Loans Held-for-Investment - Loan Quality Indicators (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans held-for-investment	$ 13,236	$ 13,408
Consumer loans
Financing Receivable, Credit Quality Indicator [Line Items]
2022	176	704
2021	707	433
2020	388	496
2019	452	209
2018	190	118
Prior	470	460
Revolving Loans Amortized Cost Basis	875	876
Revolving Loans Converted to Term Loans Amortized Cost Basis	83	72
Total	3,341	3,368	$ 4,109
Total loans held-for-investment	3,362	3,385
Consumer loans | Residential first mortgage loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans held-for-investment	1,499	1,536
Consumer loans | Residential first mortgage loans | Debt-to-Value Ratio, Greater Than 90 Percent
Financing Receivable, Credit Quality Indicator [Line Items]
2022	3	88
2021	88	74
2020	67	142
2019	129	53
2018	51	16
Prior	28	16
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	366	389
Consumer loans | Residential first mortgage loans | Debt-to-Value Ratio, 71-90
Financing Receivable, Credit Quality Indicator [Line Items]
2022	21	109
2021	107	78
2020	64	58
2019	51	29
2018	21	31
Prior	199	185
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	463	490
Consumer loans | Residential first mortgage loans | Debt-to-Vale Ratio, 55-70
Financing Receivable, Credit Quality Indicator [Line Items]
2022	69	69
2021	79	26
2020	23	27
2019	26	9
2018	8	36
Prior	131	163
Revolving Loans Amortized Cost Basis	2	2
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	338	332
Consumer loans | Residential first mortgage loans | Debt-to-Value Ratio, Less than 55
Financing Receivable, Credit Quality Indicator [Line Items]
2022	14	53
2021	67	23
2020	19	25
2019	23	9
2018	9	31
Prior	92	75
Revolving Loans Amortized Cost Basis	75	80
Revolving Loans Converted to Term Loans Amortized Cost Basis	13	14
Total	312	310
Consumer loans | Residential first mortgage loans | FICO Score, Greater than 750
Financing Receivable, Credit Quality Indicator [Line Items]
2022	18	139
2021	155	94
2020	78	107
2019	95	40
2018	37	70
Prior	246	212
Revolving Loans Amortized Cost Basis	46	49
Revolving Loans Converted to Term Loans Amortized Cost Basis	4	5
Total	679	716
Consumer loans | Residential first mortgage loans | FICO Score, 700 to 750
Financing Receivable, Credit Quality Indicator [Line Items]
2022	86	117
2021	121	58
2020	50	69
2019	62	36
2018	29	36
Prior	132	161
Revolving Loans Amortized Cost Basis	21	22
Revolving Loans Converted to Term Loans Amortized Cost Basis	6	6
Total	507	505
Consumer loans | Residential first mortgage loans | FICO Score, Less than 700
Financing Receivable, Credit Quality Indicator [Line Items]
2022	3	63
2021	65	49
2020	45	76
2019	72	24
2018	23	8
Prior	72	66
Revolving Loans Amortized Cost Basis	10	11
Revolving Loans Converted to Term Loans Amortized Cost Basis	3	3
Total	293	300
Consumer loans | Residential first mortgage loans | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2022	107	318
2021	340	197
2020	169	233
2019	204	89
2018	74	108
Prior	408	407
Revolving Loans Amortized Cost Basis	77	82
Revolving Loans Converted to Term Loans Amortized Cost Basis	10	10
Total	1,389	1,444	2,205
Consumer loans | Residential first mortgage loans | Watch
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	0	1
2020	1	12
2019	1	3
2018	3	4
Prior	4	11
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	3
Total	9	34	21
Consumer loans | Residential first mortgage loans | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	1
2021	1	3
2020	3	7
2019	24	8
2018	12	2
Prior	38	21
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	3	1
Total	81	43	25
Consumer loans | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans held-for-investment	596	613
Consumer loans | Home equity | Debt-to-Value Ratio, Greater Than 90 Percent
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	1	0
2020	0	0
2019	0	0
2018	0	1
Prior	6	7
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	1	0
Total	8	8
