Transactions with Executive Officers, Directors, and Principal Shareholders - Schedule of Activity Relating to Loans (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Loans and Leases Receivable, Related Parties [Roll Forward]
Balance – January 1	$ 7,273	$ 3,272	$ 3,657
Additions	5	9,280	14
Repayments	(7,269)	(5,279)	(399)
Balance – December 31	$ 9	$ 7,273	$ 3,272