SUBSEQUENT EVENTS (Details) - USD ($)		9 Months Ended		12 Months Ended
	Oct. 01, 2020	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2020	Dec. 31, 2019
Subsequent Event [Line Items]
Non-cash acceleration of amortization and accretion of premiums and discounts		$ (235,331,000)	$ (238,086,000)
Reserve funding agreement, obligations (up to)		2,942,126,000			$ 3,082,753,000
Golden Gate II Captive Insurance Company
Subsequent Event [Line Items]
Reserve funding agreement, obligations (up to)		275,895,000			274,955,000
Golden Gate II Captive Insurance Company | Forecast
Subsequent Event [Line Items]
Non-cash acceleration of amortization and accretion of premiums and discounts				$ 54,000,000
Golden Gate Captive Insurance Company
Subsequent Event [Line Items]
Reserve funding agreement, obligations (up to)		$ 1,858,000,000			$ 2,028,000,000
Red Mountain | Forecast
Subsequent Event [Line Items]
Non-cash acceleration of amortization and accretion of premiums and discounts				$ 16,000,000
Subsequent Event | Golden Gate Captive Insurance Company
Subsequent Event [Line Items]
Reserve funding agreement, obligations (up to)	$ 5,000,000,000
Subsequent Event | Golden Gate Captive Insurance Company | Minimum
Subsequent Event [Line Items]
Reserve funding agreement, term	20 years
Subsequent Event | Golden Gate Captive Insurance Company | Maximum
Subsequent Event [Line Items]
Reserve funding agreement, term	25 years