Capital Stock (Details 3) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014	Jul. 26, 2016
Share purchases
Aggregate price at which shares of common stock purchased (in dollars)	$ 7,501	$ 5,319	$ 5,067
Additional number of shares authorized to be repurchased (in shares)	1,171,170
Common Stock
Share purchases
Shares of common stock authorized to be repurchased (in shares)				1,000,000
Shares of common stock purchased (in shares)	310,091	250,763	210,841
Aggregate price at which shares of common stock purchased (in dollars)	$ 7,501	$ 5,319	$ 5,067
Number of shares of common stock held in treasury (in shares)		2,000	1,000
Common Stock | Maximum
Share purchases
Shares of common stock authorized to be repurchased (in shares)			4,500,000
Common Stock | Direct Stock Purchase Plan
Share purchases
Shares registered (in shares)	1,500,000
Shares purchased (in shares)	3,343	4,291
Shares of common stock available for purchase (in shares)	1,374,101