SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Workforce Optimization (Details) $ / shares in Units, $ in Millions	3 Months Ended	12 Months Ended
Sep. 30, 2017 employee	Dec. 31, 2017 USD ($) $ / shares	Dec. 31, 2018 USD ($)
Accounting Policies [Abstract]
Expected number of associates impacted \| employee	3,600
Expected percentage of workforce associates impacted	7.80%
Estimated charges		$ 148
Estimated charged per diluted share (in dollars per share) \| $ / shares		$ 0.64
Workforce optimization liability		$ 140	$ 12

Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

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-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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