Time deposits (Narrative) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Time Deposits, Type [Line Items]
Time Deposits, $100,000 or More	$ 113,700,000us-gaap_TimeDeposits100000OrMore	$ 92,700,000us-gaap_TimeDeposits100000OrMore
Wholesale Brokered Time Deposits
Time Deposits, Type [Line Items]
Time Deposits	$ 0	$ 0

The aggregate amount of domestic and foreign time deposit liabilities (including certificates of deposits, individual retirement accounts and open accounts) in denominations of $100,000 or more.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 405

-Section 50

-Paragraph 1

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6479006&loc=d3e64164-112818

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Industry Guide

-Number 3

-Section V

-Paragraph A

-Subparagraph 4

Name:	us-gaap_TimeDeposits100000OrMore
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant