Premises and Equipment (Schedule of Premises and Equipment) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Premises and Equipment [Line Items]
Premises and Equipment, gross	674,380us-gaap_PropertyPlantAndEquipmentGross	$ 639,537us-gaap_PropertyPlantAndEquipmentGross
Less accumulated depreciation and amortization	342,083	312,483
Premises and Equipment, net	332,297us-gaap_PropertyPlantAndEquipmentNet	327,054us-gaap_PropertyPlantAndEquipmentNet
Land
Premises and Equipment [Line Items]
Premises and Equipment, gross	60,397	64,810
Buildings
Premises and Equipment [Line Items]
Premises and Equipment, gross	308,144	310,345
Equipment
Premises and Equipment [Line Items]
Premises and Equipment, gross	176,906	156,521
Leasehold improvements
Premises and Equipment [Line Items]
Premises and Equipment, gross	25,151	23,872
Software
Premises and Equipment [Line Items]
Premises and Equipment, gross	103,782	$ 83,989
Minimum \| Buildings
Premises and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	10 years
Minimum \| Equipment
Premises and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	3 years
Minimum \| Leasehold improvements
Premises and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	1 year
Minimum \| Software
Premises and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	3 years
Maximum \| Buildings
Premises and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	35 years
Maximum \| Equipment
Premises and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	15 years
Maximum \| Leasehold improvements
Premises and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	20 years
Maximum \| Software
Premises and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	7 years

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.14)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 14

-Article 5

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	credit
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- Definition

Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.13)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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- Details

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- Definition

Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.13)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 13

-Subparagraph a

-Article 5

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 8

-Article 7

+ Details

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- Definition

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

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