Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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

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Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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Amount of cash outflow for cost from early extinguishment and prepayment of debt. Includes, but is not limited to, third-party cost, premium paid, and other fee paid to lender directly for debt extinguishment or debt prepayment. Excludes accrued interest.

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DEBT - Notes and Debentures (Details) - USD ($) $ in Millions					12 Months Ended
	Dec. 19, 2019	Apr. 16, 2018	Jun. 27, 2017	Jun. 21, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt
Repayments of notes payable					$ 201	$ 114	$ 535
Proceeds from issuance of debt				$ 599
Debt extinguishment costs					2	0	104
Debt extinguishment costs					$ 2	0	104
6.625% Notes and Debentures Due 15 April 2018
Debt
Interest rate (as a percent)		6.625%
Repayments of notes payable		$ 114
7.75% Notes and Debentures Due 1 August 2029 \| Senior notes and debentures
Debt
Interest rate (as a percent)			7.75%		7.75%
Repayments of notes payable			$ 62
Senior Notes					$ 235	235
3.5% Notes and Debentures Due November 15, 2027
Debt
Interest rate (as a percent)					3.50%
3.5% Notes and Debentures Due November 15, 2027 \| Senior notes and debentures
Debt
Interest rate (as a percent)				3.50%
Long-term debt, gross				$ 300
Senior Notes					$ 300	300
4.5% Notes and Debentures Due May 15, 2047 \| Senior notes and debentures
Debt
Interest rate (as a percent)				4.50%	4.50%
Long-term debt, gross				$ 300
Senior Notes					$ 299	299
7.125% Notes and Debentures Due 15 March 2020
Debt
Debt extinguishment costs	$ 2
7.125% Notes and Debentures Due 15 March 2020 \| Senior notes and debentures
Debt
Interest rate (as a percent)	7.125%		7.125%		7.125%
Repayments of notes payable	$ 201		$ 299
Senior Notes					$ 0	201
5.95% Notes and Debentures Due March 15, 2022 [Member] \| Senior notes and debentures
Debt
Interest rate (as a percent)			5.95%
Repayments of notes payable			$ 74
6.5% Notes and Debentures Due 15 August 2032 \| Senior notes and debentures
Debt
Interest rate (as a percent)			6.50%		6.50%
Repayments of notes payable			$ 100
Senior Notes					$ 200	200
7.125%, 5.95%, 7.75% and 6.5% Notes and Debentures [Member]
Debt
Debt extinguishment costs							$ 107
3.5% Notes and Debentures Due April 1, 2021
Debt
Interest rate (as a percent)					3.50%
3.5% Notes and Debentures Due April 1, 2021 \| Senior notes and debentures
Debt
Senior Notes					$ 399	399
4.375% Notes and Debentures Due April 1, 2026
Debt
Interest rate (as a percent)					4.375%
4.375% Notes and Debentures Due April 1, 2026 \| Senior notes and debentures
Debt
Senior Notes					$ 498	498
4.45% Notes and Debentures Due 1 April 2025 \| Senior notes and debentures
Debt
Interest rate (as a percent)					4.45%
Senior Notes					$ 500	$ 500