Summary of Significant Accounting Policies (Details 7) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	May 31, 2012	May 31, 2011	May 31, 2010
Comprehensive Income
Net income attributable to AAR and noncontrolling interest	$ 68,029	$ 69,826	$ 43,202
Other comprehensive income
Cumulative translation adjustments, net of tax	(18,474)	3,290	(2,238)
Unrealized loss on derivatives instruments, net of tax	(3,887)
Unrecognized pension and post retirement costs, net of tax	(14,184)	7,711	(3,412)
Total comprehensive income	31,484	80,827	37,552
Supplemental Information on Cash Flows
Interest paid	16,566	17,167	13,629
Income taxes paid	11,418	9,812	30,149
Income tax refunds and interest received	$ 7,205	$ 4,541	$ 709
Building and improvements
Property, Plant and Equipment
Minimum useful life (in years)	10
Maximum useful life (in years)	40
Equipment
Property, Plant and Equipment
Minimum useful life (in years)	3
Maximum useful life (in years)	10
Furniture and fixtures
Property, Plant and Equipment
Minimum useful life (in years)	3
Maximum useful life (in years)	10
Capitalized software
Property, Plant and Equipment
Minimum useful life (in years)	3
Maximum useful life (in years)	10
Aircraft and components
Property, Plant and Equipment
Minimum useful life (in years)	7
Maximum useful life (in years)	20