Goodwill and Intangible Assets (Schedules for Amortization Expense) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Finite Lived Intangible Asset
Amortization expense for acquired intangible assets	$ 47	$ 66	$ 111	$ 132
Expected amortization expense for acquired intangible assets recorded as of balance sheet date
Remainder of 2017	118		118
2018	190		190
2019	181		181
2020	172		172
2021	160		160
2022	147		147
After 2022	$ 593		$ 593