Retirement Plans - Additional Information (Details) $ in Millions	12 Months Ended
Dec. 31, 2017 USD ($)
Retirement Benefits [Abstract]
Employer matching contributions	$ 1.1

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