Loans and reserve for credit losses Loans and reserve for credit losses (Schedule of Financing Receivables, Modified and Recorded as TDRs) ( (Details) $ in Thousands	3 Months Ended
Mar. 31, 2017 USD ($) loan	Mar. 31, 2016 USD ($) loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans \| loan	0	1
TDR outstanding recorded investment \| $	$ 0	$ 22
Commercial real estate \| Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans \| loan	0	0
TDR outstanding recorded investment \| $	$ 0	$ 0
Construction \| Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans \| loan	0	0
TDR outstanding recorded investment \| $	$ 0	$ 0
Residential real estate \| Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans \| loan	0	0
TDR outstanding recorded investment \| $	$ 0	$ 0
Commercial and industrial \| Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans \| loan	0	1
TDR outstanding recorded investment \| $	$ 0	$ 22
Consumer \| Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans \| loan	0	0
TDR outstanding recorded investment \| $	$ 0	$ 0

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- Definition

Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953676-111524

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- Definition

The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=25495931&loc=d3e18845-111554

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Recorded Investment
-URI http://asc.fasb.org/extlink&oid=65880944

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