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, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Equity Investments [Abstract]
Revenues	$ 371	$ 339	$ 747	$ 672
Operating costs and expenses	317	297	633	591
Income from continuing operations before taxes	$ 54	$ 42	$ 114	$ 81