Derivatives and Hedging Activities (Narrative) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) instrument counterparty	Dec. 31, 2018 USD ($) instrument
Derivative [Line Items]
Derivative instruments in accumulated other comprehensive income reclassified to interest expense	$ 520
Derivative liability, notional amount	$ 60,000
Number of counterparties | counterparty	4
Counterparty in liability position | counterparty	3
Derivative liabilities	$ 11,800
Collateral against obligations	13,400
Derivatives Not Designated as a Hedging Instruments [Member]
Derivative [Line Items]
Credit derivatives, fair value	$ 301	$ 251
Derivatives Not Designated as a Hedging Instruments [Member] | Interest rate products [Member]
Derivative [Line Items]
Number of derivative instruments held (in instrument) | instrument	66	62
Derivative notional amount	$ 1,020,000	$ 1,010,000
Derivatives Not Designated as a Hedging Instruments [Member] | Credit contracts [Member]
Derivative [Line Items]
Number of derivative instruments held (in instrument) | instrument	12	7
Derivative notional amount	$ 87,600	$ 66,800
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Number of outstanding derivatives | instrument	2