Revenue Recognition (Details) - USD ($) $ in Millions	3 Months Ended
Aug. 31, 2018	Aug. 31, 2017
Revenue Recognition
Favorable cumulative catch-up adjustments	$ 0.7
Unfavorable cumulative catch-up adjustments	0.5
Net cumulative catch-up adjustments	$ 0.2	$ 0.0

Amount of increase (decrease) in revenue recognized for cumulative catch-up adjustment from change in estimates and assumptions used in calculating the cost-to-cost method.

No definition available.

Name:	air_ContractWithCustomerNetCumulativeCatchUpAdjustmentToRevenue
Namespace Prefix:	air_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration