Goodwill and Other Intangible Assets (Schedule of Goodwill) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Roll Forward]
Balance at beginning of year	$ 1,012	$ 947
Goodwill, Purchase Accounting Adjustments		55
Effects of changes in foreign exchange rates	(10)	10
Balance at end of year	1,002	1,012
Olefins [Member]
Goodwill [Roll Forward]
Balance at beginning of year	30	30
Goodwill, Purchase Accounting Adjustments		0
Effects of changes in foreign exchange rates	0	0
Balance at end of year	30	30
Vinyls [Member]
Goodwill [Roll Forward]
Balance at beginning of year	982	917
Goodwill, Purchase Accounting Adjustments		55
Effects of changes in foreign exchange rates	(10)	10
Balance at end of year	$ 972	$ 982