DEBT - Senior Notes (Details) - Senior Notes - USD ($)	1 Months Ended	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2017	Dec. 31, 2016	Oct. 31, 2014	Dec. 31, 2008
Debt Instrument [Line Items]
Total long-term debt	$ 4,780,000,000	$ 4,780,000,000	$ 3,792,000,000
Proceeds from debt, net of discounts and offering expenses	$ 991,000,000
Redemption price, percentage		100.00%
Unamortized discount (premium)					$ 103,000,000
$500 million, 7.20% due June 15, 2018
Debt Instrument [Line Items]
Stated interest rate	7.20%	7.20%
Face amount	$ 500,000,000	$ 500,000,000
Total long-term debt	$ 501,000,000	$ 501,000,000	501,000,000
$300 million, 6.30% due August 1, 2018
Debt Instrument [Line Items]
Stated interest rate	6.30%	6.30%
Face amount	$ 300,000,000	$ 300,000,000
Total long-term debt	$ 304,000,000	$ 304,000,000	304,000,000
$400 million, 2.625% due October 1, 2019
Debt Instrument [Line Items]
Stated interest rate	2.625%	2.625%
Face amount	$ 400,000,000	$ 400,000,000
Total long-term debt	$ 398,000,000	$ 398,000,000	398,000,000
$600 million, 3.15% due December 1, 2022
Debt Instrument [Line Items]
Stated interest rate	3.15%	3.15%
Face amount	$ 600,000,000	$ 600,000,000
Total long-term debt	$ 595,000,000	$ 595,000,000	595,000,000
$600 million, 3.85% due October 1, 2024
Debt Instrument [Line Items]
Stated interest rate	3.85%	3.85%
Face amount	$ 600,000,000	$ 600,000,000
Total long-term debt	$ 595,000,000	$ 595,000,000	595,000,000
$600 million, 3.95% due March 15, 2027
Debt Instrument [Line Items]
Stated interest rate	3.95%	3.95%
Face amount	$ 600,000,000	$ 600,000,000
Total long-term debt	$ 594,000,000	$ 594,000,000	0
$250 million, 8.15% due June 15, 2038
Debt Instrument [Line Items]
Stated interest rate	8.15%	8.15%
Face amount	$ 250,000,000	$ 250,000,000
Total long-term debt	$ 263,000,000	$ 263,000,000	264,000,000
$400 million, 4.625% due December 1, 2042
Debt Instrument [Line Items]
Stated interest rate	4.625%	4.625%
Face amount	$ 400,000,000	$ 400,000,000
Total long-term debt	$ 396,000,000	$ 396,000,000	396,000,000
$750 million, 4.95% due October 1, 2044
Debt Instrument [Line Items]
Stated interest rate	4.95%	4.95%
Face amount	$ 750,000,000	$ 750,000,000
Total long-term debt	$ 739,000,000	$ 739,000,000	739,000,000
$400 million, 4.80% due March 15, 2047
Debt Instrument [Line Items]
Stated interest rate	4.80%	4.80%
Face amount	$ 400,000,000	$ 400,000,000
Total long-term debt	$ 395,000,000	$ 395,000,000	0
6.45% Senior Notes due June 2016
Debt Instrument [Line Items]
Stated interest rate	6.45%	6.45%
Unamortized discount (premium)	$ 22,000,000	$ 22,000,000	$ 23,000,000	$ 12,000,000