Bank Loans and Related Allowance for Credit Losses (Convert to Amortizing Loans) (Details) - HELOC's [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
HELOCs converted to amortizing loans	$ 26	$ 44
Converted to an amortizing loan by period end	379
Within 1 year	31
> 1 year – 3 years	88
> 3 years – 5 years	95
> 5 years	249
Total	$ 842