Goodwill and Other Intangible Assets - Estimated Core Deposit Intangible Amortization Excluding Impact of any Future Acquisitions (Detail) (Core deposit intangibles [Member], USD $) In Thousands, unless otherwise specified	Sep. 30, 2014
Core deposit intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
2014	$ 209
2015	209
2016	209
2017	209
2018	47
Thereafter