CREDIT QUALITY ASSESSMENT - Information about credit quality indicator by year of origination (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
2021	$ 961,411	$ 3,305,720
2020	2,937,967	1,774,275
2019	1,646,238	1,179,845
2018	1,091,611	1,016,641
2017	961,954	866,898
Prior	1,896,722	1,242,626
Revolving Loans	950,963	1,014,504
Total	10,446,866	10,400,509
Commercial investor real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2021	204,744	922,059
2020	882,937	767,459
2019	715,618	466,934
2018	469,104	470,150
2017	458,689	470,019
Prior	892,482	504,568
Revolving Loans	28,844	33,531
Total	3,652,418	3,634,720
Commercial investor real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2021	194,465	910,426
2020	881,973	763,214
2019	707,450	448,406
2018	452,909	448,698
2017	429,839	469,077
Prior	876,375	498,384
Revolving Loans	28,844	33,531
Total	3,571,855	3,571,736
Commercial investor real estate | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2021	10,000	11,044
2020	527	0
2019	1,993	4,879
2018	2,640	833
2017	701	269
Prior	2,646	27
Revolving Loans	0	0
Total	18,507	17,052
Commercial investor real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2021	279	589
2020	437	4,245
2019	6,175	13,649
2018	13,555	20,619
2017	28,149	673
Prior	13,461	6,157
Revolving Loans	0	0
Total	62,056	45,932
Commercial investor real estate | Doubtful
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	0	0
Total	0	0
Commercial owner-occupied real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2021	47,661	289,210
2020	290,210	389,393
2019	384,594	239,670
2018	228,156	197,841
2017	193,940	205,278
Prior	495,494	319,160
Revolving Loans	4,793	1,664
Total	1,644,848	1,642,216
Commercial owner-occupied real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2021	47,661	285,310
2020	287,070	385,058
2019	375,951	234,578
2018	222,539	192,634
2017	188,795	204,925
Prior	485,151	306,840
Revolving Loans	4,793	1,664
Total	1,611,960	1,611,009
Commercial owner-occupied real estate | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	2,290
2020	1,871	0
2019	4,327	3,027
2018	3,586	4,742
2017	4,698	134
Prior	5,279	4,079
Revolving Loans	0	0
Total	19,761	14,272
Commercial owner-occupied real estate | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	1,610
2020	1,269	4,335
2019	4,316	2,065
2018	2,031	465
2017	447	219
Prior	5,064	8,009
Revolving Loans	0	0
Total	13,127	16,703
Commercial owner-occupied real estate | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	0	0
Prior	0	232
Revolving Loans	0	0
Total	0	232
Commercial AD&C
Financing Receivable, Credit Quality Indicator [Line Items]
2021	175,861	488,781
2020	374,686	262,428
2019	245,642	149,703
2018	110,557	64,008
2017	60,779	2,932
Prior	2,843	2,357
Revolving Loans	80,645	80,764
Total	1,051,013	1,050,973
Commercial AD&C | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2021	174,120	485,631
2020	373,158	261,537
2019	244,751	149,703
2018	110,557	50,192
2017	47,150	89
Prior	0	2,357
Revolving Loans	80,645	80,764
Total	1,030,381	1,030,273
Commercial AD&C | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2021	639	1,711
2020	1,073	0
2019	0	0
2018	0	0
2017	0	0
Prior	0	0
Revolving Loans	0	0
Total	1,712	1,711
Commercial AD&C | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2021	1,102	1,439
2020	455	891
2019	891	0
2018	0	13,816
2017	13,629	2,843
Prior	2,843	0
Revolving Loans	0	0
Total	18,920	18,989
Commercial AD&C | Doubtful
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	0	0
Total	0	0
Residential mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
2021	44,604	236,909
2020	218,269	85,106
2019	78,965	158,382
2018	130,593	188,970
2017	165,064	143,557
Prior	385,051	292,255
Revolving Loans	0	0
Total	1,022,546	1,105,179
Residential mortgage | 660-850
Financing Receivable, Credit Quality Indicator [Line Items]
2021	43,362	229,033
2020	209,544	74,054
2019	66,700	138,824
2018	113,850	172,493
2017	153,972	129,701
Prior	336,256	251,065
Revolving Loans	0	0
Total	923,684	995,170
Residential mortgage | 600-659
Financing Receivable, Credit Quality Indicator [Line Items]
