Goodwill and Intangible Assets - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Amortization expense	$ 17.8	$ 2.5
Estimated amortization expense, remainder of 2019	52.9
Estimated amortization expense, year 2020	70.7
Estimated amortization expense, year 2021	70.7
Estimated amortization expense, year 2022	70.7
Estimated amortization expense, year 2023	70.7
Estimated amortization expense, thereafter	$ 947.5