Other Financial Data - Other Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Other Liabilities [Abstract]
Defined benefit plans	$ 1,797	$ 1,799
Deferred revenue	158	115
Unrecognized tax benefits	40	39
Deferred income taxes	142	121
Deferred consideration (Note 13)	82	72
Other	231	209
Other liabilities	$ 2,450	$ 2,355