Annual report pursuant to Section 13 and 15(d)

Subsequent Events - Additional Information (Detail)

v3.8.0.1
Subsequent Events - Additional Information (Detail) - USD ($)
$ in Millions
1 Months Ended
Jan. 31, 2018
Dec. 31, 2017
Feb. 21, 2017
Subsequent Event [Line Items]      
Share repurchase program authorized amount $ 1,500.0 $ 1,500.0 $ 1,500.0
Subsequent Event [Member] | Open market purchases [Member]      
Subsequent Event [Line Items]      
Repurchase of common stock, shares 4,200    
Repurchase of common stock, value $ 0.3