Reconciliation of Basic and Diluted Earnings Per Share Attributable to Common Stock (Parenthetical) (Detail) (USD $)	3 Months Ended			9 Months Ended
	Jun. 30, 2013	Jun. 30, 2012		Jun. 30, 2013	Jun. 30, 2012
Income Per Common Share [Line Items]
Basic earnings per share	$ 0.50	$ 0.14	[1]	$ 1.65	$ 1.26	[1]
Diluted earnings per share	$ 0.50	$ 0.14	[1]	$ 1.64	$ 1.25	[1]
Weighted average shares outstanding basic	7,873,698	7,846,417	[1]	7,861,425	7,839,983	[1]
Weighted average shares outstanding diluted	7,922,556	7,872,423	[1]	7,900,126	7,881,187	[1]
Scenario, Adjustment
Income Per Common Share [Line Items]
Basic earnings per share		$ 0.15			$ 1.27
Diluted earnings per share		$ 0.14			$ 1.26
Weighted average shares outstanding basic		7,846,417			7,839,983
Weighted average shares outstanding diluted		7,924,009			7,934,367

[1] Prior year earnings per share calculations have been adjusted for the two-class method to reflect restricted shares that were not reflected as participating in prior periods. Basic earnings per share as previously reported for the quarter and nine months ended June 30, 2012 was $0.15 and $1.27, respectively. Diluted earnings per share as previously reported for the quarter and nine months ended June 30, 2012 was $0.14 and $1.26, respectively. Basic weighted average shares outstanding as previously reported for the quarter and nine months ended June 30, 2012 were 7,846,417 and 7,839,983, respectively. Diluted weighted average shares outstanding as previously reported for the quarter and nine months ended June 30, 2012 were 7,924,009 and 7,934,367, respectively. The impact on all prior period financial statements is deemed immaterial.