Loans and Allowance for Loan Losses - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Financing Receivable Recorded Investment Past Due [Line Items]
Carrying value of PCI loans	$ 78,313,000		$ 78,313,000		$ 88,835,000
Accretion of interest income			3,615,000	$ 848,000
Non-accrual loans	3,000,000		3,000,000		3,205,000
Recorded investment in troubled debt restructurings	8,603,000		8,603,000		8,604,000
Allocation to specific reserves	90,000		90,000		172,000
Commitments to lend additional amounts to customers	4,000		4,000		2,000
Payment default for loans modified as troubled debt restructurings		$ 0	0	0
Purchased Credit Impaired
Financing Receivable Recorded Investment Past Due [Line Items]
Carrying value of PCI loans	78,313,000		78,313,000		88,835,000
Purchase accounting liquidity discount			4,212,000
Purchase accounting nonaccretable credit discount			5,236,000
Accretion of interest income	2,639,000	589,000	4,840,000	1,612,000
Total purchase accounting contribution through accretion for purchased loans	1,928,000	$ 848,000	3,615,000	$ 2,008,000
Non-accrual loans	0		0		0
Non-Purchased Credit Impaired
Financing Receivable Recorded Investment Past Due [Line Items]
Purchase accounting liquidity discount			3,018,000
Purchase accounting accretable credit discount			9,337,000
Federal Reserve | Borrower in Custody Program
Financing Receivable Recorded Investment Past Due [Line Items]
Gross loans	1,218,505,000		1,218,505,000		724,312,000
Federal Home Loan Bank of Cincinnati | Qualifying Residential Mortgage Loans
Financing Receivable Recorded Investment Past Due [Line Items]
Gross loans	598,522,000		598,522,000		761,197,000
Federal Home Loan Bank of Cincinnati | Qualifying Commercial Mortgage Loans
Financing Receivable Recorded Investment Past Due [Line Items]
Gross loans	$ 539,621,000		$ 539,621,000		$ 207,370,000