Bank Loans and Related Allowance for Credit Losses (Composition of Bank Loans and Delinquency Analysis by Loan Segment) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	$ 34,654,000,000	$ 23,843,000,000
Allowance for credit losses	18,000,000	30,000,000	$ 18,000,000	$ 21,000,000
Total bank loans – net	34,636,000,000	23,813,000,000
Loans accruing interest contractually 90 days or more past due	0	0
Current [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	34,564,000,000	23,709,000,000
Total Past Due And Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	90,000,000	134,000,000
30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	46,000,000	38,000,000
60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	9,000,000	7,000,000
More Than 90 Days Past Due and Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	35,000,000	89,000,000
Residential Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	21,738,000,000	15,746,000,000
Allowance for credit losses	15,000,000	27,000,000	15,000,000	19,000,000
Total bank loans – net	21,723,000,000	15,719,000,000
Residential Real Estate [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	21,659,000,000	15,627,000,000
Residential Real Estate [Member] | Total Past Due And Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	79,000,000	119,000,000
Residential Real Estate [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	43,000,000	28,000,000
Residential Real Estate [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	1,000,000	2,000,000
Residential Real Estate [Member] | More Than 90 Days Past Due and Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	35,000,000	89,000,000
First Mortgage [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	21,090,000,000	14,904,000,000
First Mortgage [Member] | Residential Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	21,090,000,000	14,904,000,000
Allowance for credit losses	13,000,000	22,000,000	11,000,000	14,000,000
Total bank loans – net	21,077,000,000	14,882,000,000
First Mortgage [Member] | Residential Real Estate [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	21,022,000,000	14,804,000,000
First Mortgage [Member] | Residential Real Estate [Member] | Total Past Due And Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	68,000,000	100,000,000
First Mortgage [Member] | Residential Real Estate [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	41,000,000	27,000,000
First Mortgage [Member] | Residential Real Estate [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	1,000,000	1,000,000
First Mortgage [Member] | Residential Real Estate [Member] | More Than 90 Days Past Due and Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	26,000,000	72,000,000
HELOCs [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	648,000,000	842,000,000
HELOCs [Member] | Residential Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	648,000,000	842,000,000
Allowance for credit losses	2,000,000	5,000,000	4,000,000	5,000,000
Total bank loans – net	646,000,000	837,000,000
HELOCs [Member] | Residential Real Estate [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	637,000,000	823,000,000
HELOCs [Member] | Residential Real Estate [Member] | Total Past Due And Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	11,000,000	19,000,000
HELOCs [Member] | Residential Real Estate [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	2,000,000	1,000,000
HELOCs [Member] | Residential Real Estate [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	0	1,000,000
HELOCs [Member] | Residential Real Estate [Member] | More Than 90 Days Past Due and Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	9,000,000	17,000,000
Pledged asset lines [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	12,709,000,000	7,916,000,000
Allowance for credit losses	0	0
Total bank loans – net	12,709,000,000	7,916,000,000
Pledged asset lines [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	12,698,000,000	7,901,000,000
Pledged asset lines [Member] | Total Past Due And Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	11,000,000	15,000,000
Pledged asset lines [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	3,000,000	10,000,000
Pledged asset lines [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	8,000,000	5,000,000
Pledged asset lines [Member] | More Than 90 Days Past Due and Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	0	0
Other [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	207,000,000	181,000,000
Allowance for credit losses	3,000,000	3,000,000	$ 3,000,000	$ 2,000,000
Total bank loans – net	204,000,000	178,000,000
Other [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	207,000,000	181,000,000
Other [Member] | Total Past Due And Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	0	0
Other [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	0	0
Other [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	0	0
Other [Member] | More Than 90 Days Past Due and Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	0	0
First Mortgage And Home Equity [Member]
Financing Receivable, Past Due [Line Items]
Unamortized premiums and discounts and direct origination costs	$ 91,000,000	$ 72,000,000
First Mortgage And Home Equity [Member] | Loans Geographic Area [Member] | California [Member] | Geographic Concentration Risk [Member]
Financing Receivable, Past Due [Line Items]
Concentration risk percentage	46.00%	45.00%