Stockholders’ Equity - Summary of Stock Repurchase Activity (Details) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2019 USD ($) $ / shares shares
Equity [Abstract]
Shares Repurchased (in shares) | shares	107,000,000
Average Price per Share (in usd per share) | $ / shares	$ 37.53
Value of Shares Repurchased	$ 4,000
Shares Repurchased, Remaining Amount Authorized
Beginning balance	3,151
Repurchase of shares of common stock	(4,000)
Ending balance	$ 3,151
Treasury shares retired (in shares) | shares	0