Equity Investments (Schedule of Financial Information Related to Unconsolidated Entities Included in Consolidated Statement of Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Equity Investments [Abstract]
Revenues	$ 731	$ 1,494	$ 1,368
Operating costs and expenses	602	1,287	1,184
Income from continuing operations before taxes	$ 129	$ 207	$ 184