Bank Loans and Related Allowance for Credit Losses (Composition of Bank Loans and Delinquency Analysis by Loan Segment) (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	$ 37,235,000,000	$ 34,654,000,000
Allowance for credit losses	28,000,000	18,000,000	$ 18,000,000	$ 30,000,000
Total bank loans – net	37,207,000,000	34,636,000,000
Loans accruing interest contractually 90 days or more past due	0	0
Current [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	37,168,000,000	34,564,000,000
Total Past Due And Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	67,000,000	90,000,000
30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	29,000,000	46,000,000
60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	8,000,000	9,000,000
More Than 90 Days Past Due and Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	30,000,000	35,000,000
Residential Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	23,307,000,000	21,738,000,000
Allowance for credit losses	25,000,000	15,000,000	15,000,000	27,000,000
Total bank loans – net	23,282,000,000	21,723,000,000
Residential Real Estate [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	23,260,000,000	21,659,000,000
Residential Real Estate [Member] | Total Past Due And Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	47,000,000	79,000,000
Residential Real Estate [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	17,000,000	43,000,000
Residential Real Estate [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	0	1,000,000
Residential Real Estate [Member] | More Than 90 Days Past Due and Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	30,000,000	35,000,000
First Mortgage [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	22,691,000,000	21,090,000,000
First Mortgage [Member] | Residential Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	22,691,000,000	21,090,000,000
Allowance for credit losses	23,000,000	13,000,000	12,000,000	22,000,000
Total bank loans – net	22,668,000,000	21,077,000,000
First Mortgage [Member] | Residential Real Estate [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	22,653,000,000	21,022,000,000
First Mortgage [Member] | Residential Real Estate [Member] | Total Past Due And Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	38,000,000	68,000,000
First Mortgage [Member] | Residential Real Estate [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	15,000,000	41,000,000
First Mortgage [Member] | Residential Real Estate [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	0	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	23,000,000	26,000,000
HELOCs [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	616,000,000	648,000,000
HELOCs [Member] | Residential Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	616,000,000	648,000,000
Allowance for credit losses	2,000,000	2,000,000	3,000,000	5,000,000
Total bank loans – net	614,000,000	646,000,000
HELOCs [Member] | Residential Real Estate [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	607,000,000	637,000,000
HELOCs [Member] | Residential Real Estate [Member] | Total Past Due And Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	9,000,000	11,000,000
HELOCs [Member] | Residential Real Estate [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	2,000,000	2,000,000
HELOCs [Member] | Residential Real Estate [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	0	0
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	7,000,000	9,000,000
Pledged asset lines [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	13,716,000,000	12,709,000,000
Allowance for credit losses	0	0
Total bank loans – net	13,716,000,000	12,709,000,000
Pledged asset lines [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	13,696,000,000	12,698,000,000
Pledged asset lines [Member] | Total Past Due And Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	20,000,000	11,000,000
Pledged asset lines [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	12,000,000	3,000,000
Pledged asset lines [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	8,000,000	8,000,000
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	212,000,000	207,000,000
Allowance for credit losses	3,000,000	3,000,000	$ 3,000,000	$ 3,000,000
Total bank loans – net	209,000,000	204,000,000
Other [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Total nonperforming assets	212,000,000	207,000,000
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 HELOC [Member]
Financing Receivable, Past Due [Line Items]
Unamortized premiums and discounts and direct origination costs	$ 94,000,000	$ 91,000,000
First Mortgage and HELOC [Member] | Loans Geographic Area [Member] | California [Member] | Geographic Concentration Risk [Member]
Financing Receivable, Past Due [Line Items]
Concentration risk percentage	45.00%	46.00%