LONG-TERM DEBT - Covenants and Guarantees (Details) $ in Billions	3 Months Ended	12 Months Ended
	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Financial covenants
Interest Coverage Ratio		3.3
Indebtedness that could be declared immediately due and payable	$ 1.1	$ 1.2
Guarantees
Ownership of subsidiaries (as a percent)	100.00%
Minimum
Financial covenants
Interest Coverage Ratio	2.5
Note and Guarantee Agreement
Financial covenants
Ratio under debt agreement for entity to make dividends (as a percent)	60.00%
Sinosure Credit Facility | Term Loan
Financial covenants
Dividend cap as a percentage of consolidated net income	50.00%
Korean Export Credit Facility | Term Loan
Financial covenants
Dividend cap as a percentage of consolidated net income	50.00%
Refinancing Facility | Term Loan
Financial covenants
Dividend cap as a percentage of consolidated net income	50.00%