Parent Company Only Financial Statements Financial Position (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Assets [Abstract]
Investment securities available-for-sale	$ 748,864us-gaap_AvailableForSaleSecurities	$ 684,570us-gaap_AvailableForSaleSecurities
Premises and equipment	97,496us-gaap_PropertyPlantAndEquipmentNet	75,308us-gaap_PropertyPlantAndEquipmentNet
Goodwill	180,128us-gaap_Goodwill	120,164us-gaap_Goodwill
Other assets	141,467us-gaap_OtherAssets	132,781us-gaap_OtherAssets
Total Assets	7,322,143us-gaap_Assets	6,184,708us-gaap_Assets
Liabilities and Equity [Abstract]
Other liabilities	56,572us-gaap_OtherLiabilities	38,395us-gaap_OtherLiabilities
Shareholders' equity	797,133us-gaap_StockholdersEquity	696,500us-gaap_StockholdersEquity	596,341us-gaap_StockholdersEquity	571,729us-gaap_StockholdersEquity
Total Liabilities and Shareholders' Equity	7,322,143	6,184,708
Chemical Financial Corporation [Member]
Assets [Abstract]
Cash at subsidiary bank	45,820	65,358
Investment in subsidiary bank	745,045	625,156
Premises and equipment	3,601	3,902
Goodwill	1,092	1,092
Other assets	4,654	3,309
Total Assets	800,212	698,817
Liabilities and Equity [Abstract]
Other liabilities	3,079	2,317
Shareholders' equity	797,133	696,500
Total Liabilities and Shareholders' Equity	$ 800,212	$ 698,817

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Investment in Subsidiary Bank

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Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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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 liabilities and equity items, including the portion of equity attributable to noncontrolling interests, if any.

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The aggregate carrying amounts, as of the balance sheet date, of assets not separately disclosed in the balance sheet.

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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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