Employee Benefit Plan (Details) - USD ($) $ in Millions		12 Months Ended
Feb. 02, 2007	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Postemployment Benefits [Abstract]
Postemployment benefit, minimum attained age	21 years
Employer's discretionary matching contributions		$ 0.2	$ 0.2	$ 0.1

Amount of discretionary contributions made by an employer to a defined contribution plan.

No definition available.

Name:	us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration