Selected Quarterly Data (Unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	May 31, 2012	Feb. 29, 2012	Nov. 30, 2011	Aug. 31, 2011	May 31, 2011	Feb. 28, 2011	Nov. 30, 2010	Aug. 31, 2010	May 31, 2012	May 31, 2011	May 31, 2010
Selected Quarterly Data (Unaudited)
Sales	$ 563,346	$ 534,195	$ 481,922	$ 485,535	$ 487,826	$ 458,035	$ 447,054	$ 412,197	$ 2,064,998	$ 1,805,112	$ 1,352,151
Gross profit	77,335	86,958	78,556	75,708	83,199	78,793	74,176	70,888	318,557	307,056	243,519
Net income attributable to AAR	$ 12,879	$ 20,663	$ 17,532	$ 16,649	$ 21,420	$ 17,918	$ 16,814	$ 13,674	$ 67,723	$ 69,826	$ 44,628
Diluted earnings per share-continuing operations (in dollars per share)	$ 0.32	$ 0.50	$ 0.43	$ 0.41	$ 0.52	$ 0.44	$ 0.42	$ 0.35	$ 1.65	$ 1.73
Dividends declared (in dollars per share)	$ 0.075	$ 0.075	$ 0.075	$ 0.075	$ 0.075				$ 0.30	$ 0.075
Low Market Price (in dollars per share)	$ 12.05	$ 16.72	$ 15.17	$ 21.89	$ 25.02	$ 25.19	$ 16.48	$ 15.23	$ 12.05	$ 15.23
High Market Price (in dollars per share)	$ 22.68	$ 23.37	$ 23.04	$ 31.42	$ 28.06	$ 29.03	$ 24.56	$ 19.15	$ 31.42	$ 29.03