Intangible Assets and Goodwill (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Goodwill [Line Items]
Impairment of intangible assets	$ 0	$ 31	$ 0	$ 31	$ 0
Amortization of Intangible Assets	80		$ 82	240	$ 242
Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year	80			80
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	320			320
Finite-Lived Intangible Assets, Amortization Expense, Year Two	320			320
Finite-Lived Intangible Assets, Amortization Expense, Year Three	320			320
Finite-Lived Intangible Assets, Amortization Expense, Year Four	320			320
Finite-Lived Intangible Assets, Amortization Expense, Year Five	$ 320			$ 320