Employee Benefit Plans (Details)	12 Months Ended
Dec. 31, 2017 USD ($) plan	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Retirement Benefits [Abstract]
Number of voluntary defined contribution plans \| plan	2
Contributions to the 401(k) plans \| $	$ 0	$ 0	$ 0

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