Derivative Instruments and Hedging Activities - Interest Rate Derivatives Designated as Hedges (Details) - Fair value hedge - Derivatives designated as hedging instruments - Interest rate swaps - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Carrying Amount of the Hedged Asset	$ 7,811	$ 7,882
Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Asset	$ 337	$ 346