Basis of Presentation ASUs Implemented (Details) - USD ($) $ in Millions	Sep. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Abstract]
Other current liabilities	$ 340		$ 867
Other long-term liabilities	1,774		2,370
Other long-term assets	794		688
Deferred income taxes	428		$ 191
Accounting Standards Update 2016-16 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		$ 55
Accounting Standards Update 2014-09 [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		$ 177
Revenue, Initial Application Period Cumulative Effect Transition [Abstract]
Other current liabilities	59
Other long-term liabilities	205
Other long-term assets	12
Deferred income taxes	$ 41