Loans - Changes in Credit Fair Value Adjustment on Specific Loans Purchased (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Receivables [Abstract]
Beginning Balance, Carrying value		$ 211
Charge-offs, Carrying value
Loans transferred to other real estate owned, Carrying value
Payments, Carrying value		3
Ending Balance, Carrying value		208
Beginning Balance, Fair Value adjustment		211
Charge-offs, Fair Value adjustment
Loans transferred to other real estate owned, Fair Value adjustment
Payments, Fair Value adjustment		3
Ending Balance, Fair Value adjustment		208
Beginning Balance, Net
Charge-offs, Net
Loans transferred to other real estate owned, Net
Payments, Net
Ending Balance, Net