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

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-Name Accounting Standards Codification

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

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Goodwill and Other Intangible Assets (Schedule of Goodwill) (Details) (USD $) In Thousands, unless otherwise specified	0 Months Ended
	Apr. 12, 2013	Dec. 31, 2014	Dec. 31, 2013
Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross		$ 96,561	$ 101,873
Goodwill		741,740us-gaap_Goodwill	741,740us-gaap_Goodwill
Finite-Lived Intangible Assets, Accumulated Amortization		25,541	19,118
Finite-Lived Intangible Assets, Net		71,020us-gaap_FiniteLivedIntangibleAssetsNet	82,755us-gaap_FiniteLivedIntangibleAssetsNet
Commercial
Goodwill [Line Items]
Goodwill		527,406	527,406
Retail
Goodwill [Line Items]
Goodwill		193,961	193,961
Wealth
Goodwill [Line Items]
Goodwill		20,373	20,373
Citizens Republic Bancorp
Goodwill [Line Items]
Goodwill, Acquired During Period	281,694
Core Deposits
Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross		82,323	87,533
Finite-Lived Intangible Assets, Accumulated Amortization		19,996	16,065
Finite-Lived Intangible Assets, Net		62,327	71,468
Noncompete Agreements
Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross			102
Finite-Lived Intangible Assets, Accumulated Amortization			102
Finite-Lived Intangible Assets, Net			0
Lease Agreements
Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross		238	238
Finite-Lived Intangible Assets, Accumulated Amortization		176	140
Finite-Lived Intangible Assets, Net		62	98
Customer Relationships
Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross			14,000
Finite-Lived Intangible Assets, Accumulated Amortization			2,811
Finite-Lived Intangible Assets, Net			11,189
Customer Relationships \| Citizens Republic Bancorp
Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross		14,000
Finite-Lived Intangible Assets, Accumulated Amortization		5,369
Finite-Lived Intangible Assets, Net		$ 8,631