Bank Loans and Related Allowance for Credit Losses (Credit Quality Indicators of Bank Loan Portfolio) (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	$ 40,428	$ 34,654
First Mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2022	5,594
2021	12,465	12,990
2020	4,346	5,004
2019	950	1,200
2018	146	207
pre-2018	1,193	1,689
Total loans	$ 24,694	$ 21,090
Percent of Loans on Nonaccrual Status
2022	0.01%
2021	0.02%	0.03%
2020	0.07%	0.10%
2019	0.03%	0.03%
2018	0.33%	0.03%
pre-2018	0.46%	1.03%
Total loans	0.05%	0.12%
First Mortgage [Member] | Financial Asset Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2022	$ 5,594
2021	12,465	$ 12,990
2020	4,346	5,004
2019	950	1,200
2018	146	207
pre-2018	1,193	1,689
Total loans	24,694	21,090
First Mortgage [Member] | Origination Loan to Value Ratio 70% and Below [Member] | Financial Asset Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2022	4,195
2021	10,782	11,234
2020	3,607	4,159
2019	765	948
2018	113	160
pre-2018	884	1,260
Total loans	20,346	17,761
First Mortgage [Member] | Origination Loan to Value Ratio Greater Than 70% Through 90% [Member] | Financial Asset Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2022	1,399
2021	1,683	1,756
2020	739	845
2019	185	252
2018	33	47
pre-2018	307	426
Total loans	4,346	3,326
First Mortgage [Member] | Origination Loan to Value Ratio Greater Than 90% Through 100% [Member] | Financial Asset Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	0	0
2020	0	0
2019	0	0
2018	0	0
pre-2018	2	3
Total loans	2	3
First Mortgage [Member] | Estimated Current Loan To Value Ratio 70% and Below [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2022	4,331
2021	12,196	11,707
2020	4,336	4,961
2019	950	1,196
2018	146	206
pre-2018	1,189	1,684
Total loans	23,148	19,754
First Mortgage [Member] | Estimated Current Loan To Value Ratio Greater Than 70% Through 90% [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2022	1,263
2021	269	1,283
2020	10	43
2019	0	4
2018	0	1
pre-2018	4	5
Total loans	1,546	1,336
First Mortgage [Member] | Estimated Current LTV Greater Than 90% Through 100% [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	0	0
2020	0	0
2019	0	0
2018	0	0
pre-2018	0	0
Total loans	0	0
First Mortgage [Member] | Estimated Current LTV Greater Than 100% [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	0	0
2020	0	0
2019	0	0
2018	0	0
pre-2018	0	0
Total loans	0	0
First Mortgage [Member] | Origination FICO Score Below 620 [Member] | Financial Asset Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2022	2
2021	1	1
2020	1	1
2019	0	0
2018	0	0
pre-2018	1	1
Total loans	5	3
First Mortgage [Member] | Origination FICO Score 620 Through 679 [Member] | Financial Asset Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2022	27
2021	32	34
2020	21	25
2019	2	5
2018	1	1
pre-2018	14	25
Total loans	97	90
First Mortgage [Member] | Origination FICO Score 680 Through 739 [Member] | Financial Asset Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2022	708
2021	1,246	1,306
2020	434	524
2019	119	146
2018	30	41
pre-2018	222	313
Total loans	2,759	2,330
First Mortgage [Member] | Origination FICO Score 740 and Above [Member] | Financial Asset Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2022	4,857
2021	11,186	11,649
2020	3,890	4,454
2019	829	1,049
2018	115	165
pre-2018	956	1,350
Total loans	21,833	18,667
First Mortgage [Member] | Updated FICO Score Below 620 [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2022	8
2021	8	5
2020	6	2
2019	3	1
2018	3	0
pre-2018	10	14
Total loans	38	22
First Mortgage [Member] | Updated FICO Score 620 Through 679 [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2022	74
2021	102	96
2020	41	69
2019	9	19
2018	3	7
pre-2018	32	38
Total loans	261	229
First Mortgage [Member] | Updated FICO Score 680 Through 739 [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2022	624
2021	994	1,265
2020	339	421
2019	90	115
2018	20	24
pre-2018	157	202
Total loans	2,224	2,027
First Mortgage [Member] | Updated FICO Score 740 and Above [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2022	4,888
2021	11,361	11,624
2020	3,960	4,512
2019	848	1,065
2018	120	176
pre-2018	994	1,435
Total loans	22,171	18,812
HELOCs [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving HELOCs amortized cost basis	384	369
HELOCs converted to term loans	226	279
Total loans	$ 610	$ 648
Percent of Loans on Nonaccrual Status
Revolving HELOCs amortized cost basis	0.31%	0.64%
HELOCs converted to term loans	1.63%	2.33%
Total loans	0.82%	1.39%
HELOCs [Member] | Financial Asset Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving HELOCs amortized cost basis	$ 384	$ 369
HELOCs converted to term loans	226	279
Total loans	610	648
HELOCs [Member] | Origination Loan to Value Ratio 70% and Below [Member] | Financial Asset Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving HELOCs amortized cost basis	329	305
HELOCs converted to term loans	161	199
Total loans	490	504
HELOCs [Member] | Origination Loan to Value Ratio Greater Than 70% Through 90% [Member] | Financial Asset Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving HELOCs amortized cost basis	55	64
HELOCs converted to term loans	64	78
Total loans	119	142
HELOCs [Member] | Origination Loan to Value Ratio Greater Than 90% Through 100% [Member] | Financial Asset Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving HELOCs amortized cost basis	0	0
HELOCs converted to term loans	1	2
Total loans	1	2
HELOCs [Member] | Estimated Current Loan To Value Ratio 70% and Below [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving HELOCs amortized cost basis	382	368
HELOCs converted to term loans	225	277
Total loans	607	645
HELOCs [Member] | Estimated Current Loan To Value Ratio Greater Than 70% Through 90% [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving HELOCs amortized cost basis	2	1
HELOCs converted to term loans	1	2
Total loans	3	3
HELOCs [Member] | Estimated Current LTV Greater Than 90% Through 100% [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving HELOCs amortized cost basis	0	0
HELOCs converted to term loans	0	0
Total loans	0	0
HELOCs [Member] | Estimated Current LTV Greater Than 100% [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving HELOCs amortized cost basis	0	0
HELOCs converted to term loans	0	0
Total loans	0	0
HELOCs [Member] | Origination FICO Score Below 620 [Member] | Financial Asset Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving HELOCs amortized cost basis	0	0
HELOCs converted to term loans	0	0
Total loans	0	0
HELOCs [Member] | Origination FICO Score 620 Through 679 [Member] | Financial Asset Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving HELOCs amortized cost basis	0	0
HELOCs converted to term loans	2	2
Total loans	2	2
HELOCs [Member] | Origination FICO Score 680 Through 739 [Member] | Financial Asset Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving HELOCs amortized cost basis	60	61
HELOCs converted to term loans	50	60
Total loans	110	121
HELOCs [Member] | Origination FICO Score 740 and Above [Member] | Financial Asset Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving HELOCs amortized cost basis	324	308
HELOCs converted to term loans	174	217
Total loans	498	525
HELOCs [Member] | Updated FICO Score Below 620 [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving HELOCs amortized cost basis	2	2
HELOCs converted to term loans	5	6
Total loans	7	8
HELOCs [Member] | Updated FICO Score 620 Through 679 [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving HELOCs amortized cost basis	7	6
HELOCs converted to term loans	12	14
Total loans	19	20
HELOCs [Member] | Updated FICO Score 680 Through 739 [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving HELOCs amortized cost basis	48	51
HELOCs converted to term loans	31	39
Total loans	79	90
HELOCs [Member] | Updated FICO Score 740 and Above [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving HELOCs amortized cost basis	327	310
HELOCs converted to term loans	178	220
Total loans	$ 505	$ 530