Loans and Allowance for Loan Losses - Schedule of Impaired Loans and Related Allowance (Parenthetical) (Detail) - USD ($)	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Receivables [Abstract]
Carrying amount of purchased credit impaired loans	$ 1,970,000	$ 2,178,000	$ 2,037,000