Fair Value Measurement (Recurring and Nonrecurring Table) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012		Sep. 30, 2012
Recurring Fair Value Measurements
Available-for-sale	$ 3,256,259		$ 2,920,971		$ 2,911,993
Residential loans held for sale	17,813		23,683		17,540
Derivative Asset, Fair Value, Gross Asset	53,839		63,231		70,270
Total Assets, Fair Value Disclosure, Recurring	3,327,911		3,007,885		2,999,803
Derivative Liability, Fair Value, Gross Liability	65,506		77,968		87,161
True Up Liability	11,457		12,259		12,642
Total liabilities at fair value on a recurring basis	76,963	[1]	90,227	[1]	99,803
Nonrecurring Fair Value Measurements [Abstract]
Fair Value of Mortgage Servicing Rights	22,616	[2]	18,833	[2]	17,294
Impaired and Non Accrual Loans Fair Value Disclosure	48,129	[3]	54,491	[3]	44,010
Other Real Estate, Non Covered	13,413	[4]	7,540	[4]	6,333
Other Real Estate Covered by Loss Share	8,475	[5]	12,631	[5]	14,695
Nonrecurring Fair Value	92,633		93,495		82,332
Level 1
Recurring Fair Value Measurements
Available-for-sale	3,096		3,241		3,245
Residential loans held for sale	0		0		0
Derivative Asset, Fair Value, Gross Asset	0		0		0
Total Assets, Fair Value Disclosure, Recurring	3,096		3,241		3,245
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
Recurring Fair Value Measurements
Available-for-sale	2,930,401		2,868,069		2,861,244
Residential loans held for sale	17,813		23,683		17,540
Derivative Asset, Fair Value, Gross Asset	53,839		63,231		70,270
Total Assets, Fair Value Disclosure, Recurring	3,002,053		2,954,983		2,949,054
Derivative Liability, Fair Value, Gross Liability	65,506		77,968		87,161
True Up Liability	0		0		0
Total liabilities at fair value on a recurring basis	65,506	[1]	77,968	[1]	87,161
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
Recurring Fair Value Measurements
Available-for-sale	322,762		49,661		47,504
Residential loans held for sale	0		0		0
Derivative Asset, Fair Value, Gross Asset	0		0		0
Total Assets, Fair Value Disclosure, Recurring	322,762		49,661		47,504
Derivative Liability, Fair Value, Gross Liability	0		0		0
True Up Liability	11,457		12,259		12,642
Total liabilities at fair value on a recurring basis	11,457	[1]	12,259	[1]	12,642
Nonrecurring Fair Value Measurements [Abstract]
Fair Value of Mortgage Servicing Rights	22,616	[2]	18,833		17,294
Impaired and Non Accrual Loans Fair Value Disclosure	48,129		54,491		44,010
Other Real Estate, Non Covered	13,413	[4]	7,540	[4]	6,333
Other Real Estate Covered by Loss Share	8,475	[5]	12,631	[5]	14,695
Nonrecurring Fair Value	92,633		93,495		82,332
Equity Securities
Recurring Fair Value Measurements
Available-for-sale	6,377		3,241		3,245
Equity Securities | Level 1
Recurring Fair Value Measurements
Available-for-sale			3,241		3,245
Equity Securities | Level 2
Recurring Fair Value Measurements
Available-for-sale			0		0
Equity Securities | Level 3
Recurring Fair Value Measurements
Available-for-sale			0		0
Marketable equity securities
Recurring Fair Value Measurements
Available-for-sale	3,096
Marketable equity securities | Level 1
Recurring Fair Value Measurements
Available-for-sale	3,096
Marketable equity securities | Level 2
Recurring Fair Value Measurements
Available-for-sale	0
Marketable equity securities | Level 3
Recurring Fair Value Measurements
Available-for-sale	0
Other Security Investments
Recurring Fair Value Measurements
Available-for-sale	3,281
Other Security Investments | Level 1
Recurring Fair Value Measurements
Available-for-sale	0
Other Security Investments | Level 2
Recurring Fair Value Measurements
Available-for-sale	10
Other Security Investments | Level 3
Recurring Fair Value Measurements
Available-for-sale	3,271
US Government Agency Debentures
Recurring Fair Value Measurements
Available-for-sale					35,137
US Government Agency Debentures | Level 1
Recurring Fair Value Measurements
Available-for-sale					0
US Government Agency Debentures | Level 2
Recurring Fair Value Measurements
Available-for-sale					35,137
US Government Agency Debentures | Level 3
Recurring Fair Value Measurements
Available-for-sale					0
U.S. States and political subdivisions debt securities
Recurring Fair Value Measurements
Available-for-sale	272,224		268,204		258,418
U.S. States and political subdivisions debt securities | Level 1
Recurring Fair Value Measurements
Available-for-sale	0		0		0
U.S. States and political subdivisions debt securities | Level 2
Recurring Fair Value Measurements
Available-for-sale	272,224		268,204		258,418
U.S. States and political subdivisions debt securities | Level 3
Recurring Fair Value Measurements
Available-for-sale	0		0		0
