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	12 Months Ended
Sep. 30, 2024	Dec. 31, 2023
Financing Receivable, Credit Quality Indicator [Line Items]
2024	$ 363,232	$ 651,552
2023	604,143	1,608,241
2022	1,539,662	1,402,964
2021	1,308,597	1,124,447
2020	1,030,474	668,632
Prior	2,783,099	2,453,629
Revolving loans amortized cost basis	886,302	943,285
Revolving loans converted to term loans	57,056	52,160
Total	8,572,565	8,904,910
Financing Receivable Accrued Interest Year Three Originated Two Years Before Current Fiscal Year Writeoff	300
Financing Receivable Accrued Interest Originated More than Five Years before Current Fiscal Year Writeoff	3,609
Gross Charge Offs Revolving Loans Amortized Term Loans	1
Gross charge-offs Revolving loans converted to term loans	434	113
Gross charge-off prior		292
Gross charge-off total	4,344	405
Commercial real estate loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	235,472	451,976
2023	432,368	1,327,587
2022	1,295,115	1,152,090
2021	1,112,187	938,359
2020	880,908	554,351
Prior	2,432,661	2,146,639
Revolving loans amortized cost basis	192,020	174,935
Revolving loans converted to term loans	37,906	38,568
Total	6,618,637	6,784,505
Financing Receivable Accrued Interest Originated More than Five Years before Current Fiscal Year Writeoff	2,258
Gross charge-off total	2,258
Construction [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	2,977	1,274
2023	1,986	15,046
2022	7,730	24,418
2021	2,062	8,058
2020	0	0
Prior	0	0
Revolving loans amortized cost basis	0	17,938
Revolving loans converted to term loans	0	0
Total	14,755	66,734
SBA [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	25,973	20,701
2023	17,213	49,839
2022	48,734	51,038
2021	49,661	34,090
2020	28,741	8,117
Prior	101,679	106,834
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	0
Total	272,001	270,619
Financing Receivable Accrued Interest Originated More than Five Years before Current Fiscal Year Writeoff	165	288
Gross charge-off total	165	288
SBA - Paycheck Protection Program (PPP) [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	699
2021	366	2,037
2020	889	0
Prior	0	0
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	0
Total	1,255	2,736
Commercial And Industrial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	77,701	148,909
2023	128,081	144,842
2022	120,498	100,804
2021	74,600	89,295
2020	73,048	72,555
Prior	128,957	99,309
Revolving loans amortized cost basis	319,325	302,555
Revolving loans converted to term loans	14,279	11,626
Total	936,489	969,895
Financing Receivable Accrued Interest Year Three Originated Two Years Before Current Fiscal Year Writeoff	300
Financing Receivable Accrued Interest Originated More than Five Years before Current Fiscal Year Writeoff	1,186
Gross charge-offs Revolving loans converted to term loans	431	109
Gross charge-off total	1,917	109
Dairy And Livestock And Agribusiness [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	427	744
2023	0	0
2022	0	1,586
2021	642	931
2020	889	105
Prior	270	268
Revolving loans amortized cost basis	337,752	409,257
Revolving loans converted to term loans	2,465	0
Total	342,445	412,891
Municipal Lease Finance Receivables [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	1,711	0
2023	0	5,735
2022	5,345	25,803
2021	25,008	5,981
2020	5,354	4,267
Prior	30,167	31,804
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	0
Total	67,585	73,590
SFR mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	14,861	23,037
2023	21,171	61,070
2022	60,051	43,573
2021	41,849	44,994
2020	40,286	28,593
Prior	88,669	68,277
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	294	324
Total	267,181	269,868
Consumer and Other [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	4,110	4,911
2023	3,324	4,122
2022	2,189	2,953
2021	2,222	702
2020	359	644
Prior	696	498
Revolving loans amortized cost basis	37,205	38,600
Revolving loans converted to term loans	2,112	1,642
Total	52,217	54,072
Financing Receivable Accrued Interest Originated More than Five Years before Current Fiscal Year Writeoff		4
Gross Charge Offs Revolving Loans Amortized Term Loans	1
Gross charge-offs Revolving loans converted to term loans	3	4
Gross charge-off total	4	8
Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	361,887	638,501
2023	594,512	1,593,595
2022	1,504,134	1,381,084
2021	1,272,459	1,065,424
2020	982,061	605,169
Prior	2,609,074	2,337,278
Revolving loans amortized cost basis	819,284	854,820
Revolving loans converted to term loans	43,556	44,899
Total	8,186,967	8,520,770
Pass [Member] \| Commercial real estate loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	234,801	447,991
2023	427,623	1,315,563
2022	1,262,430	1,133,331
2021	1,080,704	885,590
2020	838,577	497,541
Prior	2,270,791	2,041,329
Revolving loans amortized cost basis	187,981	171,223
Revolving loans converted to term loans	36,610	38,568
Total	6,339,517	6,531,136
Pass [Member] \| Construction [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	2,977	1,274
2023	1,986	15,046
2022	7,730	22,288
2021	0	8,058
2020	0	0
Prior	0	0
Revolving loans amortized cost basis	0	17,938
Revolving loans converted to term loans	0	0
Total	12,693	64,604
Pass [Member] \| SBA [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	25,973	20,701
2023	17,213	48,212
2022	47,143	51,038
2021	49,661	29,306
2020	24,005	6,236
Prior	95,298	101,856
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	0
Total	259,293	257,349
Pass [Member] \| SBA - Paycheck Protection Program (PPP) [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	699
2021	366	2,037
2020	889	0
Prior	0	0
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	0
Total	1,255	2,736
Pass [Member] \| Commercial And Industrial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	77,027	141,080
2023	123,195	143,847
2022	119,246	100,059
2021	72,164	88,743
2020	72,604	68,352
Prior	124,580	94,027
Revolving loans amortized cost basis	307,261	289,539
Revolving loans converted to term loans	5,131	5,460
Total	901,208	931,107
Pass [Member] \| Dairy And Livestock And Agribusiness [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	427	296
2023	0	0
2022	0	1,586
2021	642	931
2020	889	80
Prior	210	208
Revolving loans amortized cost basis	286,841	337,525
Revolving loans converted to term loans	0	0
Total	289,009	340,626
Pass [Member] \| Municipal Lease Finance Receivables [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	1,711	0
2023	0	5,735
2022	5,345	25,803
2021	25,008	5,981
2020	5,354	4,267
Prior	30,026	31,622
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	0
Total	67,444	73,408
Pass [Member] \| SFR mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	14,861	22,248
2023	21,171	61,070
2022	60,051	43,573
2021	41,849	44,076
2020	39,384	28,049
Prior	87,473	67,750
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	0
Total	264,789	266,766
Pass [Member] \| Consumer and Other [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	4,110	4,911
2023	3,324	4,122
2022	2,189	2,707
2021	2,065	702
2020	359	644
Prior	696	486
Revolving loans amortized cost basis	37,201	38,595
Revolving loans converted to term loans	1,815	871
Total	51,759	53,038
Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	1,345	12,307
2023	7,915	6,262
2022	24,794	18,989
2021	27,773	25,622
2020	23,104	49,639
Prior	114,798	80,928
Revolving loans amortized cost basis	54,092	82,676
Revolving loans converted to term loans	7,171	5,520
Total	260,992	281,943
Special Mention [Member] \| Commercial real estate loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	671	3,241
2023	4,501	3,897
2022	23,795	15,868
2021	25,259	19,368
2020	17,022	43,824
Prior	106,569	74,673
Revolving loans amortized cost basis	3,075	2,911
Revolving loans converted to term loans	1,296	0
Total	182,188	163,782
Special Mention [Member] \| Construction [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	2,130
2021	0	0
2020	0	0
Prior	0	0
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	0
Total	0	2,130
Special Mention [Member] \| SBA [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	1,627
2022	0	0
2021	0	4,784
2020	4,736	1,132
Prior	2,895	1,760
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	0
Total	7,631	9,303
Special Mention [Member] \| SBA - Paycheck Protection Program (PPP) [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior	0	0
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	0
Total	0	0
