Changes in Product Warranty Reserve (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Changes in product warranty reserve
Balance at the beginning of the year	$ 1,952	$ 2,308	$ 2,123
Accruals for warranties issued during the year	324	681	1,354
Settlements made (in cash or in kind) during the year	(1,325)	(1,037)	(1,169)
Balance at the end of the year	$ 951	$ 1,952	$ 2,308