Business Combination - Summary of Estimated Fair Values of Assets Acquired and Liabilities Assumed at Date of Acquisition (Parenthetical) (Detail) - Colonial American Bank [Member]	Jul. 31, 2015 USD ($)
Business Acquisition [Line Items]
Fair value deduction on loans	$ 1,700,000
Fair value deduction on credit-impaired loans	1,200,000
Interest rate fair value benefit on loans	980,000
Write-off of capitalized loan origination costs	$ 1,700,000