Document and Entity Information (USD $)	9 Months Ended
	Jun. 30, 2011	Jul. 28, 2011	Mar. 31, 2010
Document and Entity Information [Abstract]
Entity Registrant Name	POWELL INDUSTRIES INC
Entity Central Index Key	0000080420
Document Type	10-Q
Document Period End Date	Jun. 30, 2011
Amendment Flag	true
Amendment Description	Reinstatement of Condensed Consolidated Financial Statements
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--09-30
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Public Float			$ 376,593,000
Entity Common Stock, Shares Outstanding		11,744,909