INCOME TAXES - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax [Line Items]
Measurement period adjustment, additional deferred tax expense under the Act			$ 103
Increase (decrease) of valuation allowances	$ 1,000	$ 1,000	131
Net interest expense carryforward	1,100
Capital losses	633	626
Foreign tax credit carryforward, amount	2,241	2,241
Tax expense recorded for interest and penalties	1	1	1
Accrued for payment of interest and penalties	3	2	1
(Reduction) increase reserve for uncertain tax positions related to the current year	11	$ 58	$ 2
U.S.
Income Tax [Line Items]
Operating loss carryforwards	8,859
Operating loss carryforwards subject to annual limitation	186
Capital losses	$ 1,800
Capital loss carryforward carryover period	5 years
Canada
Income Tax [Line Items]
Capital losses	$ 836