Schedule of Components of Lease Expense (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Finance lease cost
Amortization of right-of-use assets	$ 0.2	$ 0.7
Interest on lease liabilities		0.1
Operating lease cost	3.9	12.2
Short-term lease cost	0.2	0.5
Variable lease cost	0.5	1.4
Total lease cost	$ 4.8	$ 14.9