MERCHANDISE TRUSTS - Additional Information (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2021 USD ($) security	Jun. 30, 2020 USD ($) security	Dec. 31, 2020 USD ($)
West Virginia Trust Receivable
Schedule Of Available For Sale Securities [Line Items]
Trust assets, fair value	$ 10,400		$ 10,000
Merchandise Trusts
Schedule Of Available For Sale Securities [Line Items]
Percentage of VIE for cancellable state	48.20%
Merchandise Trusts | Variable Interest Entity, Primary Beneficiary
Schedule Of Available For Sale Securities [Line Items]
Trust assets, fair value	$ 544,268		516,284
Purchases of available for sale securities	36,600	$ 23,000
Sales, maturities and paydowns of available for sale securities	32,600	25,500
Other than temporary impairments loss	$ 136	$ 1,655
Merchandise Trusts | Variable Interest Entity, Primary Beneficiary | Other Than Temporarily Impaired Securities
Schedule Of Available For Sale Securities [Line Items]
Number of securities that incurred other than temporary impairment losses | security	6	2
Trust assets, cost	$ 300	$ 16,800
Trust assets, fair value	200	15,100
Other than temporary impairments loss	100	$ 1,700
Merchandise Trusts | West Virginia Trust Receivable | Variable Interest Entity, Primary Beneficiary
Schedule Of Available For Sale Securities [Line Items]
Trust assets, fair value	$ 10,387		$ 9,969