Leases - Summary of Components of Lease Cost (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease cost	$ 79.0	$ 80.9
Finance lease cost:
Amortization of right-of-use assets	3.6	3.4
Interest on lease liabilities	0.6	0.5
Variable lease cost	16.9	21.1
Short-term lease cost	31.3	33.0
Total lease cost	$ 131.4	$ 138.9