Derivative Instruments - Amounts and Locations of Activity Related to Interest Rate Swaps Designated as Cash Flow Hedges within Corporation's Consolidated Balance Sheet and Statement of Income (Details) - Interest Rate Swaps - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Derivative [Line Items]
Interest rate contracts	$ (45)	$ 36	$ (302)	$ 134
Accrued interest and other liabilities
Derivative [Line Items]
Accrued interest and other liabilities	(583)		(583)		$ (201)
Interest expense – subordinated debentures
Derivative [Line Items]
Other income	(11)	(44)	(31)	(149)
Other income
Derivative [Line Items]
Other income	$ 0	$ 0	$ 0	$ 0