Earnings Per Share - Schedule of Anti Dilutive Securities Excluded From Computation of Weighted Average Shares Outstanding (Detail) - $ / shares shares in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Mandatory convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive securities (in shares)	0	0
Convertible notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive securities (in shares)	0	0
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive securities (in shares)	6	0
Weighted average exercise price of options (in usd per share)	$ 30.75
Stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive securities (in shares)	0	4