LONG-TERM DEBT - Senior Notes Narrative (Details) - USD ($)	Apr. 10, 2017	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2014
Debt Instrument
Principal amount		$ 1,500,000,000	$ 1,500,000,000
3.90% Senior Notes
Debt Instrument
Principal amount	$ 750,000,000	$ 750,000,000	750,000,000
Interest rate (as a percent)	3.90%	3.90%
Issuance price relative to par value (as a percent)	99.748%
Effective rate (as a percent)	3.93%	4.01%
4.375% Senior Notes
Debt Instrument
Principal amount		$ 750,000,000	$ 750,000,000	$ 750,000,000
Interest rate (as a percent)		4.375%		4.375%
Effective rate (as a percent)		4.50%