Organization and Basis of Presentation (New Accounting Standards) (Details) - Accounting Standards Update 2017-07 [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating income and expenses, net [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New accounting pronouncement, quantified affect	$ 156	$ 131	$ 96
Nonoperating income and expenses, net [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New accounting pronouncement, quantified affect	$ 156	$ 131	$ 96