FINANCING ARRANGEMENTS - Summary of Consolidated Long-term Debt (Details) - USD ($)	Mar. 31, 2021	Dec. 31, 2020	Dec. 03, 2020	May 26, 2020
Long-term debt, net of unamortized debt discount
Principal Amount	$ 23,985,000,000	$ 24,185,000,000
Total long-term debt and other	23,738,000,000	23,925,000,000
Less: Current portion of long-term debt and other	0	0
Non-current portion of long-term debt	$ 23,738,000,000	23,925,000,000
Term Loan B Facility Due June 2025
Long-term debt, net of unamortized debt discount
Stated interest rate on debt (as a percent)	3.11%
Principal Amount	$ 3,298,000,000	3,298,000,000
Total long-term debt and other	$ 3,224,000,000	3,220,000,000
Term Loan B Facility Due November 2025
Long-term debt, net of unamortized debt discount
Stated interest rate on debt (as a percent)	2.86%
Principal Amount	$ 1,125,000,000	1,125,000,000
Total long-term debt and other	$ 1,112,000,000	1,112,000,000
Senior Secured Notes | 7.00% Senior Notes Due March 2024
Long-term debt, net of unamortized debt discount
Stated interest rate on debt (as a percent)	7.00%
Principal Amount	$ 1,800,000,000	2,000,000,000
Total long-term debt and other	$ 1,789,000,000	1,987,000,000
Senior Secured Notes | 5.50% Senior Notes Due November 2025
Long-term debt, net of unamortized debt discount
Stated interest rate on debt (as a percent)	5.50%
Principal Amount	$ 1,750,000,000	1,750,000,000
Total long-term debt and other	$ 1,737,000,000	1,736,000,000
Senior Secured Notes | 5.75% Senior Notes Due August 2027
Long-term debt, net of unamortized debt discount
Stated interest rate on debt (as a percent)	5.75%
Principal Amount	$ 500,000,000	500,000,000
Total long-term debt and other	$ 494,000,000	494,000,000
Senior Unsecured Notes | 6.125% Senior Notes Due April 2025
Long-term debt, net of unamortized debt discount
Stated interest rate on debt (as a percent)	6.125%
Principal Amount	$ 3,250,000,000	3,250,000,000
Total long-term debt and other	$ 3,234,000,000	3,234,000,000
Senior Unsecured Notes | 9.00% Senior Notes Due December 2025
Long-term debt, net of unamortized debt discount
Stated interest rate on debt (as a percent)	9.00%
Principal Amount	$ 1,500,000,000	1,500,000,000
Total long-term debt and other	$ 1,479,000,000	1,478,000,000
Senior Unsecured Notes | 9.25% Senior Notes Due April 2026
Long-term debt, net of unamortized debt discount
Stated interest rate on debt (as a percent)	9.25%
Principal Amount	$ 1,500,000,000	1,500,000,000
Total long-term debt and other	$ 1,488,000,000	1,487,000,000
Senior Unsecured Notes | 8.50% Senior Notes Due January 2027
Long-term debt, net of unamortized debt discount
Stated interest rate on debt (as a percent)	8.50%
Principal Amount	$ 1,750,000,000	1,750,000,000
Total long-term debt and other	$ 1,755,000,000	1,755,000,000
Senior Unsecured Notes | 7.00 % Senior Notes Due January 2028
Long-term debt, net of unamortized debt discount
Stated interest rate on debt (as a percent)	7.00%
Principal Amount	$ 750,000,000	750,000,000
Total long-term debt and other	$ 742,000,000	742,000,000
Senior Unsecured Notes | 5.00% Senior Notes Due January 2028
Long-term debt, net of unamortized debt discount
Stated interest rate on debt (as a percent)	5.00%
Principal Amount	$ 1,250,000,000	1,250,000,000
Total long-term debt and other	$ 1,236,000,000	1,236,000,000
Senior Unsecured Notes | 6.25% Senior Notes Due February 2029
Long-term debt, net of unamortized debt discount
Stated interest rate on debt (as a percent)	6.25%			6.25%
Principal Amount	$ 1,500,000,000	1,500,000,000
Total long-term debt and other	$ 1,481,000,000	1,480,000,000
Senior Unsecured Notes | 5.00% Senior Notes Due February 2029
Long-term debt, net of unamortized debt discount
Stated interest rate on debt (as a percent)	5.00%		5.00%
Principal Amount	$ 1,000,000,000	1,000,000,000
Total long-term debt and other	$ 989,000,000	988,000,000
Senior Unsecured Notes | 7.25 % Senior Notes Due May 2029
Long-term debt, net of unamortized debt discount
Stated interest rate on debt (as a percent)	7.25%
Principal Amount	$ 750,000,000	750,000,000
Total long-term debt and other	$ 742,000,000	741,000,000
Senior Unsecured Notes | 5.25% Senior Notes Due January 2030
Long-term debt, net of unamortized debt discount
Stated interest rate on debt (as a percent)	5.25%
Principal Amount	$ 1,250,000,000	1,250,000,000
Total long-term debt and other	$ 1,236,000,000	1,235,000,000
Senior Unsecured Notes | 5.25% Senior Notes Due February 2031
Long-term debt, net of unamortized debt discount
Stated interest rate on debt (as a percent)	5.25%		5.25%
Principal Amount	$ 1,000,000,000	1,000,000,000
Total long-term debt and other	988,000,000	988,000,000
Senior Unsecured Notes | Other
Long-term debt, net of unamortized debt discount
Principal Amount	12,000,000	12,000,000
Total long-term debt and other	$ 12,000,000	12,000,000
Revolving Credit Facility | Revolving Credit Facility Due June 2023
Long-term debt, net of unamortized debt discount
Stated interest rate on debt (as a percent)	3.11%
Principal Amount	$ 0	0
Total long-term debt and other	$ 0	$ 0