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	Jun. 30, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
2021	$ 1,119,794	$ 2,129,465
2020	1,477,398	954,344
2019	871,606	804,015
2018	740,397	840,334
2017	721,326	666,584
Prior	2,286,731	1,975,259
Revolving loans amortized cost basis	774,142	924,822
Revolving loans converted to term loans	79,916	53,985
Total	8,071,310	8,348,808
Commercial real estate loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	603,433	988,831
2020	992,761	698,744
2019	652,848	639,959
2018	598,103	668,892
2017	589,597	570,031
Prior	1,995,801	1,710,506
Revolving loans amortized cost basis	184,568	198,663
Revolving loans converted to term loans	53,585	25,883
Total	5,670,696	5,501,509
Construction [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	3,707	14,511
2020	17,859	9,350
2019	6,993	14,945
2018	10,831	2,258
2017	0	0
Prior	0	4
Revolving loans amortized cost basis	48,890	44,077
Revolving loans converted to term loans	0	0
Total	88,280	85,145
SBA [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	34,423	47,901
2020	42,665	12,821
2019	11,315	45,854
2018	43,160	69,788
2017	55,863	29,026
Prior	104,352	95,530
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	2,976
Total	291,778	303,896
SBA - Paycheck Protection Program (PPP) [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	395,349	882,986
2020	262,466	0
2019	0	0
2018	0	0
2017	0	0
Prior	0	0
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	0
Total	657,815	882,986
Commercial And Industrial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	53,700	110,819
2020	96,391	169,991
2019	149,557	68,341
2018	62,764	59,353
2017	45,404	32,529
Prior	88,605	80,995
Revolving loans amortized cost basis	244,659	281,322
Revolving loans converted to term loans	8,037	8,712
Total	749,117	812,062
Dairy And Livestock And Agribusiness [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	1,919
2020	1,014	1,765
2019	1,527	2,347
2018	1,453	6,373
2017	225	2,405
Prior	1,206	320
Revolving loans amortized cost basis	237,344	332,466
Revolving loans converted to term loans	15,012	13,551
Total	257,781	361,146
Municipal Lease Finance Receivables [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	5,262	8,478
2020	8,122	0
2019	0	2,556
2018	279	10,249
2017	10,061	3,586
Prior	20,933	20,678
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	0
Total	44,657	45,547
SFR mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	19,740	65,463
2020	53,029	59,596
2019	47,707	29,142
2018	23,121	22,452
2017	19,398	27,421
Prior	73,557	66,002
Revolving loans amortized cost basis	152	3
Revolving loans converted to term loans	420	432
Total	237,124	270,511
Consumer Other [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	4,180	8,557
2020	3,091	2,077
2019	1,659	871
2018	686	969
2017	778	1,586
Prior	2,277	1,224
Revolving loans amortized cost basis	58,529	68,291
Revolving loans converted to term loans	2,862	2,431
Total	74,062	86,006
Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	1,102,908	2,112,914
2020	1,463,516	944,750
2019	860,111	763,869
2018	697,928	774,130
2017	657,398	640,874
Prior	2,196,475	1,893,124
Revolving loans amortized cost basis	745,869	880,898
Revolving loans converted to term loans	46,329	35,633
Total	7,770,534	8,046,192
Pass [Member] \| Commercial real estate loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	590,633	979,499
2020	983,583	691,091
2019	643,212	607,753
2018	569,056	617,640
2017	536,282	550,105
Prior	1,918,411	1,646,876
Revolving loans amortized cost basis	179,984	192,583
Revolving loans converted to term loans	36,916	24,548
Total	5,458,077	5,310,095
Pass [Member] \| Construction [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	3,707	14,511
2020	17,859	9,350
2019	6,993	14,945
2018	3,038	2,258
2017	0	0
Prior	0	4
Revolving loans amortized cost basis	47,207	44,077
Revolving loans converted to term loans	0	0
Total	78,804	85,145
Pass [Member] \| SBA [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	34,423	47,901
2020	42,665	12,821
2019	11,315	44,950
2018	42,296	58,839
2017	47,190	26,136
Prior	95,505	86,085
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	2,976
Total	273,394	279,708
Pass [Member] \| SBA - Paycheck Protection Program (PPP) [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	395,349	882,986
2020	260,963	0
2019	0	0
2018	0	0
2017	0	0
Prior	0	0
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	0
Total	656,312	882,986
Pass [Member] \| Commercial And Industrial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	50,590	104,478
2020	93,190	168,050
2019	147,698	62,453
2018	58,447	56,043
2017	43,464	32,149
Prior	87,688	76,019
Revolving loans amortized cost basis	234,803	257,250
Revolving loans converted to term loans	6,423	6,058
Total	722,303	762,500
Pass [Member] \| Dairy And Livestock And Agribusiness [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	1,041
2020	1,014	1,765
2019	1,527	1,199
2018	1,005	5,680
2017	225	120
Prior	349	320
Revolving loans amortized cost basis	226,192	319,211
Revolving loans converted to term loans	587	363
Total	230,899	329,699
Pass [Member] \| Municipal Lease Finance Receivables [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	5,262	8,478
2020	8,122	0
2019	0	2,556
2018	279	10,249
2017	10,061	3,586
Prior	20,557	20,266
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	0
Total	44,281	45,135
Pass [Member] \| SFR mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	19,740	65,463
2020	53,029	59,596
2019	47,707	29,142
2018	23,121	22,452
2017	19,398	27,192
Prior	71,945	62,593
Revolving loans amortized cost basis	152	3
Revolving loans converted to term loans	0	0
Total	235,092	266,441
