Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
REVENUE:
Rental income		$ 261,887	$ 246,078	$ 242,757
Other property income		13,736	13,922	12,300
Total revenue		275,623	260,000	255,057
EXPENSES:
Rental expenses		73,187	68,267	68,608
Real estate taxes		24,819	22,964	21,378
General and administrative		20,074	18,532	17,195
Depreciation and amortization		63,392	66,568	66,775
Total operating expenses		181,472	176,331	173,956
Operating income (loss)		94,151	83,669	81,101
Interest expense		(47,260)	(52,965)	(58,020)
Gain on sale of real estate		7,121	0	0
Other income (expense), net		(97)	441	(487)
Net income		53,915	31,145	22,594
Net income attributable to restricted shares		(168)	(374)	(536)
Net income attributable to unitholders in the Operating Partnership		(15,238)	(9,015)	(6,838)
NET INCOME ATTRIBUTABLE TO AMERICAN ASSETS TRUST, INC. STOCKHOLDERS		$ 38,509	$ 21,756	$ 15,220
EARNINGS PER COMMON SHARE, BASIC
Basic net income attributable to common stockholders per share (in dollars per share)		$ 0.87	$ 0.52	$ 0.38
Weighted average shares of common stock outstanding-basic (in shares)		44,439,112	42,041,126	39,539,457
EARNINGS PER COMMON SHARE, DILUTED
Diluted net income attributable to common stockholders per share (in dollars per share)		$ 0.86	$ 0.51	$ 0.38
Weighted average shares of common stock outstanding-diluted (in shares)		62,339,163	59,947,474	57,515,810
COMPREHENSIVE INCOME
Net income		$ 53,915	$ 31,145	$ 22,594
Reclassification of amortization of forward starting swap included in interest expense		231	39	0
Comprehensive income		53,446	31,275	22,594
Comprehensive income attributable to non-controlling interest		(15,119)	(9,053)	(6,838)
Comprehensive income attributable to American Assets Trust, Inc.		38,327	22,222	15,756
American Assets Trust, L.P.
REVENUE:
Rental income		261,887	246,078	242,757
Other property income		13,736	13,922	12,300
Total revenue		275,623	260,000	255,057
EXPENSES:
Rental expenses		73,187	68,267	68,608
Real estate taxes		24,819	22,964	21,378
General and administrative		20,074	18,532	17,195
Depreciation and amortization		63,392	66,568	66,775
Total operating expenses		181,472	176,331	173,956
Operating income (loss)		94,151	83,669	81,101
Interest expense		(47,260)	(52,965)	(58,020)
Gain on sale of real estate		7,121	0	0
Other income (expense), net		(97)	441	(487)
Net income		53,915	31,145	22,594
Net income attributable to restricted shares		(168)	(374)	(536)
NET INCOME ATTRIBUTABLE TO AMERICAN ASSETS TRUST, INC. STOCKHOLDERS		$ 53,747	$ 30,771	$ 22,058
EARNINGS PER COMMON SHARE, BASIC
Basic net income attributable to common stockholders per share (in dollars per share)		$ 0.86	$ 0.51	$ 0.38
Weighted average shares of common stock outstanding-basic (in shares)		62,339,163	59,947,474	57,515,810
EARNINGS PER COMMON SHARE, DILUTED
Diluted net income attributable to common stockholders per share (in dollars per share)		$ 0.86	$ 0.51	$ 0.38
Weighted average shares of common stock outstanding-diluted (in shares)		62,339,163	59,947,474	57,515,810
DISTRIBUTIONS PER UNIT (in dollars per share)		$ 0.9475	$ 0.8925	$ 0.85
COMPREHENSIVE INCOME
Net income		$ 53,915	$ 31,145	$ 22,594
Other comprehensive loss - unrealized loss on swap derivative during the period		(238)	(1,448)	0
Reclassification of amortization of forward starting swap included in interest expense		231	39	0
Comprehensive income		53,446	31,275	22,594
American Assets Trust, L.P. | Limited Partner
EXPENSES:
Net income	[1]	15,238	9,015	6,838
COMPREHENSIVE INCOME
Net income	[1]	15,238	9,015	6,838
Comprehensive income attributable to American Assets Trust, Inc.		(15,119)	(9,053)	(6,838)
American Assets Trust, L.P. | General Partner
EXPENSES:
Net income	[2]	38,677	22,130	15,756
COMPREHENSIVE INCOME
Net income	[2]	38,677	22,130	15,756
Comprehensive income attributable to American Assets Trust, Inc.		38,327	22,222	15,756
Swap
COMPREHENSIVE INCOME
Other comprehensive loss - unrealized loss on swap derivative during the period		(238)	(1,448)	0
Swap | American Assets Trust, L.P.
COMPREHENSIVE INCOME
Other comprehensive loss - unrealized loss on swap derivative during the period		(238)	(1,448)
Forward Contracts
COMPREHENSIVE INCOME
Other comprehensive loss - unrealized loss on swap derivative during the period		0	1,617	0
Forward Contracts | American Assets Trust, L.P.
COMPREHENSIVE INCOME
Other comprehensive loss - unrealized loss on swap derivative during the period		$ 0	$ 1,617	$ 0

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

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