(4,779)
Other comprehensive income (loss) unrealized gain (loss) on derivatives			(1,448)						(1,448)	$ (1,448)	$ (1,448)	1,617	1,617	$ 1,617						$ (1,024)	$ 1,144		$ (424)	$ 473
Reclassification of amortization of forward starting swap included in interest expense		(39)	(39)																(28)			(11)
Ending balance (in shares) at Dec. 31, 2014															43,701,669
Ending balance at Dec. 31, 2014		766,576													$ 437		795,065	(60,291)	92			31,273
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income		31,145	31,145	$ 9,015		$ 22,130	[2]											22,130				9,015
Contributions from American Assets Trust, Inc. (in shares)	[2]					3,110,067
Contributions from American Assets Trust, Inc.			104,148			$ 104,148	[2]
Conversion of operating partnership units (in shares)				(11,852)		11,852	[2]
Conversion of operating partnership units				$ 133		$ (133)	[2]
Issuance of restricted units (in shares)	[2]					216,748
Forfeiture of restricted units (in shares)	[2]					(1,192)
Distributions			(54,311)	$ (15,980)		$ (38,331)	[2]
Stock-based compensation			3,666			$ 3,666	[2]
Shares withheld for employee taxes (in shares)						(148,369)	[2]								(148,369)
Shares withheld for employee taxes		(4,780)	(4,780)			$ (4,780)	[2]								$ (1)		(4,779)
Other comprehensive income (loss) unrealized gain (loss) on derivatives			(1,448)						(1,448)	(1,448)	(1,448)	1,617	1,617	$ 1,617						$ (1,024)	$ 1,144		$ (424)	$ 473
Reclassification of amortization of forward starting swap included in interest expense			(39)					(39)
Ending balance (in shares) at Dec. 31, 2014				17,905,257		43,701,669	[2]
Ending balance at Dec. 31, 2014			766,576	$ 31,235		$ 735,211	[2]	130
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		53,915	53,915	15,238		$ 38,677	[2]											38,677				15,238
Common shares issued (in shares)															1,812,451
Common shares issued		72,836													$ 18		72,818
Conversion of operating partnership units (in shares)															5,741	5,741
Conversion of operating partnership units		0															67					(67)
Issuance of restricted stock (in shares)															98,354
Issuance of restricted stock		0													$ 1		(1)
Forfeiture of restricted stock (in shares)															(40,687)
Forfeiture of restricted stock		0
Dividends declared and paid		(59,412)																(42,452)				(16,960)
Stock-based compensation		2,877															2,877
Shares withheld for employee taxes (in shares)						(169,809)	[2]								(169,809)
Shares withheld for employee taxes		(7,396)	(7,396)			$ (7,396)	[2]								$ (2)		(7,394)
Other comprehensive income (loss) unrealized gain (loss) on derivatives			(238)						(238)	(238)	(238)	0	0						(184)			(54)
Reclassification of amortization of forward starting swap included in interest expense		(231)	(231)					(231)											(166)			(65)
Ending balance (in shares) at Dec. 31, 2015															45,407,719
Ending balance at Dec. 31, 2015		828,927													$ 454		863,432	(64,066)	(258)			29,365
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income		53,915	53,915	$ 15,238		$ 38,677	[2]											$ 38,677				15,238
Contributions from American Assets Trust, Inc. (in shares)	[2]					1,812,451
Contributions from American Assets Trust, Inc.			72,836			$ 72,836	[2]
Conversion of operating partnership units (in shares)				(5,741)		5,741	[2]
Conversion of operating partnership units				$ (67)		$ 67	[2]
Issuance of restricted units (in shares)	[2]					98,354
Forfeiture of restricted units (in shares)	[2]					(40,687)
Distributions			(59,412)	$ (16,960)		$ (42,452)	[2]
Stock-based compensation			2,877			$ 2,877	[2]
Shares withheld for employee taxes (in shares)						(169,809)	[2]								(169,809)
Shares withheld for employee taxes		$ (7,396)	(7,396)			$ (7,396)	[2]								$ (2)		$ (7,394)
Other comprehensive income (loss) unrealized gain (loss) on derivatives			(238)						$ (238)	$ (238)	$ (238)	$ 0	$ 0						$ (184)			$ (54)
Reclassification of amortization of forward starting swap included in interest expense			(231)
Ending balance (in shares) at Dec. 31, 2015				17,899,516		45,407,719	[2]
Ending balance at Dec. 31, 2015			$ 828,927	$ 29,446		$ 799,820	[2]	$ (339)

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

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