Operating Revenue (Details)	6 Months Ended
Jun. 30, 2018 division Segment
Revenue from Contract with Customer [Abstract]
Number of company divisions \| division	85
Number of reportable segments \| Segment	7

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