Bank Loans and Related Allowance for Credit Losses (Changes in Allowance for Credit Losses) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 74	$ 28	$ 73	$ 18
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision for credit losses	1	9	2	19
Balance at end of period	75	37	75	37
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	71	25	70	15
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision for credit losses	0	9	1	19
Balance at end of period	71	34	71	34
Residential Real Estate [Member] | First Mortgage [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	67	23	66	13
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision for credit losses	1	8	2	18
Balance at end of period	68	31	68	31
Residential Real Estate [Member] | HELOCs [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	4	2	4	2
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision for credit losses	(1)	1	(1)	1
Balance at end of period	3	3	3	3
Pledged asset lines [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	0	0	0	0
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision for credit losses	0	0	0	0
Balance at end of period	0	0	0	0
Other [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	3	3	3	3
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision for credit losses	1	0	1	0
Balance at end of period	$ 4	$ 3	$ 4	$ 3