Significant Accounting Policies, Self-Funded Health Insurance (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Self-Funded Health Insurance [Abstract]
Reserve for self-funded health insurance program	$ 648	$ 679

Carrying amount of accrued known and estimated losses incurred as of the balance sheet date for which no insurance coverage exists, and for which a claim has been made or is probable of being asserted, typically arising from workmen's compensation-type of incidents and personal injury to nonemployees from accidents on the entity's property that are expected to be paid within one year (or the normal operating cycle, if longer).

No definition available.

Name:	us-gaap_SelfInsuranceReserveCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant