Long-Term Debt - 2017 Credit Facility - Additional Information (Detail) - 2017 Credit Facility - USD ($) $ in Millions			1 Months Ended	12 Months Ended
	May 01, 2019	Nov. 30, 2017	Dec. 31, 2018	Dec. 31, 2018
Debt Instrument [Line Items]
Agreement date		Nov. 30, 2017
Additional borrowing capacity		$ 100.0
First lien net leverage ratio		4.00%
Percentage of repricing fee		1.00%
Certain customary events of default, number of business days to default in the payment of interest on borrowings				3 days
Certain customary events of default, number of days default continue for compliance with other agreement				30 days
Certain customary events of default, number of days default continue for financial statement delivery obligations				10 days
Certain customary events of default, indebtedness aggregate amount				$ 15.0
Certain customary events of default, failure in payment of final judgments aggregate amount				$ 15.0
Certain customary events of default, failure in payment of final judgments aggregate amount period				30 days
Subsequent Events
Debt Instrument [Line Items]
Percentage of fee equal to amount of outstanding loan	0.10%
Total fee amount	$ 0.2
Eurodollar Rate
Debt Instrument [Line Items]
Variable interest rate basis spread on debt		2.75%
Base Rate Margin
Debt Instrument [Line Items]
Variable interest rate basis spread on debt		1.75%
Term Loan B Facility
Debt Instrument [Line Items]
Senior Secured debt		$ 300.0
Maturity date of revolving credit facility		Nov. 30, 2024
Interest rate on term loan		5.09%
Period considered for applicability of repricing fees		6 months
Prepayment to reduce loans outstanding			$ 50.0