Loans - Total Loans on Nonaccrual (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule Of Financing Receivables Non Accrual Status [Line Items]
Total loans on nonaccrual	$ 33,298	$ 26,171	$ 53,891
Gaming [Member]
Schedule Of Financing Receivables Non Accrual Status [Line Items]
Total loans on nonaccrual		1,223	16,249
Residential and Land Development [Member]
Schedule Of Financing Receivables Non Accrual Status [Line Items]
Total loans on nonaccrual	8,233	13,572	21,083
Real Estate, Construction [Member]
Schedule Of Financing Receivables Non Accrual Status [Line Items]
Total loans on nonaccrual	3,287	2,588	5,171
Real Estate, Mortgage [Member]
Schedule Of Financing Receivables Non Accrual Status [Line Items]
Total loans on nonaccrual	21,398	8,788	11,174
Commercial and Industrial [Member]
Schedule Of Financing Receivables Non Accrual Status [Line Items]
Total loans on nonaccrual	$ 380		$ 214