Derivatives and Hedging Activities (Narrative) (Details)	9 Months Ended
	Sep. 30, 2021 USD ($) counterparty instrument	Dec. 31, 2020 USD ($) instrument
Derivative [Line Items]
Amount of collateral	$ 46,895,000	$ 113,620,000
Derivative instruments in accumulated other comprehensive income reclassified to interest expense	3,300,000
Notional amount	$ 600,000,000
Number of counterparties | counterparty	4
Counterparty in liability position | counterparty	4
Derivative liability, termination value	$ 50,000,000
Collateral against obligations	46,900,000
Derivatives Not Designated as a Hedging Instruments
Derivative [Line Items]
Credit derivatives, fair value	$ 106,500	$ 97,000
Derivatives Not Designated as a Hedging Instruments | Interest rate products
Derivative [Line Items]
Number of derivative instruments held | instrument	170	172
Derivative notional amount	$ 2,550,000,000	$ 2,630,000,000
Derivatives Not Designated as a Hedging Instruments | Credit contracts
Derivative [Line Items]
Number of derivative instruments held | instrument	13
Derivative notional amount	$ 140,700,000	$ 121,700,000
Amount of collateral	$ 650,000
Designated as Hedging Instrument
Derivative [Line Items]
Number of outstanding derivatives | instrument	14