Stockholders' Equity - Stock-based Compensation Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-Based Compensation Arrangement By Share-Based Payment Award, Fair Value Assumptions, Forfeiture Rate	27.00%		27.00%		27.00%
Total stock-based compensation expense	$ 2,601	$ 1,971	$ 4,358	$ 3,245
Cost of sales
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	76	43	118	67
Fulfillment
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	417	360	677	594
Technology and content
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	1,421	1,077	2,382	1,752
Marketing
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	456	307	787	516
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 231	$ 184	$ 394	$ 316