MERCHANDISE TRUSTS - Cost and Market Value Associated with Assets Held in Merchandise Trusts (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
West Virginia Trust Receivable
Schedule Of Available For Sale Securities [Line Items]
Fair Value	$ 10,300	$ 10,000
Variable Interest Entity, Primary Beneficiary | Merchandise Trusts
Schedule Of Available For Sale Securities [Line Items]
Cost	544,263	486,161
Gross Unrealized Gains	30,054	40,661
Gross Unrealized Losses	(6,464)	(10,538)
Fair Value	567,853	516,284
Fair Value, Assets held for sale		14,831
Cost, Excluding assets held for sale		486,161
Gross Unrealized Gains, Excluding assets held for sale		40,661
Gross Unrealized Losses, Excluding assets held for sale		(10,538)
Fair Value, Excluding assets held for sale		501,453
Variable Interest Entity, Primary Beneficiary | Short-term investments | Merchandise Trusts | Level 1
Schedule Of Available For Sale Securities [Line Items]
Cost	51,243	41,039
Gross Unrealized Gains		12
Fair Value	51,243	41,051
Variable Interest Entity, Primary Beneficiary | Fixed maturities | Merchandise Trusts
Schedule Of Available For Sale Securities [Line Items]
Cost	1	25,984
Gross Unrealized Gains	1	2,216
Gross Unrealized Losses		(1,332)
Fair Value	2	26,868
Variable Interest Entity, Primary Beneficiary | Fixed maturities | Merchandise Trusts | U.S. governmental securities | Level 2
Schedule Of Available For Sale Securities [Line Items]
Cost	1	1
Fair Value	1	1
Variable Interest Entity, Primary Beneficiary | Fixed maturities | Merchandise Trusts | Corporate debt securities | Level 2
Schedule Of Available For Sale Securities [Line Items]
Cost		2,818
Gross Unrealized Gains	1	638
Fair Value	1	3,456
Variable Interest Entity, Primary Beneficiary | Fixed maturities | Merchandise Trusts | Other Debt Securities | Level 2
Schedule Of Available For Sale Securities [Line Items]
Cost		23,165
Gross Unrealized Gains		1,578
Gross Unrealized Losses		(1,332)
Fair Value		23,411
Variable Interest Entity, Primary Beneficiary | Mutual funds - debt securities | Merchandise Trusts | Level 1
Schedule Of Available For Sale Securities [Line Items]
Cost	6,097	6,097
Gross Unrealized Gains	81	306
Gross Unrealized Losses	(15)
Fair Value	6,163	6,403
Variable Interest Entity, Primary Beneficiary | Mutual funds - equity securities | Merchandise Trusts | Level 1
Schedule Of Available For Sale Securities [Line Items]
Cost	1,021	26,356
Gross Unrealized Gains	245	43
Gross Unrealized Losses		(154)
Fair Value	1,266	26,245
Variable Interest Entity, Primary Beneficiary | Other investment funds | Merchandise Trusts
Schedule Of Available For Sale Securities [Line Items]
Cost	457,447	337,565
Gross Unrealized Gains	26,008	32,461
Gross Unrealized Losses	(4,398)	(8,812)
Fair Value	479,057	361,214
Variable Interest Entity, Primary Beneficiary | Equity securities | Merchandise Trusts | Level 1
Schedule Of Available For Sale Securities [Line Items]
Cost	14,696	35,055
Gross Unrealized Gains	3,316	5,544
Gross Unrealized Losses	(2,051)	(19)
Fair Value	15,961	40,580
Variable Interest Entity, Primary Beneficiary | Other invested assets | Merchandise Trusts | Level 2
Schedule Of Available For Sale Securities [Line Items]
Cost	3,766	3,875
Gross Unrealized Gains	103	79
Fair Value	3,869	3,954
Variable Interest Entity, Primary Beneficiary | Total investments | Merchandise Trusts
Schedule Of Available For Sale Securities [Line Items]
Cost	534,271	475,971
Gross Unrealized Gains	29,754	40,661
Gross Unrealized Losses	(6,464)	(10,317)
Fair Value	557,561	506,315
Variable Interest Entity, Primary Beneficiary | West Virginia Trust Receivable | Merchandise Trusts
Schedule Of Available For Sale Securities [Line Items]
Cost	9,992	10,190
Gross Unrealized Gains	300
Gross Unrealized Losses		(221)
Fair Value	$ 10,292	$ 9,969