Derivatives and Hedging Activities - Effect of derivatives in fair value hedging relationships (Details) - Fair value hedging - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effect of fair value hedging derivative financial instruments on the consolidated statement of operations
Amount of Gain (Loss) Recognized in Income on Derivative	$ 136	$ (585)	$ 2,206
Amount of Gain (Loss) Recognized in Income on Hedged Item	(592)	106	82
Interest expense | Brokered CD's
Effect of fair value hedging derivative financial instruments on the consolidated statement of operations
Amount of Gain (Loss) Recognized in Income on Derivative	(220)	(657)	1,972
Amount of Gain (Loss) Recognized in Income on Hedged Item	(145)	371	458
Noninterest income | Corporate Bonds
Effect of fair value hedging derivative financial instruments on the consolidated statement of operations
Amount of Gain (Loss) Recognized in Income on Derivative	356	0	0
Amount of Gain (Loss) Recognized in Income on Hedged Item	(447)	0	0
Interest revenue | Corporate Bonds
Effect of fair value hedging derivative financial instruments on the consolidated statement of operations
Amount of Gain (Loss) Recognized in Income on Derivative	0	72	234
Amount of Gain (Loss) Recognized in Income on Hedged Item	$ 0	$ (265)	$ (376)