Lease Commitments - Supplemental Cash Flow Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Cash paid for amounts included in the measurement of lease liabilities - operating cash flows	$ 107.9	$ 101.2
Supplemental non-cash information
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 164.8	$ 108.3