Bank Loans and Related Allowance for Loan Losses (Changes in Allowance for Loan Losses) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of year	$ 21	$ 26	$ 26
Charge-offs	0	(1)	(3)
Recoveries	2	2	3
Provision for loan losses	(5)	(6)	0
Balance at end of year	18	21	26
First Mortgage [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of year	14	16	17
Charge-offs	0	0	(2)
Recoveries	1	1	1
Provision for loan losses	(4)	(3)	0
Balance at end of year	11	14	16
HELOC's [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of year	5	8	8
Charge-offs	0	0	(1)
Recoveries	1	1	1
Provision for loan losses	(2)	(4)	0
Balance at end of year	4	5	8
Other [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of year	2	2	1
Charge-offs	0	(1)	0
Recoveries	0	0	1
Provision for loan losses	1	1	0
Balance at end of year	$ 3	$ 2	$ 2