Securities - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Held to maturity securities, Carrying Value		$ 110,699,000	$ 0
Income tax expense related to net realized gains and losses		50,000	155,000	$ 0
Available for sale securities transferred to held to maturity, total amortized cost	$ 105,300,000
Available for sale securities transferred to held to maturity fair value	103,800,000
Net unrealized loss, net of taxes, on securities at date of transfer	$ (999,000)
Other than temporary impairment (OTTI) charge on equity investments		0	0	$ 0
Ohio Linked Deposit Program [Member]
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Securities pledged for investment in Ohio Linked Deposit Program		$ 0	$ 501,000