Fair Value Measurements and Disclosures - Assets Measured at Fair Value on Non-Recurring Basis of Other Real Estate (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value on a non-recurring basis, other real estate	$ 7,646	$ 9,630	$ 7,008
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value on a non-recurring basis, other real estate	$ 7,646	$ 9,630	$ 7,008	$ 6,153