Business Segment Information (Details) $ in Millions	3 Months Ended
Aug. 31, 2018 USD ($) segment	Aug. 31, 2017 USD ($)
Business Segment Information
Number of business segments \| segment	2
Net sales	$ 466.3	$ 397.9
Gross profit	71.2	61.6
Aviation Services
Business Segment Information
Net sales	438.4	371.3
Gross profit	67.1	57.8
Expeditionary Services
Business Segment Information
Net sales	27.9	26.6
Gross profit	$ 4.1	$ 3.8

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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