Retirement Plan - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan name	401(k)
Defined contribution plan employer contribution description	The Company makes matching cash contributions subject to certain restrictions, structured as a 100% match on the first 1% contributed by the employee and a 50% match on the next 5% contributed by the employee.
Defined Contribution Plan, Sponsor Location [Extensible List]	country:US
Defined Contribution Plan, Tax Status [Extensible List]	us-gaap:QualifiedPlanMember
Selling, General and Administrative Expenses and Operating Expenses [Member]
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, employer- matching contributions	$ 7.6	$ 7.9	$ 8.5
First 1% [Member]
Defined Contribution Plan Disclosure [Line Items]
Employer matching percentage	100.00%
Percentage of gross pay matched	1.00%
Second 5% [Member]
Defined Contribution Plan Disclosure [Line Items]
Employer matching percentage	50.00%
Percentage of gross pay matched	5.00%