DEBT - Schedule of Long-term Debt (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2020	Dec. 31, 2019
Debt
Outstanding long-term debt	$ 4,352	$ 4,977
Less: Current portion of long-term debt	0	(100)
Less: Amounts reclassified to LSTC	(4,352)	0
Total long-term debt	0	4,877
Line of Credit \| Revolving Credit Facility
Debt
Outstanding long-term debt	0	518
Line of Credit \| 2017 Credit Agreement
Debt
Outstanding long-term debt	1,300	1,300
Line of Credit \| 2016 Credit Agreement
Debt
Outstanding long-term debt	$ 1,000	1,000
Line of Credit \| LIBOR \| 2017 Credit Agreement
Debt
Interest rate added to variable rate basis	4.75%
Line of Credit \| LIBOR \| 2016 Credit Agreement
Debt
Interest rate added to variable rate basis	10.375%
Line of Credit \| LIBOR \| Minimum \| Revolving Credit Facility
Debt
Interest rate added to variable rate basis	3.25%
Line of Credit \| LIBOR \| Maximum \| Revolving Credit Facility
Debt
Interest rate added to variable rate basis	4.00%
Line of Credit \| Alternative Base Rate \| 2017 Credit Agreement
Debt
Interest rate added to variable rate basis	3.75%
Line of Credit \| Alternative Base Rate \| 2016 Credit Agreement
Debt
Interest rate added to variable rate basis	9.375%
Line of Credit \| Alternative Base Rate \| Minimum \| Revolving Credit Facility
Debt
Interest rate added to variable rate basis	2.25%
Line of Credit \| Alternative Base Rate \| Maximum \| Revolving Credit Facility
Debt
Interest rate added to variable rate basis	3.00%
Second Lien Notes \| Lien Notes
Debt
Outstanding long-term debt	$ 1,808	1,815
Debt instrument, interest rate, stated percentage	8.00%
5% Senior Notes due 2020 \| Senior Notes (Unsecured)
Debt
Outstanding long-term debt	$ 0	100
Debt instrument, interest rate, stated percentage	5.00%
5.5% Senior Notes due 2021 \| Senior Notes (Unsecured)
Debt
Outstanding long-term debt	$ 100	100
Debt instrument, interest rate, stated percentage	5.50%
6% Senior Notes due 2024 \| Senior Notes (Unsecured)
Debt
Outstanding long-term debt	$ 144	$ 144
Debt instrument, interest rate, stated percentage	6.00%

Long-Term Debt, Amount Reclassified

No definition available.

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- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=120520924&loc=SL6031897-161870

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-Section S99
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-Name Accounting Standards Codification
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- References

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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Topic 210
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-Section S99
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- Definition

Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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