Business Segments (Details) $ in Billions	9 Months Ended
Sep. 30, 2017 USD ($) branch business_line segment
Business segments
Reportable segments \| segment	4
Regional Bank
Business segments
Major business lines \| business_line	5
Consumer and Business Banking Division
Business segments
Number of full-service branches \| branch	349
Commercial Banking \| Regional Bank
Business segments
Commercial banking customer revenues \| $	$ 1

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