Goodwill, Intangibles and Other Assets (Narrative) (Details)	12 Months Ended
	Dec. 31, 2017
Olefins [Member]
Other Assets [Line Items]
Number of years forecasted to test for impairment of goodwill	9 years
Olefins [Member] | Discounted Cash Flow and Market Approach Valuation Technique [Member]
Other Assets [Line Items]
Discount rate	8.00%
Vinyls [Member]
Other Assets [Line Items]
Number of years forecasted to test for impairment of goodwill	9 years
Vinyls [Member] | Market Approach Valuation Technique [Member] | Minimum [Member]
Other Assets [Line Items]
Discount rate	9.00%
Vinyls [Member] | Market Approach Valuation Technique [Member] | Maximum [Member]
Other Assets [Line Items]
Discount rate	12.00%