Loans and Lease Finance Receivables and Allowance for Credit Losses - Summary of loans by type and origination year, according to our internal risk ratings (Detail) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2023	Dec. 31, 2022
Financing Receivable, Credit Quality Indicator [Line Items]
2023	$ 542,889	$ 1,683,162
2022	1,632,465	1,512,519
2021	1,438,370	1,178,645
2020	1,144,796	744,349
2019	685,020	633,929
Prior	2,560,933	2,265,644
Revolving loans amortized cost basis	817,251	1,002,474
Revolving loans converted to term loans	55,908	58,670
Total	8,877,632	9,079,392
Gross charge-off prior	224
Gross charge-off total	224
Commercial real estate loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	377,204	1,367,018
2022	1,339,962	1,209,404
2021	1,175,469	984,873
2020	952,006	592,100
2019	563,872	528,353
Prior	2,232,525	1,987,303
Revolving loans amortized cost basis	163,146	176,281
Revolving loans converted to term loans	38,875	39,616
Total	6,843,059	6,884,948
Construction [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	375	17,203
2022	14,984	26,689
2021	24,400	16,578
2020	8,062	0
2019		4,951
Prior	0	0
Revolving loans amortized cost basis	15,201	22,850
Revolving loans converted to term loans		0
Total	63,022	88,271
SBA [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	20,163	60,623
2022	50,643	54,781
2021	53,354	35,243
2020	34,387	8,781
2019	8,139	30,735
Prior	116,438	99,719
Revolving loans amortized cost basis		1,026
Revolving loans converted to term loans		0
Total	283,124	290,908
Gross charge-off prior	207
Gross charge-off total	207
SBA - Paycheck Protection Program (PPP) [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	0
2022		5,515
2021	809	3,572
2020	2,424	0
2019		0
Prior	0	0
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	0
Total	3,233	9,087
Commercial And Industrial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	124,308	159,214
2022	154,242	135,923
2021	109,090	81,950
2020	94,392	103,844
2019	78,331	48,817
Prior	108,377	85,910
Revolving loans amortized cost basis	256,354	323,945
Revolving loans converted to term loans	12,970	9,080
Total	938,064	948,683
Gross charge-off prior	16
Gross charge-off total	16
Dairy And Livestock And Agribusiness [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	710	1,248
2022	0	2,318
2021	2,074	1,555
2020	1,054	786
2019	181	210
Prior	413	741
Revolving loans amortized cost basis	345,692	419,199
Revolving loans converted to term loans	1,339	7,507
Total	351,463	433,564
Municipal Lease Finance Receivables [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	6,442
2022	5,989	26,858
2021	26,088	6,814
2020	6,188	4,327
2019	4,266	4,948
Prior	33,090	31,737
Revolving loans amortized cost basis		0
Revolving loans converted to term loans		0
Total	75,621	81,126
SFR mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	17,581	63,761
2022	61,882	46,748
2021	43,841	46,762
2020	45,453	33,585
2019	29,521	15,836
Prior	69,554	58,944
Revolving loans amortized cost basis		0
Revolving loans converted to term loans	339	388
Total	268,171	266,024
Consumer Other [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	2,548	7,653
2022	4,763	4,283
2021	3,245	1,298
2020	830	926
2019	710	79
Prior	536	1,290
Revolving loans amortized cost basis	36,858	59,173
Revolving loans converted to term loans	2,385	2,079
Total	51,875	76,781
Gross charge-off prior	1
Gross charge-off total	1
Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	530,758	1,674,387
2022	1,618,621	1,499,083
2021	1,420,519	1,149,567
2020	1,091,735	690,504
2019	622,713	599,162
Prior	2,435,905	2,163,284
Revolving loans amortized cost basis	741,775	963,645
Revolving loans converted to term loans	45,993	48,948
Total	8,508,019	8,788,580
Pass [Member] \| Commercial real estate loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	373,704	1,363,733
2022	1,327,377	1,197,290
2021	1,159,196	957,965
2020	900,512	542,827
2019	508,645	506,613
Prior	2,119,797	1,889,478
Revolving loans amortized cost basis	160,435	175,373
Revolving loans converted to term loans	38,875	39,616
Total	6,588,541	6,672,895
Pass [Member] \| Construction [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	375	17,203
2022	14,984	26,689
2021	24,400	16,578
2020	8,062	0
2019	0	0
Prior	0	0
Revolving loans amortized cost basis	15,201	22,850
Revolving loans converted to term loans		0
Total	63,022	83,320
Pass [Member] \| SBA [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	20,163	60,623
2022	50,643	54,781
2021	53,354	35,243
2020	34,387	7,460
2019	6,249	28,886
Prior	110,538	96,473
Revolving loans amortized cost basis		1,026
Revolving loans converted to term loans		0
Total	275,334	284,492
Pass [Member] \| SBA - Paycheck Protection Program (PPP) [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	0
2022		5,515
2021	809	3,572
2020	2,424	0
2019		0
Prior	0	0
Revolving loans amortized cost basis		0
Revolving loans converted to term loans		0
Total	3,233	9,087
Pass [Member] \| Commercial And Industrial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	116,890	154,765
2022	152,983	135,162
2021	107,790	80,763
2020	93,749	101,192
2019	73,760	42,731
Prior	102,963	85,406
Revolving loans amortized cost basis	248,769	305,589
Revolving loans converted to term loans	6,218	7,775
Total	903,122	913,383
Pass [Member] \| Dairy And Livestock And Agribusiness [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	247	207
2022	0	2,318
2021	2,074	1,515
2020	1,054	187
2019	120	69
Prior	205	628
Revolving loans amortized cost basis	280,524	400,229
Revolving loans converted to term loans	0	450
Total	284,224	405,603
Pass [Member] \| Municipal Lease Finance Receivables [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	6,442
2022	5,989	26,858
2021	26,088	6,814
2020	6,188	4,327
2019	4,266	4,948
Prior	32,867	31,292
Revolving loans amortized cost basis		0
Revolving loans converted to term loans		0
Total	75,398	80,681
Pass [Member] \| SFR mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	16,831	63,761
2022	61,882	46,748
2021	43,841	45,819
2020	44,529	33,585
2019	28,963	15,836
Prior	69,010	58,730
Revolving loans amortized cost basis		0
Revolving loans converted to term loans		0
Total	265,056	264,479
Pass [Member] \| Consumer Other [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	2,548	7,653
2022	4,763	3,722
2021	2,967	1,298
2020	830	926
2019	710	79
Prior	525	1,277
Revolving loans amortized cost basis	36,846	58,578
Revolving loans converted to term loans	900	1,107
Total	50,089	74,640
Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	11,887	7,240
2022	5,403	13,436
2021	17,851	12,686
2020	30,463	36,589
2019	49,449	28,398
Prior	84,740	78,625
Revolving loans amortized cost basis	69,684	33,783
Revolving loans converted to term loans	7,890	1,397
Total	277,367	212,154
Special Mention [Member] \| Commercial real estate loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	3,256	3,285
2022	4,417	12,114
2021	16,273	11,284
2020	28,896	32,976
2019	42,458	21,646
Prior	77,508	76,290
Revolving loans amortized cost basis	1,911	908
Revolving loans converted to term loans		0
Total	174,719	158,503
Special Mention [Member] \| Construction [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019		4,951
Prior	0	0
Revolving loans amortized cost basis		0
Revolving loans converted to term loans		0
Total		4,951
Special Mention [Member] \| SBA [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	0
2022		0
2021		0
2020		1,321
2019	1,890	1,293
Prior	2,560	2,065
Revolving loans amortized cost basis		0
Revolving loans converted to term loans		0
Total	4,450	4,679
Special Mention [Member] \| SBA - Paycheck Protection Program (PPP) [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	0
2022		0
2021		0
2020		0
2019		0
Prior	0	0
Revolving loans amortized cost basis		0
Revolving loans converted to term loans		0
Total		0
Special Mention [Member] \| Commercial And Industrial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	7,418	3,955
2022	986	761
2021	1,300	459
2020	643	1,693
2019	4,482	462
Prior	4,110	8
Revolving loans amortized cost basis	5,098	15,156
Revolving loans converted to term loans	5,702	544
Total	29,739	23,038
Special Mention [Member] \| Dairy And Livestock And Agribusiness [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	463	0
2022	0	0
2021	0	0
2020	0	599
2019	61	46
Prior	0	0
Revolving loans amortized cost basis	62,670	17,129
Revolving loans converted to term loans	1,304	853
Total	64,498	18,627
Special Mention [Member] \| Municipal Lease Finance Receivables [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	0
2022		0
2021		0
2020		0
2019		0
Prior	223	262
Revolving loans amortized cost basis		0
Revolving loans converted to term loans		0
Total	223	262
Special Mention [Member] \| SFR mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	750	0
2022		0
2021		943
2020	924	0
2019	558	0
Prior	339	0
Revolving loans amortized cost basis		0
Revolving loans converted to term loans		0
Total	2,571	943
Special Mention [Member] \| Consumer Other [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	0
2022		561
2021	278	0
2020		0
2019		0
Prior		0
Revolving loans amortized cost basis	5	590
Revolving loans converted to term loans	884	0
Total	1,167	1,151
Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	244	1,535
2022	8,441	0
2021		16,392
2020	22,598	17,256
2019	12,858	6,369
Prior	40,288	23,735
Revolving loans amortized cost basis	5,792	5,046
Revolving loans converted to term loans	2,025	8,325
Total	92,246	78,658
Substandard [Member] \| Commercial real estate loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	244	0
2022	8,168	0
2021	0	15,624
2020	22,598	16,297
2019	12,769	94
Prior	35,220	21,535
Revolving loans amortized cost basis	800	0
Revolving loans converted to term loans		0
Total	79,799	53,550
Substandard [Member] \| Construction [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019		0
Prior	0	0
Revolving loans amortized cost basis		0
Revolving loans converted to term loans		0
Total		0
Substandard [Member] \| SBA [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	0
2022		0
2021		0
2020		0
2019		556
Prior	3,340	1,181
Revolving loans amortized cost basis		0
Revolving loans converted to term loans		0
Total	3,340	1,737
Substandard [Member] \| SBA - Paycheck Protection Program (PPP) [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	0
2022		0
2021		0
2020		0
2019		0
Prior	0	0
Revolving loans amortized cost basis		0
Revolving loans converted to term loans		0
Total		0
Substandard [Member] \| Commercial And Industrial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	494
2022	273	0
2021		728
2020		959
2019	89	5,624
Prior	1,304	496
Revolving loans amortized cost basis	2,487	3,200
Revolving loans converted to term loans	1,050	761
Total	5,203	12,262
Substandard [Member] \| Dairy And Livestock And Agribusiness [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	1,041
2022	0	0
2021	0	40
2020	0	0
2019	0	95
Prior	208	113
Revolving loans amortized cost basis	2,498	1,841
Revolving loans converted to term loans	35	6,204
Total	2,741	9,334
Substandard [Member] \| Municipal Lease Finance Receivables [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	0
2022		0
2021		0
2020		0
2019		0
Prior		183
Revolving loans amortized cost basis		0
Revolving loans converted to term loans		0
Total		183
Substandard [Member] \| SFR mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	0
2022		0
2021		0
2020		0
2019		0
Prior	205	214
Revolving loans amortized cost basis		0
Revolving loans converted to term loans	339	388
Total	544	602
Substandard [Member] \| Consumer Other [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	0
2022		0
2021		0
2020		0
2019		0
Prior	11	13
Revolving loans amortized cost basis	7	5
Revolving loans converted to term loans	601	972
Total	619	990
Doubtful [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	0
2022		0
2021		0
2020		0
2019		0
Prior		0
Revolving loans amortized cost basis		0
Revolving loans converted to term loans		0
Total		0
Doubtful [Member] \| Commercial real estate loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019		0
Prior		0
Revolving loans amortized cost basis		0
Revolving loans converted to term loans		0
Total		0
Doubtful [Member] \| Construction [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	0
2022	0	0
2021	0	0
2020	0	0
2019		0
Prior	0	0
Revolving loans amortized cost basis		0
Revolving loans converted to term loans		0
Total	0	0
Doubtful [Member] \| SBA [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	0
2022		0
2021		0
2020		0
2019		0
Prior	0	0
Revolving loans amortized cost basis		0
Revolving loans converted to term loans		0
Total		0
Doubtful [Member] \| SBA - Paycheck Protection Program (PPP) [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2023	0	0
2022		0
2021		0
2020		0
2019		0
Prior	0	0

Loans and Lease Finance Receivables and Allowance for Credit Losses - Summary of loans by type and origination year, according to our internal risk ratings (Detail) - USD ($)
$ in Thousands