Business Acquisitions - Proforma information (Details) - Titan - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2018	Oct. 31, 2017
Pro forma information
Pro forma net sales	$ 833,837	$ 777,146	$ 1,657,137	$ 1,544,980
Pro forma operating income	$ 24,912	$ 20,438	$ 30,079	$ 37,674

Amount after tax of pro forma income from continuing operations as if the business combination had been completed at the beginning of a period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(2)-(3)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

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Balance Type:	credit
Period Type:	duration