Long-term Debt - Additional Information (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($) InterestRateSwap	Dec. 31, 2016 USD ($)	Dec. 31, 2003 USD ($) trust	Dec. 31, 2015 USD ($) Note
Debt Instrument [Line Items]
Number of subordinated notes payable | Note					3
Fixed rate borrowings		$ 112,372	$ 13,962
Federal home loan bank, Advances, Branch of FHLB bank, Weighted average interest rate		1.45%	3.02%
Federal home loan bank advances maturity and reprice period		90 days
Number of corresponding interest rate swap agreements | InterestRateSwap		3
Number of separate trusts | trust				2
Net proceeds from sale of common stock		$ 153,356	$ 116,054
Debt instrument, redemption, description		The Company may redeem the first junior subordinated debenture listed, in whole or in part, on any distribution payment date within 120 days of the occurrence of a special event, at the redemption price. The Company may redeem the second junior subordinated debentures listed, in whole or in part, any time after June 26, 2008, on any distribution payment date, at the redemption price. The junior subordinated debentures must be redeemed no later than 2033.
Floating Rate Trust Preferred Securities Trust I
Debt Instrument [Line Items]
Preferred securities issued to form the trust				$ 9,000
Debt instrument, basis spread on variable rate				3.25%
Debt instrument, description of variable rate basis		3-month LIBOR plus 3.25%
Debt instrument, interest rate		4.59%	4.25%
Floating Rate Trust Preferred Securities Trust II
Debt Instrument [Line Items]
Preferred securities issued to form the trust				$ 21,000
Debt instrument, basis spread on variable rate				3.15%
Debt instrument, description of variable rate basis		3-month LIBOR plus 3.15%
Debt instrument, interest rate		4.82%	4.15%
Clayton Banks
Debt Instrument [Line Items]
Fixed rate borrowings	$ 100,000
Minimum
Debt Instrument [Line Items]
Federal home loan bank advances maturities due term		1 year
Maximum
Debt Instrument [Line Items]
Federal home loan bank advances maturities due term		12 years
Federal Home Loan Bank of Cincinnati
Debt Instrument [Line Items]
Borrowing capacity at Federal Home Loan Bank of Cincinnati		$ 671,461	$ 476,562
Loans from Federal Home Loan Banks		968,567	565,718
Pledged investment securities		$ 0	60,371
First Note
Debt Instrument [Line Items]
Debt instrument, face amount					$ 775
Second Note
Debt Instrument [Line Items]
Debt instrument, face amount					$ 3,300
Third Note
Debt Instrument [Line Items]
Debt instrument, face amount			$ 6,000
Junior Subordinated Debentures | Floating Rate Trust Preferred Securities Trust I
Debt Instrument [Line Items]
Proceeds from Issuance of Debt				$ 9,280
Net proceeds from sale of common stock				280
Junior Subordinated Debentures | Floating Rate Trust Preferred Securities Trust II
Debt Instrument [Line Items]
Proceeds from Issuance of Debt				21,650
Net proceeds from sale of common stock				$ 650