Lease Commitments - Assets and Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Assets
Operating Lease Right-of-Use Asset	$ 560.5	$ 491.6
Liabilities
Operating Lease Liability	$ 700.6	$ 603.1
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssets	us-gaap:OtherAssets
Operating Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilities	us-gaap:OtherLiabilities