Net Income Per Share Data - Additional Information (Detail) - USD ($)			3 Months Ended		9 Months Ended
	Jul. 08, 2015	Nov. 11, 2014	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Nov. 05, 2014
Earnings Loss Per Share [Line Items]
Weighted average diluted shares outstanding excluded outstanding stock options			200,000	600,000	300,000	400,000
Common stock repurchased, Shares		758,143				485,577
Common stock repurchased						$ 11,500,000
Accelerated Share Repurchase Program [Member]
Earnings Loss Per Share [Line Items]
Maximum payments for repurchase of common stock							$ 30,000,000
Common stock repurchased, Shares		847,864
Amount available for repurchases of shares							$ 10,000,000
Fair value of common stock		$ 16,000,000
Shares repurchased		758,143
Initial payment to bank reported as reduction in retained earnings		$ 4,000,000
Accelerate share repurchase program, price per share		$ 23.59
Accelerated Share Repurchase Program [Member] | Maximum [Member]
Earnings Loss Per Share [Line Items]
Reduction in common stock		$ 100,000
Reduction in additional paid-in capital		2,500,000
Reduction in retained earnings		13,500,000
Accelerated Share Repurchase Program [Member] | Investment Bank [Member]
Earnings Loss Per Share [Line Items]
Fair value of common stock		$ 20,000,000
Subsequent Event [Member] | Accelerated Share Repurchase Program [Member]
Earnings Loss Per Share [Line Items]
Common stock repurchased, Shares	89,721