Restrictions On Cash Due From Banks (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Restricted Cash and Investments [Abstract]
Reserve balance	$ 37.8	$ 33.3

Cash and investments whose use in whole or in part is restricted for the long-term, generally by contractual agreements or regulatory requirements. For use in an unclassified balance sheet.

No definition available.

Name:	us-gaap_RestrictedCashAndInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant