Loans - Evaluation of Quality of Loan Portfolio (Detail) (Credit Concentration Risk [Member], USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Gaming [Member]
Financing Receivable, Recorded Investment [Line Items]
Total outstanding concentrations	$ 31,353	$ 29,570	$ 60,187
Hotel/Motel [Member]
Financing Receivable, Recorded Investment [Line Items]
Total outstanding concentrations	47,144	49,842	52,776
Out of Area [Member]
Financing Receivable, Recorded Investment [Line Items]
Total outstanding concentrations	$ 19,179	$ 24,945	$ 25,413