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Goodwill and Other Intangible Assets - Additional Information (Detail)
$ in Millions
12 Months Ended
Dec. 31, 2017
USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]  
2018 $ 20.1
2019 20.0
2020 19.9
2021 19.9
2022 19.7
Thereafter $ 158.8
Weighted average estimated remaining amortization period 13 years 8 months 18 days