Residential Mortgage Backed Securities Issued by US Government Sponsored Enterprises
Recurring Fair Value Measurements
Available-for-sale	999,375		1,107,063		1,277,831
Residential Mortgage Backed Securities Issued by US Government Sponsored Enterprises | Level 1
Recurring Fair Value Measurements
Available-for-sale	0		0		0
Residential Mortgage Backed Securities Issued by US Government Sponsored Enterprises | Level 2
Recurring Fair Value Measurements
Available-for-sale	999,375		1,107,063		1,277,831
Residential Mortgage Backed Securities Issued by US Government Sponsored Enterprises | Level 3
Recurring Fair Value Measurements
Available-for-sale	0		0		0
Commercial Mortgage Backed Securities Issued by US Government Sponsored Enterprises
Recurring Fair Value Measurements
Available-for-sale	55,932		52,036		15,667
Commercial Mortgage Backed Securities Issued by US Government Sponsored Enterprises | Level 1
Recurring Fair Value Measurements
Available-for-sale	0		0		0
Commercial Mortgage Backed Securities Issued by US Government Sponsored Enterprises | Level 2
Recurring Fair Value Measurements
Available-for-sale	55,932		52,036		15,667
Commercial Mortgage Backed Securities Issued by US Government Sponsored Enterprises | Level 3
Recurring Fair Value Measurements
Available-for-sale	0		0		0
Residential Collateralized Mortgage-Backed Securities Issued by US Government Sponsored Enterprises
Recurring Fair Value Measurements
Available-for-sale	1,505,706		1,329,421		1,205,525
Residential Collateralized Mortgage-Backed Securities Issued by US Government Sponsored Enterprises | Level 1
Recurring Fair Value Measurements
Available-for-sale	0		0		0
Residential Collateralized Mortgage-Backed Securities Issued by US Government Sponsored Enterprises | Level 2
Recurring Fair Value Measurements
Available-for-sale	1,505,706		1,329,421		1,205,525
Residential Collateralized Mortgage-Backed Securities Issued by US Government Sponsored Enterprises | Level 3
Recurring Fair Value Measurements
Available-for-sale	0		0		0
Residential Collateralized Mortgage-Backed Securities Issued by Non-US Government Agency
Recurring Fair Value Measurements
Available-for-sale	9		11		12
Residential Collateralized Mortgage-Backed Securities Issued by Non-US Government Agency | Level 1
Recurring Fair Value Measurements
Available-for-sale	0		0		0
Residential Collateralized Mortgage-Backed Securities Issued by Non-US Government Agency | Level 2
Recurring Fair Value Measurements
Available-for-sale	0		2		1
Residential Collateralized Mortgage-Backed Securities Issued by Non-US Government Agency | Level 3
Recurring Fair Value Measurements
Available-for-sale	9		9		11
Commercial Collateralized Mortgage Backed Securities Issued by US Government Sponsored Enterprises
Recurring Fair Value Measurements
Available-for-sale	97,154		111,343		68,665
Commercial Collateralized Mortgage Backed Securities Issued by US Government Sponsored Enterprises | Level 1
Recurring Fair Value Measurements
Available-for-sale	0		0		0
Commercial Collateralized Mortgage Backed Securities Issued by US Government Sponsored Enterprises | Level 2
Recurring Fair Value Measurements
Available-for-sale	97,154		111,343		68,665
Commercial Collateralized Mortgage Backed Securities Issued by US Government Sponsored Enterprises | Level 3
Recurring Fair Value Measurements
Available-for-sale	0		0		0
Corporate debt securities
Recurring Fair Value Measurements
Available-for-sale	50,850		49,652		47,493
Corporate debt securities | Level 1
Recurring Fair Value Measurements
Available-for-sale	0		0		0
Corporate debt securities | Level 2
Recurring Fair Value Measurements
Available-for-sale	0		0		0
Corporate debt securities | Level 3
Recurring Fair Value Measurements
Available-for-sale	50,850		49,652		47,493
Collateralized Loan Obligations
Recurring Fair Value Measurements
Available-for-sale	268,632
Collateralized Loan Obligations | Level 1
Recurring Fair Value Measurements
Available-for-sale	0
Collateralized Loan Obligations | Level 2
Recurring Fair Value Measurements
Available-for-sale	0
Collateralized Loan Obligations | Level 3
Recurring Fair Value Measurements
Available-for-sale	268,632
Not Designated as Hedging Instrument
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	53,839	[6]	63,231	[6]	70,270	[6]
Derivative Liability, Fair Value, Gross Liability	52,217	[7]	58,888	[7]	65,090	[7]
Interest Rate Swap | Designated as Hedging Instrument
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	0	[6]	0	[6]	0	[6]
Derivative Liability, Fair Value, Gross Liability	13,289	[7]	19,080	[7]	22,071	[7]
Interest Rate Swap | Designated as Hedging Instrument | Level 1
