Earnings Per Share - Schedule of Anti Dilutive Securities Excluded From Computation of Weighted Average Shares Outstanding (Details) - $ / shares shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Mandatory convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive securities (in shares)	0	39	0	0
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive securities (in shares)	6	3	6	3
Weighted average exercise price of options (in usd per share)	$ 29.14	$ 33.33	$ 29.14	$ 33.33