Fair Value Measurement (Recurring and Nonrecurring Table) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012		Mar. 31, 2012
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	$ 3,243,835		$ 2,920,971		$ 3,491,647
Residential loans held for sale	14,459		23,683		42,447
Derivative Asset, Fair Value, Gross Asset	58,563		63,169		60,115
Total Assets, Fair Value Disclosure, Recurring	3,316,857		3,007,823		3,594,209
Derivative Liability, Fair Value, Gross Liability	71,933		77,906		80,174
True Up Liability	12,783		12,259		11,725
Total liabilities at fair value on a recurring basis	84,716	[1]	90,165	[1]	91,899
Nonrecurring Fair Value Measurements [Abstract]
Fair Value of Mortgage Servicing Rights	20,223	[2]	18,833	[2]	18,869
Impaired and Non Accrual Loans Fair Value Disclosure	54,382	[3]	54,491	[3]	60,018
Other Real Estate, Non Covered	5,532	[4]	7,540	[4]	4,768
Other Real Estate Covered by Loss Share	16,504	[5]	12,631	[5]	47,765
Nonrecurring Fair Value	96,641		93,495		131,420
Level 1 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	3,212		3,241		3,308
Residential loans held for sale	0		0		0
Derivative Asset, Fair Value, Gross Asset	0		0		0
Total Assets, Fair Value Disclosure, Recurring	3,212		3,241		3,308
Derivative Liability, Fair Value, Gross Liability	0		0		0
True Up Liability	0		0		0
Total liabilities at fair value on a recurring basis	0	[1]	0	[1]	0
Nonrecurring Fair Value Measurements [Abstract]
Fair Value of Mortgage Servicing Rights	0	[2]	0	[2]	0
Impaired and Non Accrual Loans Fair Value Disclosure	0	[3]	0	[3]	0
Other Real Estate, Non Covered	0	[4]	0	[4]	0
Other Real Estate Covered by Loss Share	0	[5]	0	[5]	0
Nonrecurring Fair Value	0		0		0
Level 2 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	3,189,389		2,868,069		3,399,852
Residential loans held for sale	14,459		23,683		42,447
Derivative Asset, Fair Value, Gross Asset	58,563		63,169		60,115
Total Assets, Fair Value Disclosure, Recurring	3,262,411		2,954,921		3,502,414
Derivative Liability, Fair Value, Gross Liability	71,933		77,906		80,174
True Up Liability	0		0		0
Total liabilities at fair value on a recurring basis	71,933	[1]	77,906	[1]	80,174
Nonrecurring Fair Value Measurements [Abstract]
Fair Value of Mortgage Servicing Rights	0	[2]	0	[2]	0
Impaired and Non Accrual Loans Fair Value Disclosure	0	[3]	0	[3]	0
Other Real Estate, Non Covered	0	[4]	0	[4]	0
Other Real Estate Covered by Loss Share	0	[5]	0	[5]	0
Nonrecurring Fair Value	0		0		0
Level 3 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	51,234		49,661		88,487
Residential loans held for sale	0		0		0
Derivative Asset, Fair Value, Gross Asset	0		0		0
Total Assets, Fair Value Disclosure, Recurring	51,234		49,661		88,487
Derivative Liability, Fair Value, Gross Liability	0		0		0
True Up Liability	12,783		12,259		11,725
Total liabilities at fair value on a recurring basis	12,783	[1]	12,259	[1]	11,725
Nonrecurring Fair Value Measurements [Abstract]
Fair Value of Mortgage Servicing Rights	20,223	[2]	18,833		18,869
Impaired and Non Accrual Loans Fair Value Disclosure	54,382		54,491		60,018
Other Real Estate, Non Covered	5,532	[4]	7,540	[4]	4,768
Other Real Estate Covered by Loss Share	16,504	[5]	12,631	[5]	47,765
Nonrecurring Fair Value	96,641		93,495		131,420
Marketable equity securities [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	3,212		3,241		3,308
Marketable equity securities [Member] | Level 1 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	3,212		3,241		3,308
Marketable equity securities [Member] | Level 2 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	0		0		0
Marketable equity securities [Member] | Level 3 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	0		0		0
US Government Agency Debentures [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure					35,455
US Government Agency Debentures [Member] | Level 1 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure					0
US Government Agency Debentures [Member] | Level 2 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure					35,455
US Government Agency Debentures [Member] | Level 3 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure					0
U.S. States and political subdivisions [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	262,606		268,204		386,525
U.S. States and political subdivisions [Member] | Level 1 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	0		0		0
U.S. States and political subdivisions [Member] | Level 2 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	262,606		268,204		386,525
U.S. States and political subdivisions [Member] | Level 3 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	0		0		0
Residential Mortgage Backed Securities Issued by US Government Sponsored Enterprises [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	1,152,326		1,107,063		1,454,416
Residential Mortgage Backed Securities Issued by US Government Sponsored Enterprises [Member] | Level 1 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	0		0		0
