Mortgage Servicing Rights and Mortgage Servicing Activity (Details Textual) (USD $)	3 Months Ended	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2012	Jun. 30, 2011	Mar. 31, 2011	Jun. 30, 2012 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 3 [Member]		Dec. 31, 2011 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 3 [Member]		Jun. 30, 2011 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 3 [Member]
Servicing Assets at Fair Value [Line Items]
Servicing Asset at Amortized Value, Fair Value	$ 17,913,000	$ 17,913,000		$ 20,766,000	$ 17,913,000	[1]	$ 17,749,000	[2]	$ 20,766,000	[3]
Proceeds from Sale of Mortgage Loans Held-for-sale		414,385,000	214,996,000
Unpaid principal balances from sale of residential mortgage loans		410.2	211.6
Recognized pretax gains		4,200,000	3,400,000
Related mortgage servicing rights from loans sold and receives servicing fees	394,300,000	394,300,000	185,900,000
Principal amount of loans serviced	2,400,000,000	2,400,000,000	2,200,000,000
Loan servicing fees		$ 2,800,000	$ 2,700,000
Minimum percentage adverse change in prepayment speed	10.00%
Maximum percentage adverse change in prepayment speed	25.00%
Percentage of variation in prepayment speed	10.00%	10.00%

[1] Mortgage servicing rights with a recorded investment of $21.3 million were reduced by a specific valuation allowance totaling $3.5 million to a reported carrying value of $17.8 million resulting in recognition of $1.3 million in expense included in loans sales and servicing income in the quarter ended June 30, 2012.

[2] Mortgage servicing rights with a recorded investment of $21.2 million were reduced by a specific valuation allowance totaling $3.5 million to a reported carrying value of $17.6 million resulting in the recognition of an impairment charge of $3.5 million in the year ended December 31, 2011.

[3] Recorded at carrying value of $20.7 million as of June 30, 2011.