MERCHANDISE TRUSTS - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) security	Dec. 31, 2018 USD ($) security
West Virginia Trust Receivable
Schedule Of Available For Sale Securities [Line Items]
Trust assets, fair value	$ 9,700	$ 8,700
Merchandise Trusts
Schedule Of Available For Sale Securities [Line Items]
Percentage of VIE for cancellable state	53.60%
Merchandise Trusts | Variable Interest Entity, Primary Beneficiary
Schedule Of Available For Sale Securities [Line Items]
Trust assets, fair value	$ 523,865	488,248
Purchases of available for sale securities	54,400	117,700
Sales, maturities and paydowns of available for sale securities	$ 38,100	$ 109,500
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	102	214
Trust assets, cost	$ 178,200	$ 285,500
Trust assets, fair value	172,200	256,900
Other than temporary impairments loss	6,100	28,600
Merchandise Trusts | West Virginia Trust Receivable | Variable Interest Entity, Primary Beneficiary
Schedule Of Available For Sale Securities [Line Items]
Trust assets, fair value	$ 9,651	$ 8,663