MERCHANDISE TRUSTS - Cost and Market Value Associated with Assets Held in Merchandise Trusts (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
West Virginia Trust Receivable
Schedule Of Available For Sale Securities [Line Items]
Fair Value	$ 9,400	$ 10,300
Variable Interest Entity, Primary Beneficiary | Merchandise Trusts
Schedule Of Available For Sale Securities [Line Items]
Cost	566,073	544,263
Gross Unrealized Gains	46,821	30,054
Gross Unrealized Losses	(8,134)	(6,464)
Fair Value	604,760	567,853
Variable Interest Entity, Primary Beneficiary | Short-term investments | Merchandise Trusts | Level 1
Schedule Of Available For Sale Securities [Line Items]
Cost	33,580	51,243
Fair Value	33,580	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		81
Gross Unrealized Losses	(647)	(15)
Fair Value	5,450	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	31	245
Gross Unrealized Losses	(7)
Fair Value	1,046	1,266
Variable Interest Entity, Primary Beneficiary | Other investment funds | Merchandise Trusts
Schedule Of Available For Sale Securities [Line Items]
Cost	496,349	457,447
Gross Unrealized Gains	42,859	26,008
Gross Unrealized Losses	(4,530)	(4,398)
Fair Value	534,678	479,057
Variable Interest Entity, Primary Beneficiary | Equity securities | Merchandise Trusts | Level 1
Schedule Of Available For Sale Securities [Line Items]
Cost	14,687	14,696
Gross Unrealized Gains	3,863	3,316
Gross Unrealized Losses	(2,040)	(2,051)
Fair Value	16,510	15,961
Variable Interest Entity, Primary Beneficiary | Other invested assets | Merchandise Trusts | Level 2
Schedule Of Available For Sale Securities [Line Items]
Cost	4,053	3,766
Gross Unrealized Gains	68	103
Fair Value	4,121	3,869
Variable Interest Entity, Primary Beneficiary | Total investments | Merchandise Trusts
Schedule Of Available For Sale Securities [Line Items]
Cost	555,789	534,271
Gross Unrealized Gains	46,821	29,754
Gross Unrealized Losses	(7,224)	(6,464)
Fair Value	595,386	557,561
Variable Interest Entity, Primary Beneficiary | West Virginia Trust Receivable | Merchandise Trusts
Schedule Of Available For Sale Securities [Line Items]
Cost	10,284	9,992
Gross Unrealized Gains		300
Gross Unrealized Losses	(910)
Fair Value	$ 9,374	$ 10,292