INVESTMENTS - Gross Unrealized Losses and Fair Value by Length of Time in Unrealized Loss Position (Detail) $ in Thousands	Mar. 31, 2022 USD ($) security	Dec. 31, 2021 USD ($) security
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	367	141
Fair Value
Less Than 12 Months	$ 1,098,643	$ 778,714
12 Months or More	50,651	59,597
Total	1,149,294	838,311
Unrealized Losses
Less Than 12 Months	58,040	12,583
12 Months or More	8,949	2,837
Total	$ 66,989	$ 15,420
U.S. treasuries and government agencies
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	9	5
Fair Value
Less Than 12 Months	$ 89,548	$ 49,695
12 Months or More	0	0
Total	89,548	49,695
Unrealized Losses
Less Than 12 Months	3,892	150
12 Months or More	0	0
Total	$ 3,892	$ 150
State and municipal
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	114	32
Fair Value
Less Than 12 Months	$ 225,812	$ 63,206
12 Months or More	36,982	21,740
Total	262,794	84,946
Unrealized Losses
Less Than 12 Months	18,281	2,288
12 Months or More	8,017	1,157
Total	$ 26,298	$ 3,445
Mortgage-backed and asset-backed
Debt Securities, Available-for-sale [Line Items]
Number of Securities | security	244	104
Fair Value
Less Than 12 Months	$ 783,283	$ 665,813
12 Months or More	13,669	37,857
Total	796,952	703,670
Unrealized Losses
Less Than 12 Months	35,867	10,145
12 Months or More	932	1,680
Total	$ 36,799	$ 11,825