Segment Information - Segment Information (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Apr. 30, 2017	Jan. 31, 2017	Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2016	Jan. 31, 2016	Oct. 31, 2015	Jul. 31, 2015	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2015
Segment Reporting Information [Line Items]
Revenues									$ 138,558	$ 128,626	$ 118,828
Depreciation									2,702	2,592	2,615
Earnings (loss) before income taxes									6,746	5,739	5,385
Income tax expense (benefit)									2,126	1,862	1,745
Net earnings attributable to noncontrolling interest	$ 7	$ 17	$ 51	$ 30	$ 22	$ 18	$ 12	$ 23	105	75	111
Net earnings (loss) attributable to Kewaunee Scientific Corporation	1,388	$ 341	$ 1,486	$ 1,300	1,337	$ 830	$ 695	$ 940	4,515	3,802	3,529
Segment assets	80,916				72,405				80,916	72,405	69,490
Expenditures for segment assets									2,611	2,187	2,568
Non-US [Member]
Segment Reporting Information [Line Items]
Revenues									27,045	27,373	26,899
Corporate [Member]
Segment Reporting Information [Line Items]
Intersegment revenues									(8,154)	(6,921)	(3,852)
Earnings (loss) before income taxes									(4,982)	(4,470)	(3,498)
Income tax expense (benefit)									(1,595)	(1,076)	(1,141)
Net earnings (loss) attributable to Kewaunee Scientific Corporation									(3,387)	(3,394)	(2,357)
Domestic [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues									113,081	103,047	93,098
Intersegment revenues									4,463	3,612	1,433
Depreciation									2,478	2,375	2,399
Earnings (loss) before income taxes									8,221	7,471	5,810
Income tax expense (benefit)									2,522	1,834	1,794
Net earnings (loss) attributable to Kewaunee Scientific Corporation									5,699	5,637	4,016
Segment assets	57,246				54,030				57,246	54,030	52,723
Expenditures for segment assets									2,572	1,995	2,259
Domestic [Member] | Operating Segments [Member] | Non-US [Member]
Segment Reporting Information [Line Items]
Revenues									1,568	1,794	1,169
International [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues									25,477	25,579	25,730
Intersegment revenues									3,691	3,309	2,419
Depreciation									224	217	216
Earnings (loss) before income taxes									3,507	2,738	3,073
Income tax expense (benefit)									1,199	1,104	1,092
Net earnings attributable to noncontrolling interest									105	75	111
Net earnings (loss) attributable to Kewaunee Scientific Corporation									2,203	1,559	1,870
Segment assets	$ 23,670				$ 18,375				23,670	18,375	16,767
Expenditures for segment assets									39	192	309
International [Member] | Operating Segments [Member] | Non-US [Member]
Segment Reporting Information [Line Items]
Revenues									$ 25,477	$ 25,579	$ 25,730