Derivatives and Hedging Activities (Offset Fair Value and Notional Amount) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Asset Derivatives
Total gross derivative amounts recognized on the balance sheet	$ 76,919	$ 109,114
Gross amounts offset on the balance sheet	0	0
Net derivative amounts presented on the balance sheet	76,919	109,114
Financial instruments - institutional counterparties	16,195	928
Cash collateral - institutional counterparties	0	0
Net derivatives not offset	60,724	108,186
Liability Derivatives
Notional Amount	600,000
Total gross derivative amounts recognized on the balance sheet	78,212	117,597
Gross amounts offset on the balance sheet	0	0
Net derivative amounts presented on the balance sheet	78,212	117,597
Financial instruments - institutional counterparties	16,195	928
Cash Collateral	46,895	113,620
Net derivatives not offset	15,122	3,049
Derivatives Not Designated as a Hedging Instruments
Asset Derivatives
Fair Value	72,618	108,616
Total gross derivative amounts recognized on the balance sheet	71,886	107,749
Liability Derivatives
Fair Value	73,719	110,015
Total gross derivative amounts recognized on the balance sheet	72,987	109,148
Derivatives Not Designated as a Hedging Instruments | Credit contracts
Liability Derivatives
Cash Collateral	650
Derivatives Not Designated as a Hedging Instruments | Other assets | Interest rate products
Asset Derivatives
Notional Amount	1,272,593	1,316,163
Fair Value	72,511	108,519
Total gross derivative amounts recognized on the balance sheet	71,779	107,652
Derivatives Not Designated as a Hedging Instruments | Other assets | Credit contracts
Asset Derivatives
Notional Amount	47,712	47,745
Fair Value	107	97
Total gross derivative amounts recognized on the balance sheet	107	97
Derivatives Not Designated as a Hedging Instruments | Other liabilities | Interest rate products
Liability Derivatives
Notional Amount	1,272,593	1,316,163
Fair Value	73,679	109,957
Total gross derivative amounts recognized on the balance sheet	72,947	109,148
Derivatives Not Designated as a Hedging Instruments | Other liabilities | Credit contracts
Liability Derivatives
Notional Amount	92,950	73,954
Fair Value	40	58
Total gross derivative amounts recognized on the balance sheet	40	0
Designated as Hedging Instrument
Asset Derivatives
Total gross derivative amounts recognized on the balance sheet	4,337	(6,671)
Liability Derivatives
Total gross derivative amounts recognized on the balance sheet	4,052	0
Designated as Hedging Instrument | Other assets | Interest rate products
Asset Derivatives
Notional Amount	250,000	175,000
Fair Value	4,301	498
Total gross derivative amounts recognized on the balance sheet	4,337	(6,671)
Designated as Hedging Instrument | Other liabilities | Interest rate products
Liability Derivatives
Notional Amount	350,000	425,000
Fair Value	4,493	7,582
Total gross derivative amounts recognized on the balance sheet	$ 4,052	$ 0