Commitments and Contingencies - Capital Leases and Operating Leases Narrative (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Loss Contingencies [Line Items]
Remaining term on operating lease	8 years
Rent expense	$ 41.6	$ 41.2	$ 39.6
Minimum
Loss Contingencies [Line Items]
Capital leases term of contract	1 year
Maximum
Loss Contingencies [Line Items]
Capital leases term of contract	15 years