Time deposits (Narrative) (Details) - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Time Deposits, Type [Line Items]
Time deposits	$ 32,500,000	$ 45,200,000
Wholesale Brokered Time Deposits
Time Deposits, Type [Line Items]
Wholesale brokered deposits	$ 0	$ 0

Amount of interest-bearing domestic third-party deposits placed by or through the assistance of a deposit broker, also known as brokered deposit liabilities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.12)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 12
-Article 9

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