Bank Loans and Related Allowance for Loan Losses (Convert to Amortizing Loans) (Details) - HELOC's [Member] $ in Millions	Dec. 31, 2019 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Converted to an amortizing loan by period end	$ 506
Within 1 year	45
1 year – 3 years	81
3 years – 5 years	155
5 years	330
Total	$ 1,117