Annual report pursuant to Section 13 and 15(d)

Share-Based Compensation - Restricted Unit Activity (Detail)

v3.6.0.2
Share-Based Compensation - Restricted Unit Activity (Detail) - USD ($)
$ in Millions
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Intrinsic value of options vested and expected to vest $ 9.0    
Restricted Stock Units [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Intrinsic value of options vested and expected to vest $ 0.9 $ 0.9 $ 0.4