Other Assets (Detail) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Other assets
Investments in affiliated companies (Note 5)	$ 130.0	$ 133.7
Right-of-use lease assets	66.4	71.2
Non-qualified employee benefit plan assets	9.9	12.7
Deposits	4.8	4.1
Notes receivable from affiliated companies	4.0	4.0
Deferred financing fees	1.6	1.9
Other	12.6	8.7
Total other assets	$ 229.3	$ 236.3