Recurring Fair Value Measurements
Derivative Liability, Fair Value, Gross Liability	0		0		0
Interest Rate Swap | Designated as Hedging Instrument | Level 2
Recurring Fair Value Measurements
Derivative Liability, Fair Value, Gross Liability	13,289		19,080		22,071
Interest Rate Swap | Designated as Hedging Instrument | Level 3
Recurring Fair Value Measurements
Derivative Liability, Fair Value, Gross Liability	0		0		0
Interest Rate Swap | Not Designated as Hedging Instrument
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	51,044	[6]	58,769	[6]	62,796	[6]
Derivative Liability, Fair Value, Gross Liability	51,044	[7]	58,769	[7]	62,796	[7]
Interest Rate Swap | Not Designated as Hedging Instrument | Level 1
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 | Not Designated as Hedging Instrument | Level 2
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	51,044		58,769		62,796
Derivative Liability, Fair Value, Gross Liability	51,044		58,769		62,796
Interest Rate Swap | Not Designated as Hedging Instrument | Level 3
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 | Not Designated as Hedging Instrument
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	2,729	[6]	4,400	[6]	7,394	[6]
Derivative Liability, Fair Value, Gross Liability	0	[7]	0	[7]	0	[7]
Mortgage Loan Commitments | Not Designated as Hedging Instrument | Level 1
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	0		0		0
Mortgage Loan Commitments | Not Designated as Hedging Instrument | Level 2
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	2,729		4,400		7,394
Mortgage Loan Commitments | Not Designated as Hedging Instrument | Level 3
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	0		0		0
Forward sales contracts | Not Designated as Hedging Instrument
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	0	[6]	0	[6]	0	[6]
Derivative Liability, Fair Value, Gross Liability	1,081	[7]	62	[7]	2,223	[7]
Forward sales contracts | Not Designated as Hedging Instrument | Level 1
Recurring Fair Value Measurements
Derivative Liability, Fair Value, Gross Liability	0		0		0
Forward sales contracts | Not Designated as Hedging Instrument | Level 2
Recurring Fair Value Measurements
Derivative Liability, Fair Value, Gross Liability	1,081		62		2,223
Forward sales contracts | Not Designated as Hedging Instrument | Level 3
Recurring Fair Value Measurements
Derivative Liability, Fair Value, Gross Liability	0		0		0
Foreign Exchange | Not Designated as Hedging Instrument
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	66	[6]	62	[6]	80	[6]
Derivative Liability, Fair Value, Gross Liability	92	[7]	57	[7]	71	[7]
Foreign Exchange | Not Designated as Hedging Instrument | Level 1
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	0		0		0
Derivative Liability, Fair Value, Gross Liability	0		0		0
Foreign Exchange | Not Designated as Hedging Instrument | Level 2
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	66		62		80
Derivative Liability, Fair Value, Gross Liability	92		57		71
Foreign Exchange | Not Designated as Hedging Instrument | Level 3
Recurring Fair Value Measurements
Derivative Asset, Fair Value, Gross Asset	0		0		0
Derivative Liability, Fair Value, Gross Liability	0		0		0
Other Contract | Not Designated as Hedging Instrument
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]

[1] (a) - There were no transfers between levels 1 and 2 of the fair value hierarchy during the three months ended September 30, 2013.

[2] (b) - MSRs with a recorded investment of $22.9 million were reduced by a specific valuation allowance totaling $0.6 million to a reported carrying value of $22.4 million resulting in recognition of $0.1 million in recoveries included in loans sales and servicing income in the three months ended September 30, 2013.

[3] (c) - Collateral dependent impaired loans with a recorded investment of $51.3 million were reduced by specific valuation allowance allocations totaling $3.1 million to a reported net carrying value of $48.1 million.

[4] (d) - Amounts do not include assets held at cost at September 30, 2013. During the three months ended September 30, 2013, the re-measurement of foreclosed assets at fair value subsequent to initial recognition resulted in losses of $0.3 million included in noninterest expense.

[5] (e) - Amounts do not include assets held at cost at September 30, 2013. During the three months ended September 30, 2013, the re-measurement of covered foreclosed assets at fair value subsequent to initial recognition resulted in losses $0.2 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