Acquisitions, Goodwill, and Acquired Intangible Assets - Summary of Goodwill Activity by Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Roll Forward]
Goodwill, balance at beginning of period	$ 13,350	$ 3,784
New acquisitions	1,228	9,501
Other adjustments	(30)	65
Goodwill, balance at end of period	14,548	13,350
North America
Goodwill [Roll Forward]
Goodwill, balance at beginning of period	11,165	2,044
New acquisitions	1,031	9,115
Other adjustments	(5)	6
Goodwill, balance at end of period	12,191	11,165
International
Goodwill [Roll Forward]
Goodwill, balance at beginning of period	1,108	694
New acquisitions	177	368
Other adjustments	(15)	46
Goodwill, balance at end of period	1,270	1,108
AWS
Goodwill [Roll Forward]
Goodwill, balance at beginning of period	1,077	1,046
New acquisitions	20	18
Other adjustments	(10)	13
Goodwill, balance at end of period	$ 1,087	$ 1,077