INVESTMENTS - Gross Unrealized Losses and Fair Value by Length of Time in Unrealized Loss Position (Detail) $ in Thousands	Sep. 30, 2022 USD ($) security	Dec. 31, 2021 USD ($) security
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	498	141
Fair Value
Less Than 12 Months	$ 946,523	$ 778,714
12 Months or More	271,922	59,597
Total	1,218,445	838,311
Unrealized Losses
Less Than 12 Months	111,976	12,583
12 Months or More	55,131	2,837
Total	$ 167,107	$ 15,420
U.S. treasuries and government agencies
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	10	5
Fair Value
Less Than 12 Months	$ 88,079	$ 49,695
12 Months or More	4,724	0
Total	92,803	49,695
Unrealized Losses
Less Than 12 Months	7,672	150
12 Months or More	263	0
Total	$ 7,935	$ 150
State and municipal
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	160	32
Fair Value
Less Than 12 Months	$ 222,651	$ 63,206
12 Months or More	52,441	21,740
Total	275,092	84,946
Unrealized Losses
Less Than 12 Months	42,761	2,288
12 Months or More	22,797	1,157
Total	$ 65,558	$ 3,445
Mortgage-backed and asset-backed
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	328	104
Fair Value
Less Than 12 Months	$ 635,793	$ 665,813
12 Months or More	214,757	37,857
Total	850,550	703,670
Unrealized Losses
Less Than 12 Months	61,543	10,145
12 Months or More	32,071	1,680
Total	$ 93,614	$ 11,825