Residential Mortgage Backed Securities Issued by US Government Sponsored Enterprises [Member] | Level 2 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	1,152,326		1,107,063		1,454,416
Residential Mortgage Backed Securities Issued by US Government Sponsored Enterprises [Member] | Level 3 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	0		0		0
Commercial Mortgage Backed Securities Issued by US Government Sponsored Enterprises [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	58,574		52,036		27,663
Commercial Mortgage Backed Securities Issued by US Government Sponsored Enterprises [Member] | Level 1 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	0		0		0
Commercial Mortgage Backed Securities Issued by US Government Sponsored Enterprises [Member] | Level 2 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	58,574		52,036		27,663
Commercial Mortgage Backed Securities Issued by US Government Sponsored Enterprises [Member] | Level 3 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	0		0		0
Residential Collateralized Mortgage-Backed Securities Issued by US Government Sponsored Enterprises [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	1,605,279		1,329,421		1,251,304
Residential Collateralized Mortgage-Backed Securities Issued by US Government Sponsored Enterprises [Member] | Level 1 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	0		0		0
Residential Collateralized Mortgage-Backed Securities Issued by US Government Sponsored Enterprises [Member] | Level 2 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	1,605,279		1,329,421		1,251,304
Residential Collateralized Mortgage-Backed Securities Issued by US Government Sponsored Enterprises [Member] | Level 3 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	0		0		0
Residential Collateralized Mortgage-Backed Securities Issued by Non-US Government Agency [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	11		11		41,832
Residential Collateralized Mortgage-Backed Securities Issued by Non-US Government Agency [Member] | Level 1 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	0		0		0
Residential Collateralized Mortgage-Backed Securities Issued by Non-US Government Agency [Member] | Level 2 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	2		2		2
Residential Collateralized Mortgage-Backed Securities Issued by Non-US Government Agency [Member] | Level 3 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	9		9		41,830
Commercial Collateralized Mortgage Backed Securities Issued by US Government Sponsored Enterprises [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	110,602		111,343		147,355
Commercial Collateralized Mortgage Backed Securities Issued by US Government Sponsored Enterprises [Member] | Level 1 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	0		0		0
Commercial Collateralized Mortgage Backed Securities Issued by US Government Sponsored Enterprises [Member] | Level 2 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	110,602		111,343		147,355
Commercial Collateralized Mortgage Backed Securities Issued by US Government Sponsored Enterprises [Member] | Level 3 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	0		0		0
Corporate debt securities [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	51,225		49,652		143,789
Corporate debt securities [Member] | Level 1 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	0		0		0
Corporate debt securities [Member] | Level 2 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	0		0		97,132
Corporate debt securities [Member] | Level 3 [Member]
Recurring Fair Value Measurements
Available-for-sale Securities, Fair Value Disclosure	51,225		49,652		46,657
Not Designated as Hedging Instrument [Member]
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	58,563	[6]	63,169	[6]	60,115	[6]
Derivative Liability, Fair Value, Gross Liability	54,686	[7]	58,826	[7]	56,388	[7]
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	0	[6]	0	[6]	0	[6]
Derivative Liability, Fair Value, Gross Liability	17,247	[7]	19,080	[7]	23,786	[7]
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Level 1 [Member]
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	0		0		0
Derivative Liability, Fair Value, Gross Liability	0		0		0
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Level 2 [Member]
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	0		0		0
Derivative Liability, Fair Value, Gross Liability	17,247		19,080		23,786
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Level 3 [Member]
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	0		0		0
Derivative Liability, Fair Value, Gross Liability	0		0		0
Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member]
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	54,590	[6]	58,769	[6]	56,298	[6]
Derivative Liability, Fair Value, Gross Liability	54,590	[7]	58,769	[7]	56,298	[7]
Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member] | Level 1 [Member]
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	0		0		0
Derivative Liability, Fair Value, Gross Liability	0		0		0
Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member] | Level 2 [Member]
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	54,590		58,769		56,298
Derivative Liability, Fair Value, Gross Liability	54,590		58,769		56,298
Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member] | Level 3 [Member]
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	0		0		0
Derivative Liability, Fair Value, Gross Liability	0		0		0
Mortgage Loan Commitments [Member] | Not Designated as Hedging Instrument [Member]
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	4,152	[6]	4,400	[6]	3,268	[6]
Derivative Liability, Fair Value, Gross Liability	0	[7]	0	[7]	0	[7]
Mortgage Loan Commitments [Member] | Not Designated as Hedging Instrument [Member] | Level 1 [Member]
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	0		0		0
Mortgage Loan Commitments [Member] | Not Designated as Hedging Instrument [Member] | Level 2 [Member]
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	4,152		4,400		3,268
Mortgage Loan Commitments [Member] | Not Designated as Hedging Instrument [Member] | Level 3 [Member]
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	0		0		0
Forward Contracts [Member] | Not Designated as Hedging Instrument [Member]
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	(284)	[6]	(62)	[6]	446	[6]
Derivative Liability, Fair Value, Gross Liability	0	[7]	0	[7]	0	[7]
Forward Contracts [Member] | Not Designated as Hedging Instrument [Member] | Level 1 [Member]
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	0		0		0
Forward Contracts [Member] | Not Designated as Hedging Instrument [Member] | Level 2 [Member]
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	(284)		(62)		446
Forward Contracts [Member] | Not Designated as Hedging Instrument [Member] | Level 3 [Member]
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	0		0		0
Foreign Exchange [Member] | Not Designated as Hedging Instrument [Member]
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	105	[6]	62	[6]	103	[6]
Derivative Liability, Fair Value, Gross Liability	96	[7]	57	[7]	90	[7]
Foreign Exchange [Member] | Not Designated as Hedging Instrument [Member] | Level 1 [Member]
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	0		0		0
Derivative Liability, Fair Value, Gross Liability	0		0		0
Foreign Exchange [Member] | Not Designated as Hedging Instrument [Member] | Level 2 [Member]
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	105		62		103
Derivative Liability, Fair Value, Gross Liability	96		57		90
Foreign Exchange [Member] | Not Designated as Hedging Instrument [Member] | Level 3 [Member]
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	0		0		0
Derivative Liability, Fair Value, Gross Liability	0		0		0
Other Contract [Member] | Not Designated as Hedging Instrument [Member]
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	0	[6]	0	[6]	0	[6]
Derivative Liability, Fair Value, Gross Liability	0	[7]	0	[7]	0	[7]
Other Contract [Member] | Not Designated as Hedging Instrument [Member] | Level 1 [Member]
Recurring Fair Value Measurements
Derivative Liability, Fair Value, Gross Liability	0		0		0
Other Contract [Member] | Not Designated as Hedging Instrument [Member] | Level 2 [Member]
Recurring Fair Value Measurements
Derivative Liability, Fair Value, Gross Liability	0		0		0
Other Contract [Member] | Not Designated as Hedging Instrument [Member] | Level 3 [Member]
Recurring Fair Value Measurements
Derivative Liability, Fair Value, Gross Liability	$ 0		$ 0		$ 0

[1] (a) - There were no transfers between levels 1 and 2 of the fair value hierarchy during the three months ended March 31, 2013.

[2] (b) - MSRs with a recorded investment of $21.4 million were reduced by a specific valuation allowance totaling $1.2 million to a reported carrying value of $20.1 million resulting in recognition of $1.3 million in expense included in loans sales and servicing income in the three months ended March 31, 2013.

[3] (c) - Collateral dependent impaired loans with a recorded investment of $58.9 million were reduced by specific valuation allowance allocations totaling $4.5 million to a reported net carrying value of $54.4 million.

[4] (d) - Amounts do not include assets held at cost at March 31, 2013. During the three months ended March 31, 2013, the re-measurement of foreclosed assets at fair value subsequent to initial recognition resulted in losses of $0.2 million included in noninterest expense.

[5] (e) - Amounts do not include assets held at cost at March 31, 2013. During the three months ended March 31, 2013, the re-measurement of covered foreclosed assets at fair value subsequent to initial recognition resulted in losses $0.1 million included in noninterest expense.

[6] (a) Included in Other Assets on the Consolidated Balance Sheet

[7] (b) Included in Other Liabilities on the Consolidated Balance Sheet