ACQUISITIONS - Unaudited Proforma Financial Information (Details) - Aspen Manufacturing LLC - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Jun. 30, 2025	Jun. 30, 2024
Business Combination [Line Items]
Revenues, net	$ 274,089	$ 261,215
Net income attributable to CSW Industrials, Inc.	$ 40,736	$ 40,070
Net income per share attributable to CSW Industrials, Inc.
Basic (in dollars per share)	$ 2.42	$ 2.58
Diluted (in dollars per share)	$ 2.42	$ 2.57