Summary of Carrying Amount and Estimated Fair Value of Held-to-Maturity Debt Securities and Amortized Cost and Estimated Fair Value of Available-for-Sale Debt Securities by Contractual Maturity (Parenthetical) (Detail) (Other Debt Securities, USD $)	Sep. 30, 2013
Investments Classified by Contractual Maturity Date [Line Items]
Due after ten years	$ 32,275,000	[1],[2]
Due after ten years	101,535,000	[2]
Pooled trust preferred securities
Investments Classified by Contractual Maturity Date [Line Items]
Due after ten years	15,500,000
Due after ten years	$ 407,000

[1] As equity securities have no contractual maturity, they have been excluded from this table.

[2] Includes corporate bonds and capital trust notes. Included in capital trust notes are $15.5 million and $407,000 of pooled trust preferred securities available for sale and held to maturity, respectively, all of which are due after ten years. The remaining capital trust notes consist of single-issue trust preferred securities.