MERCHANDISE TRUSTS - Aging of Unrealized Losses on Investments in Fixed Maturities and Equity Securities Held in Merchandise Trusts (Detail) - Variable Interest Entity, Primary Beneficiary - Merchandise Trusts - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Unrealized Losses	$ 48,448	$ 2,993
12 Months or more Unrealized Losses	1,838	168
Total Unrealized Losses	50,286	3,161
Less than 12 months Fair Value	157,325	55,314
12 Months or more Fair Value	920	821
Total Fair Value	158,245	56,135
Fixed maturities
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Unrealized Losses	668	30
12 Months or more Unrealized Losses	188	168
Total Unrealized Losses	856	198
Less than 12 months Fair Value	18,259	288
12 Months or more Fair Value	917	821
Total Fair Value	19,176	1,109
Fixed maturities | U.S. governmental securities
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Unrealized Losses		1
12 Months or more Unrealized Losses	61	64
Total Unrealized Losses	61	65
Less than 12 months Fair Value	29	90
12 Months or more Fair Value	297	397
Total Fair Value	326	487
Fixed maturities | Corporate debt securities
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Unrealized Losses	2	29
12 Months or more Unrealized Losses	127	104
Total Unrealized Losses	129	133
Less than 12 months Fair Value	172	198
12 Months or more Fair Value	620	424
Total Fair Value	792	622
Fixed maturities | Other Debt Securities
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Unrealized Losses	666
Total Unrealized Losses	666
Less than 12 months Fair Value	18,058
Total Fair Value	18,058
Mutual funds - debt securities
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Unrealized Losses	258	6
12 Months or more Unrealized Losses	333
Total Unrealized Losses	591	6
Less than 12 months Fair Value	9,684	241
Total Fair Value	9,684	241
Mutual funds - equity securities
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Unrealized Losses	20,252
12 Months or more Unrealized Losses	1,226
Total Unrealized Losses	21,478
Less than 12 months Fair Value	21,160
Total Fair Value	21,160
Other investment funds
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Unrealized Losses	11,521	2,953
Total Unrealized Losses	11,521	2,953
Less than 12 months Fair Value	87,421	54,782
Total Fair Value	87,421	54,782
Equity securities
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Unrealized Losses	15,749	4
12 Months or more Unrealized Losses	1
Total Unrealized Losses	15,750	4
Less than 12 months Fair Value	20,801	3
12 Months or more Fair Value	3
Total Fair Value	20,804	$ 3
Other invested assets
Investments, Unrealized Loss Position [Line Items]
12 Months or more Unrealized Losses	90
Total Unrealized Losses	$ 90