Quarterly report pursuant to Section 13 or 15(d)

Earnings Per Share - Additional Information (Detail)

v3.8.0.1
Earnings Per Share - Additional Information (Detail) - $ / shares
shares in Millions
3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]    
Equity grants with anti-dilutive effect 1.3 5.3
Convertible Senior Notes Due 2019 [Member]    
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]    
Convertible notes initial conversion price $ 86.28 $ 86.28
Convertible Senior Notes Due 2024 [Member]    
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]    
Convertible notes initial conversion price $ 124.96 $ 124.96