(Schedule of Assumptions Used) (Details)	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
End of year \| Supplemental Executive Retirement Nonqualified Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	3.99%	3.61%	4.12%
Nonqualified pensions	3.75%	3.75%	3.75%
End of year \| Medical Trend Rates, Non-Medicare Risk, Under Age 65, Percent
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Initial trend		7.00%	7.50%
Ultimate trend		5.00%	5.00%
Year ultimate trend reached		2019	2019
End of year \| Medical Trend Rates, Non-Medicare Risk, After Age 65, Percent
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Initial trend		11.00%	11.50%
Ultimate trend		5.00%	5.00%
Year ultimate trend reached		2027	2027
End of year \| Prescription Drugs
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Initial trend		7.00%	7.50%
Ultimate trend		5.00%	5.00%
Year ultimate trend reached		2019	2019
Beginning of year \| Supplemental Executive Retirement Nonqualified Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	3.61%	4.12%	4.21%
Nonqualified pensions	3.75%	3.75%	3.75%
Beginning of year \| Medical Trend Rates, Non-Medicare Risk, Under Age 65, Percent
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Initial trend	7.00%	7.50%	8.00%
Ultimate trend	5.00%	5.00%	5.00%
Year ultimate trend reached	2019	2019	2019
Beginning of year \| Medical Trend Rates, Non-Medicare Risk, After Age 65, Percent
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Initial trend	11.50%	11.50%	12.00%
Ultimate trend	5.00%	5.00%	5.00%
Year ultimate trend reached	2027	2027	2027
Beginning of year \| Prescription Drugs
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Initial trend	7.50%	7.50%	8.00%
Ultimate trend	5.00%	5.00%	5.00%
Year ultimate trend reached	2019	2019	2019
Pension Benefits \| End of year
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	4.57%	4.19%	4.99%
Expected long-term rate of return	6.00%	6.50%	6.75%
Pension Benefits \| Beginning of year
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	4.19%	4.99%	4.21%
Postretirement Benefits \| End of year
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	1.76%	3.50%	4.01%
Postretirement Benefits \| End of year \| Citizens Republic Bancorp
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	1.77%	3.61%	3.98%
Postretirement Benefits \| Beginning of year
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	3.50%	4.01%	3.18%
Postretirement Life Insurance \| End of year
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	4.79%	4.36%	5.08%
Postretirement Life Insurance \| Beginning of year
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	4.36%	5.08%	4.30%
Expected long-term rate of return	6.50%	6.75%	7.00%

The interest rate used to adjust for the time value of money for the plan.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(1)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

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- Definition

Expected rate of compensation increases (for pay-related plans).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(2)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

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- Definition

An assumption as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invested or to be invested to provide for the benefits included in the benefit obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Expected Long-Term Rate of Return on Plan Assets
-URI http://asc.fasb.org/extlink&oid=6512046

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(3)
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The assumed health care cost trend rate for the next year used to measure the expected cost of benefits covered by the plan (gross eligible charges). This is based upon the annual rate of change in the cost of health care benefits currently provided by the postretirement benefit plan, due to factors other than changes in the composition of the plan population by age and dependency status.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Health Care Cost Trend Rate
-URI http://asc.fasb.org/extlink&oid=6514820

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (l)
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The ultimate trend rate for health care costs.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
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-Section 50
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Year the ultimate health care cost trend rate is expected to be reached, in CCYY format.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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