Derivatives and Hedging Activities (Details Textual) (USD $) In Millions, unless otherwise specified	3 Months Ended
Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Term of Written Loan Commitments	60 days
Remaining Term on Swap Participation Agreements, Min	1 year
Remaining Term on Swap Participation Agreements, Max	7 years
Derivative Instruments, Maximum Exposure	$ 2.9
Collateral posted against derivative liabilities	$ 103.0	$ 107.0	$ 113.8

The aggregate fair value of assets that are already posted, at the end of the reporting period, as collateral for derivative instruments with credit-risk-related contingent features.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4H

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5624258-113959

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 44D

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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_CollateralAlreadyPostedAggregateFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant