Loans and Leases - Summary of Troubled Debt Restructurings by Class of Loans and Leases, Payment Default (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015 Contract		Mar. 31, 2014 Contract
Financing Receivable, Modifications [Line Items]
Number of Contracts	43		19
Recorded Investment	$ 303	[1]	$ 171	[1]
Direct Installment [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	37		18
Recorded Investment	105	[1]	171	[1]
Residential Mortgages [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	2
Recorded Investment	102	[1]
Indirect Installment [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	3		1
Recorded Investment	4	[1]
Consumer Lines of Credit [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	1
Recorded Investment	$ 92	[1]

[1] The recorded investment is as of period end.