Business Acquisitions - Pro forma information (Details) - Titan - USD ($) $ in Thousands	12 Months Ended
Apr. 30, 2019	Apr. 30, 2018
Pro forma information
Pro forma net sales	$ 3,161,188	$ 2,989,873
Pro forma net income	$ 52,519	$ 68,956

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/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(2)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

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

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Period Type:	duration