Pass [Member] \| Consumer Other [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	3,204	8,557
2020	3,091	2,077
2019	1,659	871
2018	686	969
2017	778	1,586
Prior	2,020	961
Revolving loans amortized cost basis	57,531	67,774
Revolving loans converted to term loans	2,403	1,688
Total	71,372	84,483
Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	11,793	12,205
2020	10,881	8,243
2019	10,891	32,305
2018	39,324	50,344
2017	53,079	18,829
Prior	75,511	61,325
Revolving loans amortized cost basis	25,363	36,887
Revolving loans converted to term loans	24,890	3,659
Total	251,732	223,797
Special Mention [Member] \| Commercial real estate loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	10,350	9,332
2020	9,178	7,162
2019	9,165	30,049
2018	29,047	43,870
2017	48,258	17,398
Prior	67,790	49,840
Revolving loans amortized cost basis	4,584	5,720
Revolving loans converted to term loans	16,348	994
Total	194,720	164,365
Special Mention [Member] \| Construction [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	7,793	0
2017	0	0
Prior	0	0
Revolving loans amortized cost basis	1,683	0
Revolving loans converted to term loans	0	0
Total	9,476	0
Special Mention [Member] \| SBA [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	5,446
2017	4,186	1,336
Prior	5,988	5,648
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	0
Total	10,174	12,430
Special Mention [Member] \| SBA - Paycheck Protection Program (PPP) [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	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]
2021	467	1,995
2020	1,703	1,081
2019	1,726	1,892
2018	2,154	1,028
2017	635	95
Prior	220	4,882
Revolving loans amortized cost basis	6,951	17,395
Revolving loans converted to term loans	221	1,132
Total	14,077	29,500
Special Mention [Member] \| Dairy And Livestock And Agribusiness [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	878
2020	0	0
2019	0	364
2018	330	0
2017	0	0
Prior	857	0
Revolving loans amortized cost basis	11,152	13,255
Revolving loans converted to term loans	8,321	1,511
Total	20,660	16,008
Special Mention [Member] \| Municipal Lease Finance Receivables [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	0	0
Prior	376	412
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	0
Total	376	412
Special Mention [Member] \| SFR mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	0	0
Prior	192	452
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	0
Total	192	452
Special Mention [Member] \| Consumer Other [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	976	0
2020	0	0
2019	0	0
2018	0	0
2017	0	0
Prior	88	91
Revolving loans amortized cost basis	993	517
Revolving loans converted to term loans	0	22
Total	2,057	630
Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	5,093	4,346
2020	3,001	1,351
2019	604	7,841
2018	3,145	15,860
2017	10,849	6,881
Prior	14,745	20,810
Revolving loans amortized cost basis	2,910	7,037
Revolving loans converted to term loans	8,697	14,693
Total	49,044	78,819
Substandard [Member] \| Commercial real estate loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	2,450	0
2020	0	491
2019	471	2,157
2018	0	7,382
2017	5,057	2,528
Prior	9,600	13,790
Revolving loans amortized cost basis	0	360
Revolving loans converted to term loans	321	341
Total	17,899	27,049
Substandard [Member] \| Construction [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	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] \| SBA [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	0
2020	0	0
2019	0	904
2018	864	5,503
2017	4,487	1,554
Prior	2,859	3,797
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	0
Total	8,210	11,758
Substandard [Member] \| SBA - Paycheck Protection Program (PPP) [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	0
2020	1,503	0
2019	0	0
2018	0	0
2017	0	0
Prior	0	0
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	0	0
Total	1,503	0
Substandard [Member] \| Commercial And Industrial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	2,643	4,346
2020	1,498	860
2019	133	3,996
2018	2,163	2,282
2017	1,305	285
Prior	697	94
Revolving loans amortized cost basis	2,905	6,677
Revolving loans converted to term loans	1,393	1,522
Total	12,737	20,062
Substandard [Member] \| Dairy And Livestock And Agribusiness [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	0
2020	0	0
2019	0	784
2018	118	693
2017	0	2,285
Prior	0	0
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	6,104	11,677
Total	6,222	15,439
Substandard [Member] \| Municipal Lease Finance Receivables [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	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] \| SFR mortgage [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	0	229
Prior	1,420	2,957
Revolving loans amortized cost basis	0	0
Revolving loans converted to term loans	420	432
Total	1,840	3,618
Substandard [Member] \| Consumer Other [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	0	0
Prior	169	172
Revolving loans amortized cost basis	5	0
Revolving loans converted to term loans	459	721
Total	633	893
Doubtful [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	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]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	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]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	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]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	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 - Paycheck Protection Program (PPP) [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	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 And Industrial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	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