Bank Loans and Related Allowance for Credit Losses (Narrative) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accrued interest	$ 144	$ 134
Residential Real Estate [Member] | First Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Bank loans	$ 21,100
Percent of loans with interest-only payments	27.00%
Percent of interest only adjustable rate	91.00%
Total bank loans	$ 25,806	25,198
Residential Real Estate [Member] | First Mortgage [Member] | Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fixed rate interest rate period	3 years
Interest-only reset period	3 years
Residential Real Estate [Member] | First Mortgage [Member] | Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fixed rate interest rate period	10 years
Residential Real Estate [Member] | HELOCs [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan term	30 years
Initial draw period	10 years
Converting to amortizing loans period	20 years
Total bank loans	$ 513	$ 597
Percent of loan balance outstanding, borrowers paid only minimum due	57.00%
Residential Real Estate [Member] | Home Equity Secured By Second Liens [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total bank loans	$ 404