Fair Value (Assets Measured at Fair Value on Nonrecurring Basis) (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure, nonrecurring	$ 12,982	$ 12,349
Fair value measured on nonrecurring basis losses	21,157	17,346
Impaired Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure, nonrecurring	11,220	11,011
Fair value measured on nonrecurring basis losses	21,384	17,655
Other Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure, nonrecurring	1,762	1,338
Fair value measured on nonrecurring basis losses	(227)	(309)
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure, nonrecurring	12,982	12,349
Fair Value, Inputs, Level 3 [Member] | Impaired Loans [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure, nonrecurring	11,220	11,011
Fair Value, Inputs, Level 3 [Member] | Other Real Estate Owned [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure, nonrecurring	$ 1,762	$ 1,338