Common Stock (Details) - USD ($)	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Nov. 30, 2016
Equity, Class of Treasury Stock [Line Items]
Payments for repurchase of common stock	$ 100,000,000	$ 500,000,000
Stock-based compensation, shares issued during period	3,800,000	2,500,000
Common Stock
Equity, Class of Treasury Stock [Line Items]
Common stock repurchased (in shares)	1,000,000.0	6,100,000
Payments for repurchase of common stock	$ 100,000,000	$ 500,000,000
Share repurchases program, authorized amount (up to)			$ 2,500,000,000
Stock repurchase program, remaining authorized repurchase amount	$ 766,000,000