RETIREMENT PLANS - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
Jun. 30, 2021	Jun. 30, 2020
Retirement Benefits [Abstract]
Employee Stock Ownership Plan (ESOP), Shares contributed to ESOP, value	$ 2.3	$ 3.6

Employee Stock Ownership Plan (ESOP), Shares Contributed to ESOP, Value

No definition available.

Name:	cswi_EmployeeStockOwnershipPlanESOPSharesContributedToESOPValue
Namespace Prefix:	cswi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration