Employee Benefit Plans (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Retirement Benefits [Abstract]
Maximum Annual Contributions Per Employee, Percent	80.00%
Discretionary matching contributions	$ 0.2	$ 0.3

Maximum percentage of employee gross pay the employee may contribute to a defined contribution plan.

No definition available.

Name:	us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration