INVESTMENTS - Gross Unrealized Losses and Fair Value by Length of Time in Unrealized Loss Position (Detail) $ in Thousands	Jun. 30, 2023 USD ($) security	Dec. 31, 2022 USD ($) security
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	464	464
Fair Value
Less Than 12 Months	$ 175,640	$ 779,965
12 Months or More	957,056	400,181
Total	1,132,696	1,180,146
Unrealized Losses
Less Than 12 Months	6,530	79,408
12 Months or More	138,641	72,974
Total	$ 145,171	$ 152,382
U.S. treasuries and government agencies
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	10	10
Fair Value
Less Than 12 Months	$ 0	$ 53,139
12 Months or More	94,345	40,483
Total	94,345	93,622
Unrealized Losses
Less Than 12 Months	0	3,653
12 Months or More	6,954	3,651
Total	$ 6,954	$ 7,304
State and municipal
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	127	130
Fair Value
Less Than 12 Months	$ 17,222	$ 200,439
12 Months or More	249,495	62,482
Total	266,717	262,921
Unrealized Losses
Less Than 12 Months	488	30,803
12 Months or More	50,077	25,723
Total	$ 50,565	$ 56,526
Mortgage-backed and asset-backed
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	327	324
Fair Value
Less Than 12 Months	$ 158,418	$ 526,387
12 Months or More	613,216	297,216
Total	771,634	823,603
Unrealized Losses
Less Than 12 Months	6,042	44,952
12 Months or More	81,610	43,600
Total	$ 87,652	$ 88,552