Loans and leases and the allowance for credit losses (Details) (Textuals) (USD $)	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Loans and leases and allowance for credit losses (Details) (Textuals) [Abstract]
Loan delinquent period	90 days or more
Interest income on loans acquired	$ 69,000	$ 42,000	$ 110,000	$ 86,000
Delinquency period for loan-by-loan evaluation of collectability on residential real estate loans and home equity loans and lines of credit	more than 150 days
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value	753,000,000		753,000,000		97,000,000
Purchased impaired loans as a percentage of total assets			Less than 1% of companys assets		Less than .2% of companys assets
Interest income earned on purchased impaired loans	$ 5,000,000	$ 1,000,000	$ 7,000,000	$ 2,000,000

Certain loans acquired in transfer not accounted for as debt securities acquired impaired interest income recognized

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- Definition

Delinquency period for loan level collectability analysis consumer mortgage.

+ Details

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- Definition

Interest and fee income on loans acquired.

+ Details

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- Definition

Loan delinquent period.

+ Details

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- Definition

Loans acquired in transfer impaired as a percentage of total assets.

+ Details

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- Definition

Loans and leases and the allowance for credit losses.

+ Details

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- Definition

For loans not accounted for as debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable, the amount at which that asset (or liability) could be bought (or incurred) or sold (or settled) in a current transaction between willing parties, that is, other than in a forced or liquidation sale at the date of acquisition.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Statement of Position (SOP)
-Number 03-3
-Paragraph 16
-Subparagraph a(3)

+ Details

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