Business Segment Information - Sales and Gross Profit (Details) - USD ($) $ in Millions	12 Months Ended
May 31, 2022	May 31, 2021	May 31, 2020
Disaggregation of revenue by major customer markets
Sales	$ 1,820.0	$ 1,652.3	$ 2,072.0
Gross profit	313.2	275.9	269.2
Aviation Services
Disaggregation of revenue by major customer markets
Sales	1,745.8	1,553.7	1,964.2
Gross profit	297.5	263.2	267.3
Aviation Services \| Commercial
Disaggregation of revenue by major customer markets
Sales	1,081.6	793.9	1,268.9
Aviation Services \| Government and defense
Disaggregation of revenue by major customer markets
Sales	664.2	759.8	695.3
Expeditionary Services
Disaggregation of revenue by major customer markets
Sales	74.2	98.6	107.8
Gross profit	15.7	12.7	1.9
Expeditionary Services \| Commercial
Disaggregation of revenue by major customer markets
Sales	2.2	12.5	24.3
Expeditionary Services \| Government and defense
Disaggregation of revenue by major customer markets
Sales	$ 72.0	$ 86.1	$ 83.5

Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

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- Definition

Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.

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