Goodwill, Core Deposit Premium and Other Intangible Assets (Carrying amount of intangible assets (incl accumulated amortization) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 71,566	$ 60,071
Accumulated Amortization	27,542	26,139
Net Carrying Amount	44,024	33,932
Core deposit intangibles
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	27,109	21,069
Accumulated Amortization	13,145	12,525
Net Carrying Amount	13,964	8,544
Mortgage servicing rights
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	38,893	37,825
Accumulated Amortization	13,398	12,841
Net Carrying Amount	25,495	24,984
Customer relationship intangible
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,177	1,177
Accumulated Amortization	784	773
Net Carrying Amount	393	404
Commercial servicing rights
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	4,387	0
Accumulated Amortization	215	0
Net Carrying Amount	$ 4,172	$ 0

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

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- Definition

Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

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- Definition

Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16212-109274

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph ((a)(1),(b))

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

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