Allowance for Credit Losses (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021	Dec. 31, 2020
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Provision for credit losses	$ 1,400,000	$ (13,000,000.0)	$ 6,200,000	$ (70,000,000.0)
Credit loss expense (reversal) and available-for-sale, allowance for credit loss	500,000	(13,000,000.0)	7,000,000.0	(70,000,000.0)
Net recoveries (charge-offs)	4,500,000	(1,100,000)	$ (4,200,000)	(5,200,000)
Time period used for projecting future conditions to estimate credit losses			2 years
Other financial assets, allowance for credit loss	700,000	1,000,000.0	$ 700,000	1,000,000.0	$ 1,100,000	$ 1,000,000.0	$ 1,200,000	$ 800,000
Corporate Debt
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Provision for credit losses	$ (900,000)	$ 0	$ 800,000	$ 0