SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Summary of Significant Accounting Policies - Other Non-Current Liabilities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Non-Current Liabilities [Line Items]
Deferred Income Tax Expense (Benefit)	$ (249)
Liability, Other Retirement Benefits, Noncurrent	120	$ 96
Asset Retirement Obligation	57	54	$ 58	$ 58
Other Accrued Liabilities, Current	64	67
Other Liabilities, Noncurrent	$ 241	$ 217