XML 96 R81.htm IDEA: XBRL DOCUMENT v3.8.0.1
Leases - Additional Information (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Leases [Abstract]      
Rent expense $ 48.9 $ 25.3 $ 37.6