MERCHANDISE TRUSTS - Cost and Market Value Associated with Assets Held in Merchandise Trusts (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
West Virginia Trust Receivable
Schedule Of Available For Sale Securities [Line Items]
Fair Value	$ 9,900	$ 10,300
Variable Interest Entity, Primary Beneficiary | Merchandise Trusts
Schedule Of Available For Sale Securities [Line Items]
Cost	558,471	544,263
Gross Unrealized Gains	37,805	30,054
Gross Unrealized Losses	(6,509)	(6,464)
Fair Value	589,767	567,853
Variable Interest Entity, Primary Beneficiary | Short-term investments | Merchandise Trusts | Level 1
Schedule Of Available For Sale Securities [Line Items]
Cost	43,112	51,243
Fair Value	43,112	51,243
Variable Interest Entity, Primary Beneficiary | Fixed maturities | Merchandise Trusts
Schedule Of Available For Sale Securities [Line Items]
Cost	1	1
Gross Unrealized Gains		1
Fair Value	1	2
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]
Gross Unrealized Gains		1
Fair Value		1
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	19	81
Gross Unrealized Losses	(303)	(15)
Fair Value	5,813	6,163
Variable Interest Entity, Primary Beneficiary | Mutual funds - equity securities | Merchandise Trusts | Level 1
Schedule Of Available For Sale Securities [Line Items]
Cost	1,022	1,021
Gross Unrealized Gains	213	245
Fair Value	1,235	1,266
Variable Interest Entity, Primary Beneficiary | Other investment funds | Merchandise Trusts
Schedule Of Available For Sale Securities [Line Items]
Cost	479,490	457,447
Gross Unrealized Gains	31,690	26,008
Gross Unrealized Losses	(3,908)	(4,398)
Fair Value	507,272	479,057
Variable Interest Entity, Primary Beneficiary | Equity securities | Merchandise Trusts | Level 1
Schedule Of Available For Sale Securities [Line Items]
Cost	15,017	14,696
Gross Unrealized Gains	5,814	3,316
Gross Unrealized Losses	(2,170)	(2,051)
Fair Value	18,661	15,961
Variable Interest Entity, Primary Beneficiary | Other invested assets | Merchandise Trusts | Level 2
Schedule Of Available For Sale Securities [Line Items]
Cost	3,735	3,766
Gross Unrealized Gains	69	103
Fair Value	3,804	3,869
Variable Interest Entity, Primary Beneficiary | Total investments | Merchandise Trusts
Schedule Of Available For Sale Securities [Line Items]
Cost	548,474	534,271
Gross Unrealized Gains	37,805	29,754
Gross Unrealized Losses	(6,381)	(6,464)
Fair Value	579,898	557,561
Variable Interest Entity, Primary Beneficiary | West Virginia Trust Receivable | Merchandise Trusts
Schedule Of Available For Sale Securities [Line Items]
Cost	9,997	9,992
Gross Unrealized Gains		300
Gross Unrealized Losses	(128)
Fair Value	$ 9,869	$ 10,292