Net Income Per Share Data - Denominator for Computation of Basic and Diluted Net Income Per Share (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Earnings Per Share [Abstract]
Net income available to common shareholders	$ 3,051	$ 2,459	$ 6,665	$ 6,089
Basic weighted average shares outstanding	12,944	13,538	13,092	13,658
Dilutive effect of outstanding stock options, non-vested restricted stock, restricted stock units, deferred stock units and performance shares	263	286	273	267
Diluted weighted average shares outstanding	13,207	13,824	13,365	13,925