Stock-Based Compensation Plans (Tables) - Summary of Stock Activity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	6 Months Ended
	Mar. 31, 2013 Years	Sep. 30, 2012
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Options outstanding at October 1, 2012	481,210
Options granted	46,180
Options exercised	93,300
Options outstanding at March 31, 2013	434,090
Options outstanding weighted average exercise price-beginning balance	$ 17.52
Options outstanding weighted average exercise price - Granted	$ 26.20
Options outstanding weighted average exercise price - Exercised	$ 10.67
Options outstanding weighted average exercise price - Ending balance	$ 19.92
Options outstanding weighted average remaining term	4.5	3.8
Options outstanding weighted average grant date fair value - beginning balance	$ 3,782
Options granted weighted average grant date fair value	489
Options exercised weighted average grant date fair value	505
Options outstanding weighted average grant date fair value - ending balance	3,766
Options exercisable at March 31, 2013	338,078
Options exerciseable weighted average exercise price	$ 18.31
Options exerciseable weighted average remaining term	3.4
Options exerciseable weighted average grant date fair value	2,730
Options vested during six months ended March 31, 2013	20,612
Options vested weighted average grant date fair value	$ 199