Loans And Allowance For Credit Losses - Schedule of Company's Internal Ratings of its Loans Held-for-Investment, Including The Year of Origination, by Portfolio Segments (Detail) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Financing Receivable Recorded Investment [Line Items]
2022-2021	$ 3,094	$ 2,585
2021-2020	1,449	1,027
2020-2019	650	499
2019-2018	312	353
2018-2017	220	236
Prior	567	579
Revolving Loans Amort Cost Basis	150	110
Total Past Due	6,442	5,389
Agricultural [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	60	73
2021-2020	10	9
2020-2019	2	6
2019-2018	3	6
2018-2017	1	3
Prior	1	1
Total Past Due	77	98
Pass [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	3,054	2,548
2021-2020	1,430	1,005
2020-2019	637	471
2019-2018	285	332
2018-2017	208	217
Prior	531	548
Revolving Loans Amort Cost Basis	146	107
Total Past Due	6,291	5,228
Pass [Member] | Agricultural [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	60	69
2021-2020	9	8
2020-2019	2	6
2019-2018	3	6
2018-2017	1	3
Prior	1	1
Total Past Due	76	93
Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	7	12
2021-2020	5	8
2020-2019	6	17
2019-2018	20	1
2018-2017		9
Prior	11	7
Revolving Loans Amort Cost Basis	1	1
Total Past Due	50	55
Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	33	25
2021-2020	14	14
2020-2019	7	11
2019-2018	7	20
2018-2017	12	10
Prior	25	24
Revolving Loans Amort Cost Basis	3	2
Total Past Due	101	106
Substandard [Member] | Agricultural [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	0	4
2021-2020	1	1
Total Past Due	1	5
C&I [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	644	537
2021-2020	163	183
2020-2019	56	57
2019-2018	24	32
2018-2017	17	17
Prior	13	11
Total Past Due	917	837
C&I [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	627	526
2021-2020	157	178
2020-2019	52	52
2019-2018	22	29
2018-2017	16	17
Prior	13	11
Total Past Due	887	813
C&I [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	4	4
2021-2020	1	1
2020-2019	2	4
2019-2018	1
2018-2017	0
Total Past Due	8	9
C&I [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	13	7
2021-2020	5	4
2020-2019	2	1
2019-2018	1	3
2018-2017	1
Total Past Due	22	15
Muncipal [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	79	39
2021-2020	19	15
2020-2019	15	6
2019-2018	4	22
2018-2017	20	17
Prior	84	79
Total Past Due	221	178
Muncipal [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	79	39
2021-2020	19	15
2020-2019	15	6
2019-2018	4	22
2018-2017	20	17
Prior	84	79
Total Past Due	221	178
Construction & Development [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	643	561
2021-2020	219	136
2020-2019	70	24
2019-2018	13	14
2018-2017	8	7
Prior	7	8
Total Past Due	960	750
Construction & Development [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	638	557
2021-2020	218	134
2020-2019	70	24
2019-2018	13	14
2018-2017	8	7
Prior	7	8
Total Past Due	954	744
Construction & Development [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	1	2
2021-2020	0
Total Past Due	1	2
Construction & Development [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	4	2
2021-2020	1	2
Total Past Due	5	4
Farm [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	148	118
2021-2020	85	43
2020-2019	32	15
2019-2018	11	11
2018-2017	8	7
Prior	22	23
Total Past Due	306	217
Farm [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	147	117
2021-2020	85	42
2020-2019	32	15
2019-2018	11	10
2018-2017	8	7
Prior	21	23
Total Past Due	304	214
Farm [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	1	1
2021-2020	0	1
2019-2018	0	1
Prior	1
Total Past Due	2	3
Non - Owner Occupied CRE [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	266	214
2021-2020	193	130
2020-2019	102	92
2019-2018	62	57
2018-2017	22	41
Prior	87	90
Total Past Due	732	624
Non - Owner Occupied CRE [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	258	214
2021-2020	191	128
2020-2019	100	77
2019-2018	49	56
2018-2017	21	31
Prior	75	84
Total Past Due	694	590
Non - Owner Occupied CRE [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	0
2021-2020	1	1
2020-2019	1	12
2019-2018	11	0
2018-2017	0	7
Prior	7	3
Total Past Due	20	23
Non - Owner Occupied CRE [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	8
2021-2020	1	1
2020-2019	1	3
2019-2018	2	1
2018-2017	1	3
Prior	5	3
Total Past Due	18	11
Owner Occupied CRE [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	318	260
2021-2020	226	147
2020-2019	130	118
2019-2018	84	103
2018-2017	72	65
Prior	124	129
Total Past Due	954	822
Owner Occupied CRE [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	316	250
2021-2020	224	143
2020-2019	128	114
2019-2018	74	90
2018-2017	63	59
Prior	113	117
Total Past Due	918	773
Owner Occupied CRE [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	1	2
2021-2020	0	2
2020-2019	1	1
2019-2018	8
2018-2017	0	1
Prior	1	1
Total Past Due	11	7
Owner Occupied CRE [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	1	8
2021-2020	2	2
2020-2019	1	3
2019-2018	2	13
2018-2017	9	5
Prior	10	11
Total Past Due	25	42
Residential [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	520	483
2021-2020	361	237
2020-2019	177	118
2019-2018	84	87
2018-2017	65	71
Prior	226	235
Revolving Loans Amort Cost Basis	143	103
Total Past Due	1,576	1,334
Residential [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	513	477
2021-2020	355	230
2020-2019	173	115
2019-2018	82	84
2018-2017	64	68
Prior	214	222
Revolving Loans Amort Cost Basis	139	100
Total Past Due	1,540	1,296
Residential [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	1	3
2021-2020	3	4
2020-2019	2
2019-2018	0	1
2018-2017	0	1
Prior	3	3
Revolving Loans Amort Cost Basis	1	1
Total Past Due	10	13
Residential [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	6	3
2021-2020	3	3
2020-2019	2	3
2019-2018	2	2
2018-2017	1	2
Prior	9	10
Revolving Loans Amort Cost Basis	3	2
Total Past Due	26	25
Auto [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	331	219
2021-2020	131	105
2020-2019	56	55
2019-2018	25	17
2018-2017	6	7
Prior	2	2
Total Past Due	551	405
Auto [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	331	218
2021-2020	131	105
2020-2019	55	54
2019-2018	25	17
2018-2017	6	7
Prior	2	2
Total Past Due	550	403
Auto [Member] | Special Mention [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	0	1
2020-2019	0
Total Past Due	0	1
Auto [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
2020-2019	1	1
Total Past Due	1	1
Non - Auto [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	85	81
2021-2020	42	22
2020-2019	9	8
2019-2018	3	4
2018-2017	1	1
Prior	1	1
Revolving Loans Amort Cost Basis	7	7
Total Past Due	148	124
Non - Auto [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
2022-2021	85	81
2021-2020	41	22
2020-2019	9	8
2019-2018	3	4
2018-2017	1	1
Prior	1	1
Revolving Loans Amort Cost Basis	7	7
Total Past Due	147	$ 124
Non - Auto [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
2021-2020	1
Total Past Due	$ 1