INVESTMENTS - Estimated fair values of debt securities by contractual maturity (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Fair Value
Total available-for-sale debt securities	$ 1,259,945	$ 1,465,896
Amortized Cost
Total available-for-sale debt securities	1,326,330	1,466,350
Fair Value
Total held-to-maturity debt securities	275,834	0
Amortized Cost
Total held-to-maturity debt securities	285,339	0
U.S. treasuries and government agencies
Fair Value
One year or less	8,991	12,029
One to five years	96,507	56,510
Five to ten years	0	0
After ten years	0	0
Total available-for-sale debt securities	105,498	68,539
Amortized Cost
One year or less	8,997	11,995
One to five years	100,367	56,492
Five to ten years	0	0
After ten years	0	0
Total available-for-sale debt securities	109,364	68,487
State and municipal
Fair Value
One year or less	12,421	12,821
One to five years	53,025	27,408
Five to ten years	39,651	42,960
After ten years	216,756	243,213
Total available-for-sale debt securities	321,853	326,402
Amortized Cost
One year or less	12,358	12,709
One to five years	53,539	26,637
Five to ten years	41,698	42,661
After ten years	240,282	241,279
Total available-for-sale debt securities	347,877	323,286
Mortgage-backed and asset-backed
Fair Value
One year or less	10,263	9,272
One to five years	8,095	14,752
Five to ten years	336,206	388,918
After ten years	478,030	658,013
Total available-for-sale debt securities	832,594	1,070,955
Amortized Cost
One year or less	10,283	9,239
One to five years	8,212	14,575
Five to ten years	351,404	390,569
After ten years	499,190	660,194
Total available-for-sale debt securities	869,089	1,074,577
Fair Value
One year or less	0	0
One to five years	0	0
Five to ten years	42,043	0
After ten years	233,791	0
Total held-to-maturity debt securities	275,834	0
Amortized Cost
One year or less	0	0
One to five years	0	0
Five to ten years	43,004	0
After ten years	242,335	0
Total held-to-maturity debt securities	$ 285,339	$ 0