Loans, Allowance for Loan and Lease Losses, and Reserve for Off-Balance Sheet Credit Commitments (Details 3) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Changes in Accretable Yield for Acquired Impaired Loans
Balance at the beginning of the period	$ 219,018	$ 295,813
Accretion	(46,397)	(62,810)
Reclassification from nonaccretable difference	33,917	36,091
Disposals and other	(38,069)	(50,076)
Balance at the end of the period	168,469	219,018
Acquired loans
FDIC indemnification asset	$ 50,511us-gaap_FDICIndemnificationAsset	$ 89,227us-gaap_FDICIndemnificationAsset

Amount of the excess of a loan's cash flows expected to be collected over the investor's initial investment in acquired loans not accounted for as debt securities with evidence of deterioration of credit quality.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 30

-Section 15

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=27045933&loc=d3e13503-111538

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(2)

-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

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- Definition

Amount of decrease from accretion of the excess of a loan's cash flows expected to be collected over the investor's initial investment in acquired loans not accounted for as debt securities with evidence of deterioration of credit quality.

+ References

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- Definition

Amount of reduction, resulting from a sale or transfer of a loan, in the excess of a loan's cash flows expected to be collected over the investor's initial investment in acquired loans not accounted for as debt securities with evidence of deterioration of credit quality.

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Amount of decrease from reclassification to nonaccretable difference of the excess of a loan's cash flows expected to be collected over the investor's initial investment in acquired loans not accounted for as debt securities with evidence of deterioration of credit quality.

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- Definition

Carrying amount of receivable assets originating from the indemnification agreement with the Federal Deposit Insurance Corporation (FDIC), in which the FDIC is to partially cover losses.

+ References

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