Annual report pursuant to Section 13 and 15(d)

Intangible Assets - Narrative (Detail)

v3.8.0.1
Intangible Assets - Narrative (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]      
Amortization expense for intangibles $ 12.3 $ 10.8 $ 11.3