INVESTMENTS - Gross Unrealized Losses and Fair Value by Length of Time in Unrealized Loss Position (Detail) $ in Thousands	Jun. 30, 2024 USD ($) security	Dec. 31, 2023 USD ($) security
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	473	454
Fair Value
Less Than 12 Months	$ 102,316	$ 26,893
12 Months or More	972,531	1,050,289
Total	1,074,847	1,077,182
Unrealized Losses
Less Than 12 Months	569	190
12 Months or More	124,636	118,130
Total	$ 125,205	$ 118,320
U.S. treasuries and government agencies
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	8	10
Fair Value
Less Than 12 Months	$ 0	$ 0
12 Months or More	82,959	96,927
Total	82,959	96,927
Unrealized Losses
Less Than 12 Months	0	0
12 Months or More	4,093	4,751
Total	$ 4,093	$ 4,751
State and municipal
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	123	123
Fair Value
Less Than 12 Months	$ 3,935	$ 4,162
12 Months or More	254,490	262,081
Total	258,425	266,243
Unrealized Losses
Less Than 12 Months	17	84
12 Months or More	48,162	43,208
Total	$ 48,179	$ 43,292
Mortgage-backed and asset-backed
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	342	321
Fair Value
Less Than 12 Months	$ 98,381	$ 22,731
12 Months or More	635,082	691,281
Total	733,463	714,012
Unrealized Losses
Less Than 12 Months	552	106
12 Months or More	72,381	70,171
Total	$ 72,933	$ 70,277