Regulatory Capital (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Risk weighted assets	$ 5,060,000,000	$ 4,640,000,000	$ 4,510,000,000
Chemical Financial Corporation [Member]
Total Capital to Risk-Weighted Assets:
Actual, Capital Amount	760,324,000	649,836,000	638,786,000
Minimum Required for Capital Adequacy Purposes, Capital Amount	404,420,000	371,465,000	361,199,000
Actual, Ratio	15.00%	14.00%	14.20%
Minimum Required for Capital Adequacy Purposes, Ratio	8.00%	8.00%	8.00%
Tier 1 Capital to Risk-Weighted Assets:
Actual, Capital Amount	696,963,000	591,535,000	582,039,000
Minimum Required for Capital Adequacy Purposes, Capital Amount	202,210,000	185,732,000	180,600,000
Actual, Ratio	13.80%	12.70%	12.90%
Minimum Required for Capital Adequacy Purposes, Ratio	4.00%	4.00%	4.00%
Leverage Ratio:
Actual, Capital Amount	696,963,000	591,535,000	582,039,000
Minimum Required for Capital Adequacy Purposes, Capital Amount	251,133,000	239,010,000	232,972,000
Actual, Ratio	11.10%	9.90%	10.00%
Minimum Required for Capital Adequacy Purposes, Ratio	4.00%	4.00%	4.00%
Chemical Bank [Member]
Total Capital to Risk-Weighted Assets:
Actual, Capital Amount	613,673,000	579,494,000	568,626,000
Minimum Required for Capital Adequacy Purposes, Capital Amount	403,840,000	370,881,000	360,617,000
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount	504,799,000	463,601,000	450,771,000
Actual, Ratio	12.20%	12.50%	12.60%
Minimum Required for Capital Adequacy Purposes, Ratio	8.00%	8.00%	8.00%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio	10.00%	10.00%	10.00%
Tier 1 Capital to Risk-Weighted Assets:
Actual, Capital Amount	550,401,000	521,283,000	511,969,000
Minimum Required for Capital Adequacy Purposes, Capital Amount	201,920,000	185,440,000	180,309,000
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount	302,880,000	278,160,000	270,463,000
Actual, Ratio	10.90%	11.20%	11.40%
Minimum Required for Capital Adequacy Purposes, Ratio	4.00%	4.00%	4.00%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio	6.00%	6.00%	6.00%
Leverage Ratio:
Actual, Capital Amount	550,401,000	521,283,000	511,969,000
Minimum Required for Capital Adequacy Purposes, Capital Amount	250,986,000	238,884,000	232,828,000
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount	$ 313,732,000	$ 298,605,000	$ 291,034,000
Actual, Ratio	8.80%	8.70%	8.80%
Minimum Required for Capital Adequacy Purposes, Ratio	4.00%	4.00%	4.00%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio	5.00%	5.00%	5.00%

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The amount of total capital as defined in the regulations.

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The amount of Total Capital required to be categorized as well as capitalized under the regulatory framework for prompt corrective action.

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Total Capital divided by risk weighted assets as defined in the regulations.

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Amount of risk-weighted assets as calculated in accordance with U.S. Federal regulatory capital standards.

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Tier 1 Leverage Capital as defined in the regulations. Also called Core Capital.

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Tier 1 Risk Based Capital as defined in the regulations.

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Tier 1 capital divided by risk weighted assets as defined by regulations.

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