Special Mention [Member] \| Commercial And Industrial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	674	7,829
2023	3,414	738
2022	999	745
2021	2,357	552
2020	444	4,114
Prior	4,370	3,986
Revolving loans amortized cost basis	9,664	10,529
Revolving loans converted to term loans	5,173	5,347
Total	27,095	33,840
Special Mention [Member] \| Dairy And Livestock And Agribusiness [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	448
2023	0	0
2022	0	0
2021	0	0
2020	0	25
Prior	0	0
Revolving loans amortized cost basis	41,349	69,232
Revolving loans converted to term loans	408	0
Total	41,757	69,705
Special Mention [Member] \| Municipal Lease Finance Receivables [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior	141	182
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	0
Total	141	182
Special Mention [Member] \| SFR mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	789
2023	0	0
2022	0	0
2021	0	918
2020	902	544
Prior	823	327
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	294	0
Total	2,019	2,578
Special Mention [Member] \| Consumer and Other [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	246
2021	157	0
2020	0	0
Prior	0	0
Revolving loans amortized cost basis	4	4
Revolving loans converted to term loans	0	173
Total	161	423
Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	744
2023	1,716	8,384
2022	10,734	2,891
2021	8,365	33,401
2020	25,309	13,824
Prior	59,227	35,423
Revolving loans amortized cost basis	12,926	5,789
Revolving loans converted to term loans	6,329	1,741
Total	124,606	102,197
Substandard [Member] \| Commercial real estate loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	744
2023	244	8,127
2022	8,890	2,891
2021	6,224	33,401
2020	25,309	12,986
Prior	55,301	30,637
Revolving loans amortized cost basis	964	801
Revolving loans converted to term loans		0
Total	96,932	89,587
Substandard [Member] \| Construction [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024		0
2023		0
2022	0	0
2021	2,062	0
2020	0	0
Prior	0	0
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	0
Total	2,062	0
Substandard [Member] \| SBA [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024		0
2023		0
2022	1,591	0
2021		0
2020		749
Prior	3,486	3,218
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	0
Total	5,077	3,967
Substandard [Member] \| SBA - Paycheck Protection Program (PPP) [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior	0	0
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	0
Total	0	0
Substandard [Member] \| Commercial And Industrial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	1,472	257
2022	253	0
2021	79	0
2020	0	89
Prior	7	1,296
Revolving loans amortized cost basis	2,400	2,487
Revolving loans converted to term loans	3,975	819
Total	8,186	4,948
Substandard [Member] \| Dairy And Livestock And Agribusiness [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0
2021	0
2020	0
Prior	60	60
Revolving loans amortized cost basis	9,562	2,500
Revolving loans converted to term loans	2,057	0
Total	11,679	2,560
Substandard [Member] \| Municipal Lease Finance Receivables [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term loans	0
Total	0
Substandard [Member] \| SFR mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior	373	200
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	324
Total	373	524
Substandard [Member] \| Consumer and Other [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior	0	12
Revolving loans amortized cost basis	0	1
Revolving loans converted to term loans	297	598
Total	297	611
Doubtful [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior	0	0
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	0
Total	0	0
Doubtful [Member] \| Commercial real estate loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior	0	0
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	0
Total	0	0
Doubtful [Member] \| Construction [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior	0	0
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	0
Total	0	0
Doubtful [Member] \| SBA [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2024	0	0
2023	0	0
2022	0	0
2021	0	0
2020	0	0
Prior	0	0
Revolving loans amortized cost basis	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