2021	745	4,824
2020	4,962	7,706
2019	9,539	10,763
2018	8,498	11,719
2017	8,044	8,173
Prior	25,851	21,424
Revolving Loans	0	0
Total	57,639	64,609
Residential mortgage | 540-599
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	350
2020	1,445	1,238
2019	1,181	5,219
2018	5,063	2,608
2017	1,930	4,791
Prior	14,187	10,167
Revolving Loans	0	0
Total	23,806	24,373
Residential mortgage | less than 540
Financing Receivable, Credit Quality Indicator [Line Items]
2021	497	2,702
2020	2,318	2,108
2019	1,545	3,576
2018	3,182	2,150
2017	1,118	892
Prior	8,757	9,599
Revolving Loans	0	0
Total	17,417	21,027
Residential construction
Financing Receivable, Credit Quality Indicator [Line Items]
2021	27,097	115,201
2020	102,244	47,836
2019	23,802	14,543
2018	14,166	2,805
2017	1,248	2,062
Prior	2,107	0
Revolving Loans	364	172
Total	171,028	182,619
Residential construction | 660-850
Financing Receivable, Credit Quality Indicator [Line Items]
2021	27,097	112,604
2020	101,290	44,647
2019	21,059	14,543
2018	14,166	2,805
2017	1,248	1,693
Prior	1,738	0
Revolving Loans	364	172
Total	166,962	176,464
Residential construction | 600-659
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	1,743
2020	0	3,189
2019	2,743	0
2018	0	0
2017	0	0
Prior	369	0
Revolving Loans	0	0
Total	3,112	4,932
Residential construction | 540-599
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	0
2020	0	0
2019	0	0
2018	0	0
2017	0	369
Prior	0	0
Revolving Loans	0	0
Total	0	369
Residential construction | less than 540
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	854
2020	954	0
2019	0	0
2018	0	0
2017	0	0
Prior	0	0
Revolving Loans	0	0
Total	954	854
Commercial Business
Financing Receivable, Credit Quality Indicator [Line Items]
Total	8,759,388	8,595,457
Commercial Business | Commercial business
Financing Receivable, Credit Quality Indicator [Line Items]
2021	460,040	1,249,771
2020	1,066,322	215,623
2019	191,501	144,348
2018	133,497	89,205
2017	79,373	38,836
Prior	78,545	87,689
Revolving Loans	401,831	442,076
Total	2,411,109	2,267,548
Commercial Business | Commercial business | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2021	459,815	1,244,822
2020	1,059,494	208,682
2019	179,214	138,861
2018	129,096	86,830
2017	77,302	34,498
Prior	71,681	81,760
Revolving Loans	396,258	433,016
Total	2,372,860	2,228,469
Commercial Business | Commercial business | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	1,929
2020	2,043	1,382
2019	8,793	1,119
2018	1,063	708
2017	1,214	309
Prior	845	621
Revolving Loans	3,792	4,319
Total	17,750	10,387
Commercial Business | Commercial business | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2021	225	2,914
2020	4,785	4,564
2019	3,494	3,519
2018	3,338	1,631
2017	857	2,745
Prior	6,019	3,456
Revolving Loans	1,781	1,829
Total	20,499	20,658
Commercial Business | Commercial business | Doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	106
2020	0	995
2019	0	849
2018	0	36
2017	0	1,284
Prior	0	1,852
Revolving Loans	0	2,912
Total	0	8,034
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
2021	1,404	3,789
2020	3,299	6,430
2019	6,116	6,265
2018	5,538	3,662
2017	2,861	4,214
Prior	40,200	36,597
Revolving Loans	434,486	456,297
Total	493,904	517,254
Consumer | 660-850
Financing Receivable, Credit Quality Indicator [Line Items]
2021	1,054	2,575
2020	2,200	4,609
2019	4,263	5,112
2018	4,213	2,110
2017	1,567	2,614
Prior	27,406	24,444
Revolving Loans	400,050	417,737
Total	440,753	459,201
Consumer | 600-659
Financing Receivable, Credit Quality Indicator [Line Items]
2021	247	374
2020	265	445
2019	1,138	334
2018	484	428
2017	259	467
Prior	6,092	5,401
Revolving Loans	17,590	21,052
Total	26,075	28,501
Consumer | 540-599
Financing Receivable, Credit Quality Indicator [Line Items]
2021	0	89
2020	105	1,216
2019	564	294
2018	272	339
2017	270	601
Prior	3,425	3,926
Revolving Loans	6,938	6,153
Total	11,574	12,618
Consumer | less than 540
Financing Receivable, Credit Quality Indicator [Line Items]
2021	103	751
2020	729	160
2019	151	525
2018	569	785
2017	765	532
Prior	3,277	2,826
Revolving Loans	9,908	11,355
Total	$ 15,502	$ 16,934