DEBT - Senior Notes (Details) - Senior Notes - USD ($)	1 Months Ended	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Long-term debt		$ 4,772,000,000	$ 4,770,000,000
Proceeds from debt, net of discounts and offering expenses	$ 991,000,000
Redemption price, percentage		100.00%
$400 million, 2.625% due October 1, 2019
Debt Instrument [Line Items]
Long-term debt		$ 399,000,000	399,000,000
Face amount		$ 400,000,000
Stated interest rate		2.625%
$400 million, 2.50% due December 15, 2020
Debt Instrument [Line Items]
Long-term debt		$ 397,000,000	397,000,000
Face amount		$ 400,000,000
Stated interest rate		2.50%
$400 million, 2.90% due December 15, 2022
Debt Instrument [Line Items]
Long-term debt		$ 396,000,000	396,000,000
Face amount		$ 400,000,000
Stated interest rate		2.90%
$600 million, 3.15% due December 1, 2022
Debt Instrument [Line Items]
Long-term debt		$ 596,000,000	595,000,000
Face amount		$ 600,000,000
Stated interest rate		3.15%
$600 million, 3.85% due October 1, 2024
Debt Instrument [Line Items]
Long-term debt		$ 596,000,000	595,000,000
Face amount		$ 600,000,000
Stated interest rate		3.85%
$600 million, 3.95% due March 15, 2027
Debt Instrument [Line Items]
Long-term debt		$ 595,000,000	594,000,000
Face amount	$ 600,000,000	$ 600,000,000
Stated interest rate	3.95%	3.95%
$250 million, 8.15% due June 15, 2038
Debt Instrument [Line Items]
Long-term debt		$ 263,000,000	263,000,000
Face amount		$ 250,000,000
Stated interest rate		8.15%
$400 million, 4.625% due December 1, 2042
Debt Instrument [Line Items]
Long-term debt		$ 396,000,000	396,000,000
Face amount		$ 400,000,000
Stated interest rate		4.625%
$750 million, 4.95% due October 1, 2044
Debt Instrument [Line Items]
Long-term debt		$ 739,000,000	739,000,000
Face amount		$ 750,000,000
Stated interest rate		4.95%
$400 million, 4.80% due March 15, 2047
Debt Instrument [Line Items]
Long-term debt		$ 395,000,000	$ 396,000,000
Face amount	$ 400,000,000	$ 400,000,000
Stated interest rate	4.80%	4.80%