Consumer loans | Home equity | Debt-to-Value Ratio, 71-90
Financing Receivable, Credit Quality Indicator [Line Items]
2022	1	3
2021	2	3
2020	2	11
2019	9	4
2018	4	1
Prior	7	6
Revolving Loans Amortized Cost Basis	355	369
Revolving Loans Converted to Term Loans Amortized Cost Basis	41	35
Total	421	432
Consumer loans | Home equity | Debt-to-Value Ratio, Less than or Equal to 70
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	1
2021	1	1
2020	1	4
2019	3	2
2018	1	1
Prior	3	3
Revolving Loans Amortized Cost Basis	137	141
Revolving Loans Converted to Term Loans Amortized Cost Basis	20	18
Total	166	171
Consumer loans | Home equity | FICO Score, Greater than 750
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	2
2021	2	2
2020	1	4
2019	3	2
2018	2	1
Prior	4	4
Revolving Loans Amortized Cost Basis	234	238
Revolving Loans Converted to Term Loans Amortized Cost Basis	16	13
Total	262	266
Consumer loans | Home equity | FICO Score, 700 to 750
Financing Receivable, Credit Quality Indicator [Line Items]
2022	1	2
2021	2	1
2020	1	6
2019	5	2
2018	2	1
Prior	6	6
Revolving Loans Amortized Cost Basis	205	210
Revolving Loans Converted to Term Loans Amortized Cost Basis	26	22
Total	248	250
Consumer loans | Home equity | FICO Score, Less than 700
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	0	1
2020	1	5
2019	4	2
2018	1	1
Prior	6	6
Revolving Loans Amortized Cost Basis	53	62
Revolving Loans Converted to Term Loans Amortized Cost Basis	20	18
Total	85	95
Consumer loans | Home equity | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2022	1	4
2021	4	4
2020	3	15
2019	12	6
2018	5	3
Prior	15	15
Revolving Loans Amortized Cost Basis	490	508
Revolving Loans Converted to Term Loans Amortized Cost Basis	57	49
Total	587	604	838
Consumer loans | Home equity | Watch
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	0	0
2020	0	0
2019	0	0
2018	0	0
Prior	0	0
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	1	1
Total	1	1	13
Consumer loans | Home equity | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	0	0
2020	0	0
2019	0	0
2018	0	0
Prior	1	1
Revolving Loans Amortized Cost Basis	2	2
Revolving Loans Converted to Term Loans Amortized Cost Basis	4	3
Total	7	6	3
Consumer loans | Other consumer | FICO Score, Greater than 750
Financing Receivable, Credit Quality Indicator [Line Items]
2022	68	251
2021	362	162
2020	212	142
2019	211	56
2018	96	1
Prior	4	4
Revolving Loans Amortized Cost Basis	203	273
Revolving Loans Converted to Term Loans Amortized Cost Basis	5	3
Total	1,161	892
Consumer loans | Other consumer | FICO Score, 700 to 750
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	128
2021	0	62
2020	0	79
2019	0	39
2018	0	0
Prior	0	1
Revolving Loans Amortized Cost Basis	84	7
Revolving Loans Converted to Term Loans Amortized Cost Basis	2	0
Total	86	316
Consumer loans | Other consumer | FICO Score, Less than 700
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	2
2021	0	4
2020	0	8
2019	0	8
2018	0	0
Prior	0	0
Revolving Loans Amortized Cost Basis	19	4
Revolving Loans Converted to Term Loans Amortized Cost Basis	1	2
Total	20	28
Consumer loans | Other consumer | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2022	68	380
2021	362	227
2020	211	226
2019	209	101
2018	95	1
Prior	4	5
Revolving Loans Amortized Cost Basis	306	284
Revolving Loans Converted to Term Loans Amortized Cost Basis	8	5
Total	1,263	1,229	1,000
Consumer loans | Other consumer | Watch
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	0	0
2020	0	1
2019	1	1
2018	0	0
Prior	0	0
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	1	2	1
Consumer loans | Other consumer | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	1
2021	0	1
2020	1	2
2019	1	1
2018	1	0
Prior	0	0
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total	3	5	3
Consumer loans | Residential first mortgage and home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2022	108	323
2021	345	205
2020	176	267
2019	241	106
2018	94	117
