Allowance for Credit Losses (Changes in Allowance for Credit Losses) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
LOANS AND LEASES
Balance at Beginning of Period	$ 138,200,000	$ 148,800,000	$ 138,400,000	$ 190,700,000
Charge-Offs	(5,400,000)	0	(5,500,000)	(400,000)
Recoveries	900,000	1,100,000	9,700,000	5,600,000
Net Recoveries (Charge-Offs)	(4,500,000)	1,100,000	4,200,000	5,200,000
Provision for Credit Losses	5,000,000.0	(6,000,000.0)	(3,900,000)	(52,000,000.0)
Balance at End of Period	138,700,000	143,900,000	138,700,000	143,900,000
UNDRAWN LOAN COMMITMENTS AND STANDBY LETTERS OF CREDIT
Balance at Beginning of Period	43,500,000	46,500,000	34,100,000	61,100,000
Charge-Offs	0	0	0	0
Recoveries	0	0	0	0
Net Recoveries (Charge-Offs)	0	0	0	0
Provision for Credit Losses	(2,800,000)	(6,700,000)	6,600,000	(21,300,000)
Balance at End of Period	40,700,000	39,800,000	40,700,000	39,800,000
HELD TO MATURITY DEBT SECURITIES
Balance at Beginning of Period	15,400,000	10,500,000	11,200,000	7,300,000
Charge-Offs	0	0	0	0
Recoveries	0	0	0	0
Net Recoveries (Charge-Offs)	0	0	0	0
Provision for Credit Losses	(400,000)	(100,000)	3,800,000	3,100,000
Balance at End of Period	15,000,000.0	10,400,000	15,000,000.0	10,400,000
OTHER FINANCIAL ASSETS
Balance at Beginning of Period	1,100,000	1,200,000	1,000,000.0	800,000
Charge-Offs	0	0	0	0
Recoveries	0	0	0	0
Net Recoveries (Charge-Offs)	0	0	0	0
Provision for Credit Losses	(400,000)	(200,000)	(300,000)	200,000
Balance at End of Period	700,000	1,000,000.0	700,000	1,000,000.0
TOTAL
Balance at Beginning of Period	198,200,000	207,000,000.0	184,700,000	259,900,000
Charge-Offs	(5,400,000)	0	(5,500,000)	(400,000)
Recoveries	900,000	1,100,000	9,700,000	5,600,000
Net Recoveries (Charge-Offs)	(4,500,000)	1,100,000	4,200,000	5,200,000
Provision for credit losses	1,400,000	(13,000,000.0)	6,200,000	(70,000,000.0)
Balance at End of Period	195,100,000	195,100,000	195,100,000	195,100,000
Corporate Debt
HELD TO MATURITY DEBT SECURITIES
Balance at Beginning of Period	1,800,000	1,600,000	1,400,000	800,000
Provision for Credit Losses	(300,000)	(200,000)	100,000	600,000
Balance at End of Period	1,500,000	1,400,000	1,500,000	1,400,000
TOTAL
Provision for credit losses	$ (900,000)	$ 0	$ 800,000	$ 0