Allowance for Credit Losses - Troubled Debt Restructurings (Details) (USD $)	3 Months Ended
Mar. 31, 2013 Loans	Mar. 31, 2012
Financing Receivable, Modifications [Line Items]
Reserves specific to modified loans	$ 605,000
Defaults on troubled debt restructurings	0
Increase in allowance related to TDR's with subsequent defaults	6,000	427,000
Loans and Leases Receivable, Impaired, Commitment to Lend	$ 550,000

Reflects the unfunded portion of contractual agreements to lend funds to borrowers for loans whose terms have been modified by troubled debt restructuring.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 40

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6951948&loc=d3e18794-111554

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 15

-Paragraph 40

-Subparagraph b.

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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