Business segment information (Details 1) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Reconciliation of Net other income:
Net other income - business segment	$ 26,828	$ 36,103	$ 2,262
Reversal of provision for losses on off-balance sheet credit risk	4,046	4,448	13,926
Recoveries, net of impairment of assets	0	(57)	233
Gain on sale of premises and equipment	5,626	0	0
Net other income consolidated financial statements	$ 36,500	$ 40,494	$ 16,421

The difference between the sale price or salvage price and the book value of a property, plant, and equipment asset that was sold or retired during the reporting period. This element refers to the gain (loss).

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 28

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585

Name:	us-gaap_GainLossOnSaleOfPropertyPlantEquipment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration