Introduction and Basis of Presentation (Details)	Dec. 31, 2017 state office
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Minimum number of domestic branch offices \| office	345
States with domestic branch offices \| state	46

The number of states the entity operates in as of the balance sheet date.

No definition available.

Name:	us-gaap_NumberOfStatesInWhichEntityOperates
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant