Derivative Financial Instruments - Narrative (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018 USD ($) interest_rate_swap interest_rate_cap instrument	Sep. 30, 2018 USD ($) interest_rate_swap interest_rate_cap instrument	Dec. 31, 2017 USD ($) interest_rate_swap interest_rate_cap
Derivative [Line Items]
Estimated amount to be transferred from accumulated other comprehensive income to earnings		$ 249
Termination value of derivatives in a net liability position	$ 394	394
Derivative collateral posted	3,315	3,315
Not Designated as Hedging Instrument
Derivative [Line Items]
Notional amount of interest rate derivatives	$ 420,388	$ 420,388
Federal Home Loan Bank Advances
Derivative [Line Items]
Number of debt instruments held | instrument	2	2
Cash Flow Hedging | Interest Rate Swap
Derivative [Line Items]
Number of interest rate derivatives held | interest_rate_swap	4	4	5
Notional amount of interest rate derivatives	$ 46,000	$ 46,000	$ 56,000
Notional amount matured	10,000
Cash Flow Hedging | Interest Rate Swap | Trust Preferred Debt
Derivative [Line Items]
Notional amount of interest rate derivatives	26,000	26,000
Cash Flow Hedging | Interest Rate Swap | Federal Home Loan Bank Advances
Derivative [Line Items]
Notional amount of interest rate derivatives	$ 20,000	$ 20,000
Cash Flow Hedging | Interest Rate Cap
Derivative [Line Items]
Number of interest rate derivatives held | interest_rate_cap	1	1	1
Notional amount of interest rate derivatives	$ 13,000	$ 13,000	$ 13,000
Cash Flow Hedging | Interest Rate Cap | Trust Preferred Debt
Derivative [Line Items]
Notional amount of interest rate derivatives	$ 13,000	$ 13,000