v2.4.0.6
Document and Entity Information (USD $)
12 Months Ended
Mar. 31, 2012
May 01, 2012
Sep. 30, 2011
Document and Entity Information [Abstract]      
Entity Registrant Name CAPITAL SOUTHWEST CORP    
Entity Central Index Key 0000017313    
Current Fiscal Year End Date --03-31    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Filer Category Accelerated Filer    
Entity Public Float     $ 193,363,554
Entity Common Stock, Shares Outstanding   3,754,538  
Document Fiscal Year Focus 2012    
Document Fiscal Period Focus FY    
Document Type 10-K    
Amendment Flag false    
Document Period End Date Mar. 31, 2012