Loans (Textual) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013 BaordOfDirectors Tenants Segment Loans	Dec. 31, 2012	Sep. 30, 2012
Loans (Textual) [Abstract]
Number of portfolio segment	2
Number of classes of loans	7
Number of tenants under lease of real estate	1
Number of members of the board of directors in loan committee	9
Minimum due period of loans consider in a nonperforming status	90 days
Total nonaccrual loans	$ 39.1	$ 47.5	$ 37.0
Difference between recorded investment and unpaid principal balance of loan	24.6	21.1	23.4
Confirmed losses (partial charge-offs)	21.2	17.3	19.8
Fair value of discount adjustment	3.4	3.8	3.6
Acquired impaired loans	7.6	9.1	9.4
Performing trouble debt restructuring under impaired loans	34.1	31.4	30.4
Financing receivable allowance for acquired loans	0.5	0.5	0.5
Number of minimum days for performing and nonperforming trouble debt restructuring	90 days
Commercial Loan Portfolio [Member]
Loans (Textual) [Abstract]
Minimum value of loan requires executive and senior officer approval	1.5
Consumer Portfolio Segment [Member]
Loans (Textual) [Abstract]
Original contractual terms	90 days
Minimum due period of loans consider in a nonperforming status	90 days
Commercial [Member]
Loans (Textual) [Abstract]
Minimum value of loan requires group loan authority approval	1.0
Maximum value of loan requires executive and senior officer approval	3.5
Real Estate Residential Loans [Member]
Loans (Textual) [Abstract]
Period for loan secured under real estate residential security	15 years
Loan-to-value ratio at the time of origination	80.00%
Land Development Loans [Member]
Loans (Textual) [Abstract]
Maximum period for payment of loan	12 months
Maximum [Member] | Commercial Loan Portfolio [Member]
Loans (Textual) [Abstract]
Maximum value of loan requires group loan authority approval	5.0
Other loans requiring director loan committee approval depending on risk rating and credit action required	5.0
Maximum [Member] | Real Estate Residential Loans [Member]
Loans (Textual) [Abstract]
Upper limit of number of family residential properties	4
Minimum [Member] | Commercial Loan Portfolio [Member]
Loans (Textual) [Abstract]
Minimum value of loan requires group loan authority approval	1.0
Maximum value of loans depending on risk rating and requires credit action from board of directors	10.0
Minimum [Member] | Commercial [Member]
Loans (Textual) [Abstract]
Minimum value of loans requiring only director loan committee approval	$ 5.0
Minimum [Member] | Real Estate Residential Loans [Member]
Loans (Textual) [Abstract]
Lower limit of number of family residential properties	1