STATUTORY REPORTING PRACTICES AND OTHER REGULATORY MATTERS - Schedule of Effects on Statutory Surplus (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Statutory Accounting Practices Disclosure of Favorable (Unfavorable) Effects of Statutory Surplus [Abstract]
Non-admission of goodwill	$ (105,000)	$ (143,000)
Total (net)	(105,000)	(143,000)
Insurance subsidiaries
Statutory Accounting Practices Disclosure of Favorable (Unfavorable) Effects of Statutory Surplus [Abstract]
Total (net)	4,455,000	4,348,000
Statutory Accounting Practices Disclosure of Favorable (Unfavorable) Effects on Statutory Surplus of Insurance Subsidiaries [Abstract]
Accounting for Letters of Credit as admitted assets	0	1,555,000
Accounting for XOL Asset Value as an admitted asset	4,579,000	0
Accounting for certain notes as admitted assets	0	2,748,000
Reserving based on state specific actuarial practices	94,000	116,000
Reserving difference related to a captive insurance company	$ (218,000)	$ (71,000)