Derivatives and Hedging Activities - Narrative (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($) customer swap	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) customer swap	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($) customer swap
Derivative [Line Items]
Accrued interest on derivatives, at fair value	$ 63,000		$ 63,000		$ 65,000
Derivative, net liability position, aggregate fair value	12,300,000		12,300,000
Derivative, collateral, right to reclaim cash	16,300,000		16,300,000
Interest Rate Swap
Derivative [Line Items]
Derivative gain (loss) on derivative, net	146,000	$ 0	213,000	$ 0
Not-designated hedge | Currency forward contract - non-designated hedge
Derivative [Line Items]
Notional amount of derivative	0		0		0
Not-designated hedge | Interest Rate Swap
Derivative [Line Items]
Notional amount of derivative	$ 76,300,000		$ 76,300,000		$ 36,600,000
Number of swaps with customers offset by third party swaps | customer	9		9		3
Federal Home Loan Bank Advances | Designated as Hedging Instrument | Interest Rate Swap
Derivative [Line Items]
Notional amount of derivative	$ 400,000,000		$ 400,000,000		$ 320,000,000
Number of interest rate derivatives held | swap	28		28		24