Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2009
Consolidated Statements of Operations [Abstract]
Revenues	$ 562,397	$ 550,692	$ 665,851
Cost of goods sold	462,467	408,635	520,802
Gross profit	99,930	142,057	145,049
Selling, general and administrative expenses	85,058	84,457	79,954
Amortization of intangible assets	4,752	4,477	3,460
Impairments	7,158	7,452
Operating income	2,962	45,671	61,635
Gain on sale of investment	(1,229)
Interest expense	408	870	1,107
Interest income	(214)	(260)	(131)
Income before income taxes	3,997	45,061	60,659
Income tax provision	6,712	19,894	20,734
Net income (loss)	(2,715)	25,167	39,925
Net (income) loss attributable to noncontrolling interest		(159)	(208)
Net income (loss) attributable to Powell Industries, Inc.	$ (2,715)	$ 25,008	$ 39,717
Earnings (loss) per share attributable to Powell Industries, Inc.:
Basic	$ (0.23)	$ 2.17	$ 3.48
Diluted	$ (0.23)	$ 2.14	$ 3.43
Weighted average shares:
Basic	11,735	11,545	11,424
Diluted	11,735	11,693	11,591