Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
REVENUE:
Rental income		$ 279,498	$ 261,887	$ 246,078
Other property income		15,590	13,736	13,922
Total revenue		295,088	275,623	260,000
EXPENSES:
Rental expenses		79,553	73,187	68,267
Real estate taxes		28,378	24,819	22,964
General and administrative		17,897	20,074	18,532
Depreciation and amortization		71,319	63,392	66,568
Total operating expenses		197,147	181,472	176,331
Operating income (loss)		97,941	94,151	83,669
Interest expense		(51,936)	(47,260)	(52,965)
Gain on sale of real estate		0	7,121	0
Other income (expense), net		(368)	(97)	441
Net income		45,637	53,915	31,145
Net income attributable to restricted shares		(189)	(168)	(374)
Net income attributable to unitholders in the Operating Partnership		(12,863)	(15,238)	(9,015)
NET INCOME ATTRIBUTABLE TO AMERICAN ASSETS TRUST, INC. STOCKHOLDERS		$ 32,585	$ 38,509	$ 21,756
EARNINGS PER COMMON SHARE, BASIC
Basic net income attributable to common stockholders per share (in dollars per share)		$ 0.72	$ 0.87	$ 0.52
Weighted average shares of common stock outstanding-basic (in shares)		45,332,471	44,439,112	42,041,126
EARNINGS PER COMMON SHARE, DILUTED
Diluted net income attributable to common stockholders per share (in dollars per share)		$ 0.72	$ 0.86	$ 0.51
Weighted average shares of common stock outstanding-diluted (in shares)		63,228,159	62,339,163	59,947,474
COMPREHENSIVE INCOME
Net income		$ 45,637	$ 53,915	$ 31,145
Reclassification of amortization of forward starting swap included in interest expense		(231)	(231)	(39)
Comprehensive income		62,454	53,446	31,275
Comprehensive income attributable to non-controlling interest		(17,624)	(15,119)	(9,053)
Comprehensive income attributable to American Assets Trust, Inc.		44,830	38,327	22,222
American Assets Trust, L.P.
REVENUE:
Rental income		279,498	261,887	246,078
Other property income		15,590	13,736	13,922
Total revenue		295,088	275,623	260,000
EXPENSES:
Rental expenses		79,553	73,187	68,267
Real estate taxes		28,378	24,819	22,964
General and administrative		17,897	20,074	18,532
Depreciation and amortization		71,319	63,392	66,568
Total operating expenses		197,147	181,472	176,331
Operating income (loss)		97,941	94,151	83,669
Interest expense		(51,936)	(47,260)	(52,965)
Gain on sale of real estate		0	7,121	0
Other income (expense), net		(368)	(97)	441
Net income		45,637	53,915	31,145
Net income attributable to restricted shares		(189)	(168)	(374)
NET INCOME ATTRIBUTABLE TO AMERICAN ASSETS TRUST, INC. STOCKHOLDERS		$ 45,448	$ 53,747	$ 30,771
EARNINGS PER COMMON SHARE, BASIC
Basic net income attributable to common stockholders per share (in dollars per share)		$ 0.72	$ 0.86	$ 0.51
Weighted average shares of common stock outstanding-basic (in shares)		63,228,159	62,339,163	59,947,474
EARNINGS PER COMMON SHARE, DILUTED
Diluted net income attributable to common stockholders per share (in dollars per share)		$ 0.72	$ 0.86	$ 0.51
Weighted average shares of common stock outstanding-diluted (in shares)		63,228,159	62,339,163	59,947,474
DISTRIBUTIONS PER UNIT (in dollars per share)		$ 1.01	$ 0.9475	$ 0.8925
COMPREHENSIVE INCOME
Net income		$ 45,637	$ 53,915	$ 31,145
Reclassification of amortization of forward starting swap included in interest expense		(231)	(231)	(39)
Comprehensive income		62,454	53,446	31,275
American Assets Trust, L.P. | Limited Partner
EXPENSES:
Net income	[1]	12,863	15,238	9,015
COMPREHENSIVE INCOME
Net income	[1]	12,863	15,238	9,015
Comprehensive income attributable to American Assets Trust, Inc.		(17,624)	(15,119)	(9,053)
American Assets Trust, L.P. | General Partner
EXPENSES:
Net income	[2]	32,774	38,677	22,130
COMPREHENSIVE INCOME
Net income	[2]	32,774	38,677	22,130
Comprehensive income attributable to American Assets Trust, Inc.		44,830	38,327	22,222
Swap
COMPREHENSIVE INCOME
Other comprehensive gain (loss) - unrealized gain (loss) on swap derivative during the period		17,048	(238)	(1,448)
Swap | American Assets Trust, L.P.
COMPREHENSIVE INCOME
Other comprehensive gain (loss) - unrealized gain (loss) on swap derivative during the period		17,048	(238)	(1,448)
Forward Contracts
COMPREHENSIVE INCOME
Other comprehensive gain (loss) - unrealized gain (loss) on swap derivative during the period		0	0	1,617
Forward Contracts | American Assets Trust, L.P.
COMPREHENSIVE INCOME
Other comprehensive gain (loss) - unrealized gain (loss) on swap derivative during the period		$ 0	$ 0	$ 1,617

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

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