Equity of American Assets Trust, Inc. Summary of Income Tax Status of Dividends Per Share Paid (Details) - $ / shares	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, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Equity [Abstract]
Ordinary income (in USD per share)													$ 1.01	$ 0.72	$ 0.61
Capital gain (in USD per share)													0.00	0.04	0.00
Return of capital (in USD per share)													0.00	0.19	0.28
Total (in USD per share)	$ 0.26	$ 0.25	$ 0.25	$ 0.25	$ 0.25	$ 0.2325	$ 0.2325	$ 0.2325	$ 0.2325	$ 0.22	$ 0.22	$ 0.22	$ 1.01	$ 0.95	$ 0.89
Ordinary income													100.00%	75.90%	68.90%
Capital gain													0.00%	4.40%	0.00%
Return of capital													0.00%	19.70%	31.10%
Total													100.00%	100.00%	100.00%