Derivatives and Hedging Activities (Narrative) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2021 USD ($) counterparty instrument	Dec. 31, 2020 USD ($) instrument
Derivative [Line Items]
Derivative instruments in accumulated other comprehensive income reclassified to interest expense	$ 3,500
Derivative liability, notional amount	$ 600,000
Number of counterparties | counterparty	4
Counterparty in liability position | counterparty	4
Derivative liabilities	$ 38,500
Collateral against obligations	42,000
Derivatives Not Designated as a Hedging Instruments
Derivative [Line Items]
Credit derivatives, fair value	$ 96	$ 97
Derivatives Not Designated as a Hedging Instruments | Interest rate products
Derivative [Line Items]
Number of derivative instruments held (in instrument) | instrument	174	172
Derivative notional amount	$ 2,620,000	$ 2,630,000
Derivatives Not Designated as a Hedging Instruments | Credit contracts
Derivative [Line Items]
Number of derivative instruments held (in instrument) | instrument	13
Derivative notional amount	$ 131,400	$ 121,700
Amount of collateral	$ 650
Designated as Hedging Instrument
Derivative [Line Items]
Number of outstanding derivatives | instrument	14