Stockholders' Equity - Stock Repurchase Program (Details) shares in Millions	Sep. 30, 2019 USD ($) shares
Class of Stock [Line Items]
Number of shares repurchased (in shares) | shares	3,018
Aggregate cost for shares repurchased	$ 12,640,000,000
Remaining amount authorized under the stock repurchase program	1,360,000,000
Common Stock
Class of Stock [Line Items]
Stock repurchase program, aggregate authorized amount	$ 14,000,000,000