Business Segment Information (Detail Textuals)	12 Months Ended
Dec. 31, 2017 Segment
Business Segment Information
Number of reportable segments	2
Percentage of assets related to international operations	less than 10 percent

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

No definition available.

Name:	us-gaap_NumberOfReportableSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration