Derivatives and Hedging Activities (Narrative) (Details)	3 Months Ended
	Mar. 31, 2020 USD ($) counterparty instrument	Dec. 31, 2019 USD ($) instrument
Derivative [Line Items]
Derivative instruments in accumulated other comprehensive income reclassified to interest expense	$ 2,100,000
Derivative liability, notional amount	$ 290,000,000.0
Number of counterparties | counterparty	4
Counterparty in liability position | counterparty	4
Derivative liabilities	$ 127,700,000
Collateral against obligations	128,700,000
Derivatives Not Designated as a Hedging Instruments
Derivative [Line Items]
Credit derivatives, fair value	$ 90,000	$ 47,000
Derivatives Not Designated as a Hedging Instruments | Interest rate products
Derivative [Line Items]
Number of derivative instruments held (in instrument) | instrument	116	92
Derivative notional amount	$ 1,970,000,000	$ 1,610,000,000
Derivatives Not Designated as a Hedging Instruments | Credit contracts
Derivative [Line Items]
Number of derivative instruments held (in instrument) | instrument	13
Derivative notional amount	$ 106,800,000	$ 106,000,000.0
Designated as Hedging Instrument
Derivative [Line Items]
Number of outstanding derivatives | instrument	9