Derivatives - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
TBA Securities
Derivative [Line Items]
Notional amount	$ 12,000,000
Closed hedge not settled	3,000,000
Not Designated as Hedging Instrument | Interest Rate Lock Commitments - Best Efforts
Derivative [Line Items]
Notional amount	17,700,000
Not Designated as Hedging Instrument | Interest Rate Lock Commitments - Loans Held-for-sale - Best Efforts
Derivative [Line Items]
Notional amount	3,000,000
Not Designated as Hedging Instrument | Interest Rate Lock Commitments - Borrowers - Best Efforts
Derivative [Line Items]
Notional amount	$ 14,700,000
Not Designated as Hedging Instrument | Interest Rate Lock Commitments - Mandatory Delivery
Derivative [Line Items]
Notional amount		$ 14,900,000
Not Designated as Hedging Instrument | Interest Rate Lock Commitments - Borrowers - Mandatory Delivery
Derivative [Line Items]
Notional amount		12,100,000
Not Designated as Hedging Instrument | Interest Rate Lock Commitments - Loans Held-for-sale - Mandatory Delivery
Derivative [Line Items]
Notional amount		2,800,000
Not Designated as Hedging Instrument | Mortgage loan commitments best efforts
Derivative [Line Items]
Notional amount		25,300,000
Not Designated as Hedging Instrument | Mortgage Loan Commitments - Borrowers - Best Efforts
Derivative [Line Items]
Notional amount		16,400,000
Not Designated as Hedging Instrument | Mortgage Loan Commitments - Loans Held-for-sale - Best Efforts
Derivative [Line Items]
Notional amount		8,900,000
Not Designated as Hedging Instrument | Mortgage loan commitments mandatory delivery
Derivative [Line Items]
Notional amount		$ 0
Minimum | TBA Securities
Derivative [Line Items]
Settlement term	30 days
Maximum | TBA Securities
Derivative [Line Items]
Settlement term	90 days