Loans and Leases - Accruing and Nonaccrual Troubled Debt Restructured Loans with Payment Defaults (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014 Loans	Dec. 31, 2013 Loans
Accrual Troubled Debt Restructuring Loans [Member]
Accruing and nonaccrual troubled debt restructured loans with payment default
Number of Loans	0	1
Recorded Investment	$ 0	$ 1,000
Accrual Troubled Debt Restructuring Loans [Member] | Commercial, Financial and Agricultural [Member]
Accruing and nonaccrual troubled debt restructured loans with payment default
Number of Loans	0	1
Recorded Investment	0	1,000
Nonaccrual Troubled Debt Restructured Loans [Member]
Accruing and nonaccrual troubled debt restructured loans with payment default
Number of Loans	0	0
Recorded Investment	$ 0	$ 0