Business Segment Information (Details) $ in Millions	3 Months Ended	9 Months Ended
Feb. 28, 2019 USD ($)	Feb. 28, 2018 USD ($)	Feb. 28, 2019 USD ($) segment	Feb. 28, 2018 USD ($)
Business Segment Information
Number of business segments \| segment			2
Sales	$ 529.5	$ 456.3	$ 1,489.1	$ 1,274.8
Gross profit	85.3	77.6	234.8	209.9
Aviation Services
Business Segment Information
Sales	497.3	429.0	1,398.6	1,192.0
Gross profit	81.7	72.1	223.7	195.9
Expeditionary Services
Business Segment Information
Sales	32.2	27.3	90.5	82.8
Gross profit	$ 3.6	$ 5.5	$ 11.1	$ 14.0

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

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-Name Accounting Standards Codification
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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-SubTopic 10
-Section 50
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