Prior	466	455
Revolving Loans Amortized Cost Basis	569	592
Revolving Loans Converted to Term Loans Amortized Cost Basis	75	67
Total	2,074	2,132
Commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
2022	4,711	5,755
2021	824	347
2020	350	744
2019	603	383
2018	356	421
Prior	833	444
Revolving Loans Amortized Cost Basis	2,197	1,929
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total loans held-for-investment	9,874	10,023	12,101
Commercial loans | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans held-for-investment	3,254	3,223
Commercial loans | Commercial real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2022	63	518
2021	546	257
2020	256	558
2019	437	313
2018	290	238
Prior	633	402
Revolving Loans Amortized Cost Basis	869	785
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total loans held-for-investment	3,094	3,071	2,805
Commercial loans | Commercial real estate | Watch
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	2
2021	0	5
2020	7	1
2019	1	13
2018	13	64
Prior	83	35
Revolving Loans Amortized Cost Basis	32	8
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total loans held-for-investment	136	128	166
Commercial loans | Commercial real estate | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	0	0
2020	0	2
2019	2	0
2018	0	0
Prior	22	0
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total loans held-for-investment	24	2	53
Commercial loans | Commercial real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	0	0
2020	0	0
2019	0	0
2018	0	22
Prior	0	0
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total loans held-for-investment	0	22	37
Commercial loans | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Total loans held-for-investment	1,979	1,826
Commercial loans | Commercial and industrial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2022	7	257
2021	265	81
2020	75	156
2019	163	30
2018	26	95
Prior	93	7
Revolving Loans Amortized Cost Basis	1,254	1,059
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total loans held-for-investment	1,883	1,685	1,200
Commercial loans | Commercial and industrial | Watch
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	4
2021	4	4
2020	12	10
2019	0	9
2018	9	0
Prior	0	0
Revolving Loans Amortized Cost Basis	14	44
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total loans held-for-investment	39	71	106
Commercial loans | Commercial and industrial | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	9	0
2020	0	0
2019	0	0
2018	0	0
Prior	0	0
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total loans held-for-investment	9	0	24
Commercial loans | Commercial and industrial | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	0	0
2020	0	17
2019	0	18
2018	18	2
Prior	2	0
Revolving Loans Amortized Cost Basis	28	33
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total loans held-for-investment	48	70	52
Commercial loans | Warehouse loan commitments | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2022	4,496	4,834
2021	0	0
2020	0	0
2019	0	0
2018	0	0
Prior	0	0
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total loans held-for-investment	4,496	4,834	7,398
Commercial loans | Warehouse loan commitments | Watch
Financing Receivable, Credit Quality Indicator [Line Items]
2022	145	140
2021	0	0
2020	0	0
2019	0	0
2018	0	0
Prior	0	0
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total loans held-for-investment	145	140	260
Commercial loans | Warehouse loan commitments | Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	0	0
2020	0	0
2019	0	0
2018	0	0
Prior	0	0
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total loans held-for-investment	0	0	0
Commercial loans | Warehouse loan commitments | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0	0
2021	0	0
2020	0	0
2019	0	0
2018	0	0
Prior	0	0
Revolving Loans Amortized Cost Basis	0	0
Revolving Loans Converted to Term Loans Amortized Cost Basis	0	0
Total loans held-for-investment	$ 0	$ 0	$ 0