Equity Investments (Schedule of Financial Information Related to Unconsolidated Entities Included in Consolidated Statement of Income) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Equity Investments [Abstract]
Revenues	$ 176	$ 371	$ 592	$ 747
Operating costs and expenses	149	317	473	633
Income from continuing operations before taxes	$ 27	$ 54	$ 119	$ 114