Bank Loans and Related Allowance for Credit Losses (Composition of Bank Loans and Delinquency Analysis by Loan Segment) (Details) - USD ($)		6 Months Ended	12 Months Ended
		Jun. 30, 2023	Dec. 31, 2022	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021
Financing Receivable, Past Due [Line Items]
Total loans		$ 40,136,000,000	$ 40,578,000,000
Allowance for credit losses		75,000,000	73,000,000	$ 74,000,000	$ 37,000,000	$ 28,000,000	$ 18,000,000
Total bank loans – net	[1]	40,061,000,000	40,505,000,000
Loans accruing interest contractually 90 days or more past due		0	0
Current [Member]
Financing Receivable, Past Due [Line Items]
Total loans		40,101,000,000	40,522,000,000
Total Past Due And Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total loans		35,000,000	56,000,000
30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		18,000,000	31,000,000
60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		2,000,000	2,000,000
More Than 90 Days Past Due and Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total loans		15,000,000	23,000,000
Residential Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Total loans		26,319,000,000	25,795,000,000
Allowance for credit losses		71,000,000	70,000,000	71,000,000	34,000,000	25,000,000	15,000,000
Total bank loans – net		26,248,000,000	25,725,000,000
Unamortized premiums and discounts and direct origination costs		$ 99,000,000	$ 98,000,000
Residential Real Estate [Member] | Loans Geographic Area [Member] | California [Member] | Geographic Concentration Risk [Member]
Financing Receivable, Past Due [Line Items]
Concentration risk percentage		43.00%	43.00%
Residential Real Estate [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Total loans		$ 26,290,000,000	$ 25,747,000,000
Residential Real Estate [Member] | Total Past Due And Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total loans		29,000,000	48,000,000
Residential Real Estate [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		12,000,000	27,000,000
Residential Real Estate [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		2,000,000	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 loans		15,000,000	19,000,000
Residential Real Estate [Member] | First Mortgage [Member]
Financing Receivable, Past Due [Line Items]
Total loans		25,806,000,000	25,198,000,000
Allowance for credit losses		68,000,000	66,000,000	67,000,000	31,000,000	23,000,000	13,000,000
Total bank loans – net		25,738,000,000	25,132,000,000
Residential Real Estate [Member] | First Mortgage [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Total loans		25,783,000,000	25,157,000,000
Residential Real Estate [Member] | First Mortgage [Member] | Total Past Due And Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total loans		23,000,000	41,000,000
Residential Real Estate [Member] | First Mortgage [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		12,000,000	25,000,000
Residential Real Estate [Member] | First Mortgage [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		1,000,000	2,000,000
Residential Real Estate [Member] | First Mortgage [Member] | More Than 90 Days Past Due and Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total loans		10,000,000	14,000,000
Residential Real Estate [Member] | HELOCs [Member]
Financing Receivable, Past Due [Line Items]
Total loans		513,000,000	597,000,000
Allowance for credit losses		3,000,000	4,000,000	4,000,000	3,000,000	2,000,000	2,000,000
Total bank loans – net		510,000,000	593,000,000
Residential Real Estate [Member] | HELOCs [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Total loans		507,000,000	590,000,000
Residential Real Estate [Member] | HELOCs [Member] | Total Past Due And Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total loans		6,000,000	7,000,000
Residential Real Estate [Member] | HELOCs [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		0	2,000,000
Residential Real Estate [Member] | HELOCs [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		1,000,000	0
Residential Real Estate [Member] | HELOCs [Member] | More Than 90 Days Past Due and Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total loans		5,000,000	5,000,000
Pledged asset lines [Member]
Financing Receivable, Past Due [Line Items]
Total loans		13,572,000,000	14,592,000,000
Allowance for credit losses		0	0	0	0	0	0
Total bank loans – net		13,572,000,000	14,592,000,000
Pledged asset lines [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Total loans		13,566,000,000	14,584,000,000
Pledged asset lines [Member] | Total Past Due And Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total loans		6,000,000	8,000,000
Pledged asset lines [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		6,000,000	4,000,000
Pledged asset lines [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		0	0
Pledged asset lines [Member] | More Than 90 Days Past Due and Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total loans		0	4,000,000
Other [Member]
Financing Receivable, Past Due [Line Items]
Total loans		245,000,000	191,000,000
Allowance for credit losses		4,000,000	3,000,000	$ 3,000,000	$ 3,000,000	$ 3,000,000	$ 3,000,000
Total bank loans – net		241,000,000	188,000,000
Other [Member] | Current [Member]
Financing Receivable, Past Due [Line Items]
Total loans		245,000,000	191,000,000
Other [Member] | Total Past Due And Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total loans		0	0
Other [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		0	0
Other [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total loans		0	0
Other [Member] | More Than 90 Days Past Due and Other Nonaccrual Loans [Member]
Financing Receivable, Past Due [Line Items]
Total loans		$ 0	$ 0

[1] Certain prior year amounts have been reclassified to conform to the current year presentation. See Note 1 for additional information.