MERCHANDISE TRUSTS - Additional Information (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2020 USD ($) security	Jun. 30, 2019 USD ($) security	Dec. 31, 2019 USD ($)
West Virginia Trust Receivable
Schedule Of Available For Sale Securities [Line Items]
Trust assets, fair value	$ 9,300		$ 9,700
Merchandise Trusts
Schedule Of Available For Sale Securities [Line Items]
Percentage of VIE for cancellable state	51.40%
Merchandise Trusts | Variable Interest Entity, Primary Beneficiary
Schedule Of Available For Sale Securities [Line Items]
Trust assets, fair value	$ 484,308		523,865
Purchases of available for sale securities	23,000	$ 29,100
Sales, maturities and paydowns of available for sale securities	25,500	19,900
Other than temporary impairments loss	$ 1,655	$ 2,314
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	2	89
Trust assets, cost	$ 16,800	$ 91,900
Trust assets, fair value	15,100	89,600
Other than temporary impairments loss	1,700	$ 2,300
Merchandise Trusts | West Virginia Trust Receivable | Variable Interest Entity, Primary Beneficiary
Schedule Of Available For Sale Securities [Line Items]
Trust assets, fair value	$ 9,293		$ 9,651