Business Combinations (Acquisition Proforma Details) (Details) (Citizens Republic Bancorp, USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014
Citizens Republic Bancorp
Business Acquisition, Pro-forma Information [Line Items]
Business Acquisition, Pro Forma Revenue	$ 1,096,960
Business Acquisition, Pro Forma Net Income (Loss)	$ 196,744

The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (h)(2)-(3)

-URI http://asc.fasb.org/extlink&oid=25497992&loc=d3e1392-128463

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration