Mortgage Banking Activities, Mortgage Servicing Rights (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Summary of Mortgage Servicing Rights [Abstract]
Number of residential mortgage loans serviced			96,578	96,152	96,443
Outstanding principal balance of residential mortgage loans serviced for others	$ 11,283,442	$ 10,991,572	$ 11,283,442	$ 10,991,572	$ 11,194,582
Weighted average interest rate (in hundredths)			5.36%	5.63%	5.44%
Remaining term (in months)			291 M	296 M	292 M
Servicing Asset at Fair Value, Amount [Roll Forward]
Beginning balance	120,345	119,066	115,723	73,824	73,824
Additions, net	5,798	5,161	10,767	42,254
Change in fair value due to loan runoff	(3,458)	(5,827)	(6,934)	(11,610)
Gain on purchase of mortgage servicing rights				11,832
Change in fair value due to market changes	(13,493)	(19,458)	(10,364)	(17,358)
Ending balance	109,192	98,942	109,192	98,942	115,723
Servicing Assets at Fair Value, Assumptions Used to Estimate Fair Value [Abstract]
Discount rate - risk-free rate plus a market premium (in hundredths)			10.36%	10.38%	10.36%
Prepayment rate - estimated based upon loan interest rate, original term and loan type, minimum (in hundredths)			10.26%	8.30%	6.53%
Prepayment rate - estimated based upon loan interest rate, original term and loan type, maximum (in hundredths)			38.37%	34.50%	23.03%
Loan servicing costs - annually per loan based upon loan type, minimum (in dollars per loan)			55	35	35
Loan servicing costs - annually per loan based upon loan type, maximum (in dollars per loan)			105	60	60
Escrow earnings rate - indexed to rates paid on deposit accounts with comparable average life (in hundredths)			2.02%	1.34%	2.21%
Purchased [Member]
Servicing Asset at Fair Value, Amount [Roll Forward]
Beginning balance	38,343	51,919	37,900	7,828	7,828
Additions, net	0	0	0	31,892
Change in fair value due to loan runoff	(1,218)	(1,313)	(2,551)	(2,641)
Gain on purchase of mortgage servicing rights				11,832
Change in fair value due to market changes	(4,259)	(13,160)	(2,483)	(11,465)
Ending balance	32,866	37,446	32,866	37,446
Originated [Member]
Servicing Asset at Fair Value, Amount [Roll Forward]
Beginning balance	82,002	67,147	77,823	65,996	65,996
Additions, net	5,798	5,161	10,767	10,362
Change in fair value due to loan runoff	(2,240)	(4,514)	(4,383)	(8,969)
Gain on purchase of mortgage servicing rights				0
Change in fair value due to market changes	(9,234)	(6,298)	(7,881)	(5,893)
Ending balance	$ 76,326	$ 61,496	$ 76,326	$ 61,496

Indicates the number of mortgage loans being serviced.

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Dollar amount of principal outstanding on mortgage loans being serviced.

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The weighted average remaining term of the mortgage loans being serviced.

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The escrow earning rate used to estimate the fair value of servicing assets, based on rates paid on deposit accounts.

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The maximum cost to service a loan for the period used as a variable in estimating fair value.

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The minimum cost to service a loan for the period used as a variable in estimating fair value.

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The maximum estimated speed of prepayments of principal on financial assets which may be one of the factors applied in estimating the fair value of servicing assets.

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The minimum estimated speed of prepayments of principal on financial assets which may be one of the factors applied in estimating the fair value of servicing assets.

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The net increase or decrease in fair value as a result of changes in the assumptions or model used to calculate the fair value of servicing assets.

+ References

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The stated interest rate on the mortgage loan receivable or the weighted average interest rate on a group of loans.

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-Name Accounting Standards Codification
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-SubTopic 310
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-Subparagraph (SX 210.12-29)
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The value of new servicing assets, subsequently measured at fair value, acquired or created during the current period through purchases or from transfers of financial assets.

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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

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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The net increase or decrease in fair value as a result of changes in the inputs used to calculate the fair value of servicing assets.

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Other net Increase or Decrease in the balance in servicing assets subsequently measured at fair value. This element is for changes other than additions, disposals, changes in fair value resulting from changes in valuation inputs or changes in assumptions, or other changes in fair value.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-Paragraph 17
-Subparagraph f(1)(e)
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The discount rate used to estimate the fair value of servicing assets and servicing liabilities.

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