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, 2013															40,512,563
Beginning balance at Dec. 31, 2013		$ 686,578													$ 405		$ 692,196	$ (44,090)	$ 0			$ 38,067
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		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)	$ 1,617	$ 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
Beginning balance (in shares) at Dec. 31, 2013				17,917,109		40,512,563	[2]
Beginning balance at Dec. 31, 2013			686,578	$ 38,067		$ 648,511	[2]	$ 0
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)	1,617	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													$ 0		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)	0	0							(184)			(54)
Reclassification of amortization of forward starting swap included in interest expense		(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)	0	0							(184)			$ (54)
Reclassification of amortization of forward starting swap included in interest expense			(231)					(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)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		45,637	45,637	12,863		$ 32,774	[2]											32,774				12,863
Common shares issued (in shares)															219,480
Common shares issued		9,640													$ 2		9,638
Conversion of operating partnership units (in shares)															10,694	10,694
Conversion of operating partnership units		0															(79)					79
Issuance of restricted stock (in shares)															148,110
Issuance of restricted stock		0													$ 1		(1)
Forfeiture of restricted stock (in shares)															(33,707)
Forfeiture of restricted stock		0													$ 0		0
Dividends declared and paid		(64,077)																(46,004)				(18,073)
Stock-based compensation		2,414															2,414
Shares withheld for employee taxes (in shares)						(20,187)	[2]								(20,187)
Shares withheld for employee taxes		(807)	(807)			$ (807)	[2]								$ 0		(807)
Other comprehensive income (loss) unrealized gain (loss) on derivatives								17,048	17,048	17,048		0	0							12,222		4,826
Reclassification of amortization of forward starting swap included in interest expense		(231)	(231)					(231)											(166)			(65)
Ending balance (in shares) at Dec. 31, 2016															45,732,109
Ending balance at Dec. 31, 2016		838,551													$ 457		874,597	(77,296)	$ 11,798			28,995
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income		45,637	45,637	$ 12,863		$ 32,774	[2]											$ 32,774				12,863
Contributions from American Assets Trust, Inc. (in shares)	[2]					219,480
Contributions from American Assets Trust, Inc.			9,640			$ 9,640	[2]
Conversion of operating partnership units (in shares)				(10,694)		10,694	[2]
Conversion of operating partnership units				$ 79		$ (79)	[2]
Issuance of restricted units (in shares)	[2]					148,110
Forfeiture of restricted units (in shares)	[2]					(33,707)
Distributions			(64,077)	$ (18,073)		$ (46,004)	[2]
Stock-based compensation			2,414			$ 2,414	[2]
Shares withheld for employee taxes (in shares)						(20,187)	[2]								(20,187)
Shares withheld for employee taxes		$ (807)	(807)			$ (807)	[2]								$ 0		$ (807)
Other comprehensive income (loss) unrealized gain (loss) on derivatives								17,048	$ 17,048	$ 17,048		$ 0	$ 0							$ 12,222		$ 4,826
Reclassification of amortization of forward starting swap included in interest expense			(231)
Ending balance (in shares) at Dec. 31, 2016				17,888,822		45,732,109	[2]
Ending balance at Dec. 31, 2016			$ 838,551	$ 24,315		$ 797,758	[2]	$ 16,478

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

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