Consolidated Statements Of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010
Consolidated Statements of Operations [Abstract]
Revenues	$ 717,194	$ 562,397	$ 550,692
Cost of goods sold	577,256	462,467	408,635
Gross profit	139,938	99,930	142,057
Selling, general and administrative expenses	88,947	85,058	84,457
Amortization of intangible assets	2,599	4,752	4,477
Impairments		7,158	7,452
Operating income	48,392	2,962	45,671
Gain on sale of investment		(1,229)
Interest expense	272	408	870
Interest income	(114)	(214)	(260)
Income before income taxes	48,234	3,997	45,061
Income tax provision	18,577	6,712	19,894
Net income (loss)	29,657	(2,715)	25,167
Net income attributable to noncontrolling interest			(159)
Net income (loss) attributable to Powell Industries, Inc.:	$ 29,657	$ (2,715)	$ 25,008
Earnings (loss) per share attributable to Powell Industries, Inc.:
Basic	$ 2.50	$ (0.23)	$ 2.17
Diluted	$ 2.49	$ (0.23)	$ 2.14
Weighted average shares:
Basic	11,850	11,735	11,545
Diluted	11,925	11,735	11,693