Investment securities (Details Textual) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Available-For-Sale Securities [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Securities Pledged As Collateral, At Fair Value	$ 296.8	$ 152.3
Held-To-Maturity Securities [Member]
Schedule of Investments [Line Items]
Pledged Assets Separately Reported, Securities Pledged As Collateral, At Fair Value	$ 13.0	$ 19.4

The sum of the fair values, as of the date of each statement of financial position presented, of securities that are restricted as collateral for the payment of related debt obligations, primarily secured borrowings and repurchase agreements, and that are reclassified and separately reported in the statement of financial position because the transferee has the right by contract or custom to sell or re-pledge them.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 30

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6467456&loc=d3e113888-111728

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