Fair Value Measurements (Detail) - USD ($) $ in Thousands	9 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Change due to accretion	$ (376)	$ (1,950)
Deacon
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Balance at beginning of period	392
Change due to accretion	0
Change in estimate	(392)
Balance at end of period	0
SureSeal
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Balance at beginning of period	5,462
Change due to accretion	685
Change in estimate	0
Balance at end of period	$ 6,147

Business combination contingent consideration arrangements change in amount of contingent consideration liability before offset by change in estimate.

No definition available.

+ Details

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

- Definition

Amount of increase (decrease) in the value of a contingent consideration liability, including, but not limited to, differences arising upon settlement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 4
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e7008-128479

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Fair value of financial obligations, including, but not limited to, debt instruments, derivative liabilities, federal funds purchased and sold under agreements to repurchase, securities loaned or sold under agreements to repurchase, financial instruments sold not yet purchased, guarantees, line of credit, loans and notes payable, servicing liability, and trading liabilities.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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- Details

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