Derivative Instruments and Hedging Activities - Interest Rate Derivatives Designated as Hedges (Details) - Fair value hedge - Derivatives designated as hedging instruments - Interest rate swaps $ in Thousands	Sep. 30, 2018 USD ($)
Derivative [Line Items]
Carrying Amount of the Hedged Asset	$ 7,942
Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Asset	$ 345