Federal Home Loan Bank Advances (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012
Federal Home Loan Bank, Advances, Activity for Year [Abstract]
Federal Home Loan Bank advances, Restructured advances	$ 292.5
Federal Home Loan Bank advances, Prepayment fees	22.4
Federal Home Loan Bank advances having varying call dates	35.0
Federal Home Loan Bank Advances, weighted average contractual interest rate	1.40%
Federal Home Loan Bank Advances, weighted average effective Interest rate	1.32%
Federal Home Loan Bank advances, Additional borrowings possible	$ 570.6

Amount of advances or credit lines available from the Federal Home Loan Bank (FHLB).

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

-Publisher FASB

-Name Accounting Standards Codification

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

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

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Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

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