Goodwill and Other Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Goodwill [Roll Forward]
Balance, January 1	$ 22,577	$ 0
Acquired	0	21,730
Balance, March 31	22,577	21,730
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Net Carrying Amount	17,866		19,072
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Remainder of 2013	4,853
2014	3,406
2015	2,416
2016	1,316
2017	1,215
2018	1,126
Core deposit intangibles [Member]
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Gross Carrying Amount	55,873		55,420
Accumulated Amortization	39,644		38,029
Net Carrying Amount	16,229		17,391
Other [Member]
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Gross Carrying Amount	1,800		1,800
Accumulated Amortization	163		119
Net Carrying Amount	$ 1,637		$ 1,681

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

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-Name Accounting Standards Codification

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Amount of amortization expense expected to be recognized in the next rolling twelve months following the latest balance sheet presented for assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount of amortization expense expected to be recognized in the remainder of the fiscal year following the latest fiscal year ended for assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount of amortization expense expected to be recognized during the fifth fiscal year following the latest fiscal year for assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount of amortization expense expected to be recognized during the second fiscal year following the latest fiscal year for assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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

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

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Carrying amount as of the balance sheet date, which is the cumulative amount paid and (if applicable) the fair value of any noncontrolling interest in the acquiree, adjusted for any amortization recognized prior to the adoption of any changes in generally accepted accounting principles (as applicable) and for any impairment charges, in excess of the fair value of net assets acquired in one or more business combination transactions.

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The aggregate amount of goodwill acquired in the period and allocated to the reportable segment. The value is stated at fair value based on the purchase price allocation.

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