STOCKHOLDERS' EQUITY AND STOCK-BASED COMPENSATION (Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, stockholders' equity	$ 9,298
Ending balance, stockholders' equity	10,174	$ 9,298
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), after Reclassification Adjustment, before Tax	40	(111)	$ (87)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, stockholders' equity	(686)	(615)	(494)
OCI, before Reclassifications, Net of Tax, Attributable to Parent	47	(118)	(84)
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, Net of Tax	46	47	48
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Investment Transferred from Available-for-sale to Equity Method, Tax			(6)
Ending balance, stockholders' equity	(593)	(686)	(615)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] | Accounting Standards Update 2018-02
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, stockholders' equity		(79)
Ending balance, stockholders' equity			(79)
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, stockholders' equity	0	0	(3)
OCI, before Reclassifications, Net of Tax, Attributable to Parent	0	0	0
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, Net of Tax	0	0	3
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Investment Transferred from Available-for-sale to Equity Method, Tax			0
Ending balance, stockholders' equity	0	0	0
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member] | Accounting Standards Update 2018-02
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, stockholders' equity		0
Ending balance, stockholders' equity			0
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, stockholders' equity	10	10	10
OCI, before Reclassifications, Net of Tax, Attributable to Parent	0	0	0
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, Net of Tax	0	0	0
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Investment Transferred from Available-for-sale to Equity Method, Tax			0
Ending balance, stockholders' equity	10	10	10
Accumulated Foreign Currency Adjustment Attributable to Parent [Member] | Accounting Standards Update 2018-02
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, stockholders' equity		0
Ending balance, stockholders' equity			0
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, stockholders' equity	(676)	(605)	(487)
OCI, before Reclassifications, Net of Tax, Attributable to Parent	47	(118)	(84)
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, Net of Tax	46	47	51
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Investment Transferred from Available-for-sale to Equity Method, Tax			(6)
Ending balance, stockholders' equity	(583)	(676)	(605)
Accumulated Other Comprehensive Loss | Accounting Standards Update 2018-02
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, stockholders' equity		(79)
Ending balance, stockholders' equity			(79)
Accumulated Defined Benefit Plans Adjustment Attributable to Noncontrolling Interest [Member]
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	(7)	8	(4)
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, Net of Tax	0
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member] | Maximum
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, Net of Tax	$ (1)	$ (1)	$ (1)