Bank Loans and Related Allowance for Credit Losses (Convert to Amortizing Loans) (Details) - HELOCs [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
HELOCs converted to amortizing loans	$ 8	$ 11	$ 18	$ 33
Converted to an amortizing loan by period end	446		446
Within 1 year	41		41
1 year – 3 years	86		86
3 years – 5 years	124		124
5 years	284		284
Total	$ 981		$ 981