Leases - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Lessee Lease Description [Line Items]
Operating lease, liability	$ 86.1	$ 86.1
Operating lease, right-of-use asset	85.7	85.7		$ 0.0
Rent expense	$ 6.1	$ 18.7
ASU 2016-02
Lessee Lease Description [Line Items]
Operating lease, liability			$ 101.6
Operating lease, right-of-use asset			$ 100.8