INVESTMENTS - Equity Securities (Details) - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2019	Dec. 31, 2018
Equity Securities, FV-NI [Line Items]
Document Period End Date	Jun. 30, 2019
Fair Value	$ 1,087	$ 987
Yen-denominated
Equity Securities, FV-NI [Line Items]
Fair Value	679	641
Dollar-denominated
Equity Securities, FV-NI [Line Items]
Fair Value	$ 408	$ 346

Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=99377092&loc=SL75136599-209740

Name:	us-gaap_EquitySecuritiesFvNi
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant