Inventories - Schedule of Impact on the Company's Condensed Consolidated Balance Sheets (Detail) - USD ($) $ in Thousands	Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2017
Inventory [Line Items]
Inventories	$ 17,206	$ 18,549
Total Current Assets	65,357	64,391
Deferred Income Taxes	1,829	1,869
Prepaid expenses and other current assets	3,736	2,224
Total Assets	87,223	85,083
Retained earnings	43,552	43,836
Total Kewaunee Scientific Corporation Stockholders’ Equity	47,100	47,730	$ 43,461
Total Stockholders’ Equity	47,703	48,192
Total Liabilities and Stockholders’ Equity	87,223	$ 85,083
Adjustments
Inventory [Line Items]
Inventories	(1,331)
Total Current Assets	(1,331)
Deferred Income Taxes	156
Prepaid expenses and other current assets	164
Total Assets	(1,011)
Retained earnings	(1,011)
Total Kewaunee Scientific Corporation Stockholders’ Equity	(1,011)
Total Stockholders’ Equity	(1,011)
Total Liabilities and Stockholders’ Equity	(1,011)
LIFO
Inventory [Line Items]
Inventories	15,875
Total Current Assets	64,026
Deferred Income Taxes	1,985
Prepaid expenses and other current assets	3,900
Total Assets	86,212
Retained earnings	42,541
Total Kewaunee Scientific Corporation Stockholders’ Equity	46,089
Total Stockholders’ Equity	46,692
Total Liabilities and Stockholders’ Equity	$ 86,212