Allowance for Credit Losses Troubled Debt Restructuring (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013 loans	Dec. 31, 2012 loans	Mar. 31, 2012
Allowance for Credit Losses [Abstract]
Financing Receivable, Modifications, Number of Contracts	32	26
Financing Receivable, Modifications, Subsequent Default, Recorded Investment During Year	$ 0		$ 1,420

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

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=7512638&loc=SL6953676-111524

Name:	us-gaap_FinancingReceivableModificationsNumberOfContracts1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant