Fair Value Part 1 (Details) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2010	Dec. 31, 2009
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
U.S. Government agency obligations	$ 61,875	$ 122,035
Obligations of states and political subdivisions	207,781	159,637
Mortgage-backed securities	2,207,249	1,895,577
Securities available for sale	2,476,905	2,177,249
Loans held for sale	210,269	153,044
Mortgage servicing rights	43,659	51,151	41,972	50,513
Other assets - derivatives	3,061	(2,247)
Other liabilities - derivatives	5,471	(1,581)
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
U.S. Government agency obligations	0	0
Obligations of states and political subdivisions	0	0
Mortgage-backed securities	0	0
Securities available for sale	0	0
Loans held for sale	0	0
Mortgage servicing rights	0	0
Other assets - derivatives	459	(2,584)
Other liabilities - derivatives	658	1,562
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
U.S. Government agency obligations	61,875	122,035
Obligations of states and political subdivisions	207,781	159,637
Mortgage-backed securities	2,207,249	1,895,577
Securities available for sale	2,476,905	2,177,249
Loans held for sale	210,269	153,044
Mortgage servicing rights	0	0
Other assets - derivatives	1,073	0
Other liabilities - derivatives	4,813	(3,143)
Fair Value, Inputs, Level 3 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
U.S. Government agency obligations	0	0
Obligations of states and political subdivisions	0	0
Mortgage-backed securities	0	0
Securities available for sale	0	0
Loans held for sale	0	0
Mortgage servicing rights	43,659	51,151
Other assets - derivatives	1,529	337
Other liabilities - derivatives	$ 0	$ 0

For an unclassified balance sheet, this item represents investments in debt and equity securities which are categorized neither as held-to-maturity nor trading.

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Reference 9: http://www.xbrl.org/2003/role/presentationRef

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+ Details

- Definition

Fair values as of the balance sheet date of all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements.

+ References+ Details

- Definition

The aggregate carrying amount of loans receivable that will be sold to other entities. Includes mortgage and all other loans (collectively, loans) not classified as held for investment. Such loans are stated at the lower of cost or market, or elected fair value. Mortgage loans exclude mortgage-backed securities which are considered a debt security (other loan).

+ References

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

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+ Details

- Definition

Fair value as of the balance sheet date of an asset representing net future revenues from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

+ References+ Details