Equity Investments (Schedule of Financial Information Related to Unconsolidated Entities Included in Consolidated Statement of Income) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Equity Investments [Abstract]
Revenues	$ 1,368	$ 1,246	$ 1,237
Operating costs and expenses	1,184	1,117	1,079
Income from continuing operations before taxes	$ 184	$ 130	$ 158