Loans and Leases - Certain Information Relating to Regency Consumer Finance Loans (Detail) - Consumer Lines of Credit [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Loans and Leases Receivable Disclosure [Line Items]
Regency consumer finance loans	$ 184,687	$ 186,162
Loan Portfolio Diversification Risk [Member] | Loans and Leases Receivable Net of Deferred Income [Member]
Loans and Leases Receivable Disclosure [Line Items]
Percent of total loans and leases	1.20%	1.50%