Allowance for Loan Losses and Credit Quality (Consumer Mortgage Loans Secured by Residential Real Estate in Process of Foreclosure) (Details) $ in Thousands	6 Months Ended	12 Months Ended
Jun. 30, 2018 USD ($) loan	Dec. 31, 2017 USD ($) loan
Receivables [Abstract]
Number of loans \| loan	1	1
Recorded Investment \| $	$ 77	$ 77

Recorded investment of consumer mortgage loan receivables secured by residential real estate properties for which formal foreclosure proceedings are in process.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 35
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL49126937-111524

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