Bank Loans and Related Allowance for Credit Losses (Credit Quality Indicators of Bank Loan Portfolio) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans	$ 34,654	$ 23,843
First Mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	12,990
2020	5,004	7,974
2019	1,200	2,820
2018	207	557
2017	458	1,047
pre-2017	1,231	2,506
Total loans	$ 21,090	$ 14,904
Percent of Loans on Nonaccrual Status
2021	0.03%
2020	0.10%	0.09%
2019	0.03%	0.38%
2018	0.03%	1.02%
2017	0.03%	0.87%
pre-2017	1.40%	1.57%
Total loans	0.12%	0.48%
First Mortgage [Member] | Financial Asset Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	$ 12,990
2020	5,004	$ 7,974
2019	1,200	2,820
2018	207	557
2017	458	1,047
pre-2017	1,231	2,506
Total loans	21,090	14,904
First Mortgage [Member] | Origination Loan To Value Ratio 70% And Below [Member] | Financial Asset Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	11,234
2020	4,159	6,653
2019	948	2,211
2018	160	396
2017	351	793
pre-2017	909	1,935
Total loans	17,761	11,988
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]
2021	1,756
2020	845	1,321
2019	252	609
2018	47	161
2017	107	254
pre-2017	319	568
Total loans	3,326	2,913
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]
2021	0
2020	0	0
2019	0	0
2018	0	0
2017	0	0
pre-2017	3	3
Total loans	3	3
First Mortgage [Member] | Estimated Current LTV 70% And Below [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	11,707
2020	4,961	6,999
2019	1,196	2,582
2018	206	533
2017	455	1,034
pre-2017	1,229	2,490
Total loans	19,754	13,638
First Mortgage [Member] | Estimated Current LTV Greater Than 70% through 90% [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	1,283
2020	43	975
2019	4	238
2018	1	24
2017	3	13
pre-2017	2	16
Total loans	1,336	1,266
First Mortgage [Member] | Estimated Current LTV Greater Than 90% through 100% [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0
2020	0	0
2019	0	0
2018	0	0
2017	0	0
pre-2017	0	0
Total loans	0	0
First Mortgage [Member] | Estimated Current LTV Greater Than 100% [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0
2020	0	0
2019	0	0
2018	0	0
2017	0	0
pre-2017	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]
2021	1
2020	1	1
2019	0	0
2018	0	0
2017	0	0
pre-2017	1	2
Total loans	3	3
First Mortgage [Member] | Origination FICO Score 620 Through 679 [Member] | Financial Asset Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	34
2020	25	29
2019	5	13
2018	1	3
2017	6	8
pre-2017	19	31
Total loans	90	84
First Mortgage [Member] | Origination FICO Score 680 Through 739 [Member] | Financial Asset Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	1,306
2020	524	794
2019	146	355
2018	41	105
2017	98	181
pre-2017	215	419
Total loans	2,330	1,854
First Mortgage [Member] | Origination FICO Score 740 And Above [Member] | Financial Asset Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	11,649
2020	4,454	7,150
2019	1,049	2,452
2018	165	449
2017	354	858
pre-2017	996	2,054
Total loans	18,667	12,963
First Mortgage [Member] | Weighted Average Updated FICO Score Below 620 [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	5
2020	2	5
2019	1	2
2018	0	1
2017	2	4
pre-2017	12	19
Total loans	22	31
First Mortgage [Member] | Wighted Average Updated FICO Score 620 Through 679 [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	96
2020	69	67
2019	19	34
2018	7	16
2017	8	21
pre-2017	30	60
Total loans	229	198
First Mortgage [Member] | Weighted Average Updated FICO Score 680 Through 739 [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	1,265
2020	421	784
2019	115	252
2018	24	66
2017	53	121
pre-2017	149	281
Total loans	2,027	1,504
First Mortgage [Member] | Weighted Average Updated FICO Score 740 and Above [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	11,624
2020	4,512	7,118
2019	1,065	2,532
2018	176	474
2017	395	901
pre-2017	1,040	2,146
Total loans	18,812	13,171
HELOCs [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving HELOCs amortized cost basis	369	463
HELOCs converted to term loans	279	379
Total loans	$ 648	$ 842
Percent of Loans on Nonaccrual Status
Revolving HELOCs amortized cost basis	0.64%	1.37%
HELOCs converted to term loans	2.33%	2.80%
Total loans	1.39%	2.02%
HELOCs [Member] | Financial Asset Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving HELOCs amortized cost basis	$ 369	$ 463
HELOCs converted to term loans	279	379
Total loans	648	842
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	305	351
HELOCs converted to term loans	199	269
Total loans	504	620
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	64	112
HELOCs converted to term loans	78	107
Total loans	142	219
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	2	3
Total loans	2	3
HELOCs [Member] | Estimated Current LTV 70% And Below [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving HELOCs amortized cost basis	368	452
HELOCs converted to term loans	277	368
Total loans	645	820
HELOCs [Member] | Estimated Current LTV Greater Than 70% through 90% [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving HELOCs amortized cost basis	1	11
HELOCs converted to term loans	2	9
Total loans	3	20
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	1
Total loans	0	1
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	1
Total loans	0	1
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	1
HELOCs converted to term loans	2	3
Total loans	2	4
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	61	82
HELOCs converted to term loans	60	80
Total loans	121	162
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	308	380
HELOCs converted to term loans	217	296
Total loans	525	676
HELOCs [Member] | Weighted Average Updated FICO Score Below 620 [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving HELOCs amortized cost basis	2	3
HELOCs converted to term loans	6	9
Total loans	8	12
HELOCs [Member] | Wighted Average Updated FICO Score 620 Through 679 [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving HELOCs amortized cost basis	6	12
HELOCs converted to term loans	14	20
Total loans	20	32
HELOCs [Member] | Weighted Average Updated FICO Score 680 Through 739 [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving HELOCs amortized cost basis	51	58
HELOCs converted to term loans	39	55
Total loans	90	113
HELOCs [Member] | Weighted Average Updated FICO Score 740 and Above [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving HELOCs amortized cost basis	310	390
HELOCs converted to term loans	220	295
Total loans	$ 530	$ 685