Segment Reporting Reconciliation of Segment Profit to Net Income Attributable to Stockholders (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting [Abstract]
Total segments' profit									$ 187,157	$ 177,617	$ 168,769
General and administrative									(17,897)	(20,074)	(18,532)
Depreciation and amortization									(71,319)	(63,392)	(66,568)
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	$ 12,408	$ 11,858	$ 10,650	$ 10,721	$ 11,226	$ 19,026	$ 12,284	$ 11,379	45,637	53,915	31,145
Net income attributable to restricted shares	(61)	(42)	(43)	(43)	(53)	(32)	(40)	(43)	(189)	(168)	(374)
Net income attributable to unitholders in the Operating Partnership	(3,486)	(3,342)	(3,008)	(3,027)	(2,961)	(5,432)	(3,536)	(3,309)	(12,863)	(15,238)	(9,015)
Net income attributable to American Assets Trust, L.P. unit holders	$ 8,861	$ 8,474	$ 7,599	$ 7,651	$ 8,212	$ 13,562	$ 8,708	$ 8,027	$ 32,585	$ 38,509	$ 21,756