Retirement Plans (Textual) (Details) $ in Thousands		12 Months Ended
	Aug. 31, 2016 USD ($)	Dec. 31, 2016 USD ($) employee shares	Dec. 31, 2015 USD ($) shares	Dec. 31, 2014 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Percentage of eligible pay contribution to certain employees		4.00%
Common Stock, Shares Held by Plan | shares		70,599,133	38,167,861
Dividends paid (in dollars per share)		$ 49,389	$ 36,918	$ 29,528
Multiemployer Plan, Period Contributions		0
Multiemployer Plan, Participating Company, Allocation of Plan Liabilities		$ 3,500	2,600
Multiemployer Plan, Company's Asset Participation Level		5.00%
Employer discretionary contribution percent		4.00%
Employer total contribution amount		$ 6,500	4,700	3,300
Contribution to 401(k) savings plan		$ 3,500	3,100	2,300
Maximum annual contribution per employee percent		50.00%
Employer matching contribution percent		4.00%
Employer matching contribution amount		$ 3,000	1,600	1,000
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Maximum years of vested service for calculation of retirement benefits		30 years
Years of employees highest average salary for calculation of retirement benefits		5 years
Number of years preceding retirement for calculation of retirement benefits		10 years
Maximum years of service for which pension benefits calculation is based upon vested service and average five years of salary		15 years
Number of Employees Covered (in employee) | employee		135
Maximum total years of age and years of service for which pension benefits calculation is based upon vested service and average five years of salary		65 years
Pension Plan expense		$ 73	1,575	$ (45)
Employer contributions		$ 0	$ 0
Discount rate used in determining benefit obligation		4.22%	4.55%	4.15%
Discount rate used in determining expense		4.55%	4.15%	5.00%
Pension plan actual asset allocations		100.00%	100.00%
Projected benefit obligation		$ 123,968	$ 119,873	$ 129,160
Accumulated benefit obligation		$ 115,418	$ 109,583
Pension Plan | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations range - minimum		40.00%
Target plan asset allocations range - maximum		70.00%
Pension plan actual asset allocations		69.00%	68.00%
Pension Plan | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations range - minimum		20.00%
Target plan asset allocations range - maximum		60.00%
Pension plan actual asset allocations		29.00%	31.00%
Pension Plan | Other
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations range - minimum		0.00%
Target plan asset allocations range - maximum		10.00%
Pension plan actual asset allocations		2.00%	1.00%
Pension Plan | Common Stock
Defined Benefit Plan Disclosure [Line Items]
Common Stock, Shares Held by Plan | shares		210,663	210,663.000
Fair value of common stock		$ 11,400	$ 7,200
Pension plan actual asset allocations		8.60%	5.70%
Supplemental Plan
Defined Benefit Plan Disclosure [Line Items]
Defined benefits owed related to change in control	$ 1,900
Discount rate used in determining benefit obligation		3.63%	4.51%	4.07%
Discount rate used in determining expense		4.51%	4.07%	4.87%
Number of employees covered by the pension plan | employee		1
Projected benefit obligation		$ 2,600	$ 2,200
Accumulated benefit obligation		2,200	1,800
Supplemental Plan expense		500	400	$ 300
Postretirement Plan
Defined Benefit Plan Disclosure [Line Items]
Pension Plan expense		158	278	$ 186
Employer contributions		$ 309	$ 241
Discount rate used in determining benefit obligation		3.79%	4.23%	3.75%
Discount rate used in determining expense		4.23%	3.75%	4.27%
Expected health care cost trend rate assumed for 2014		7.00%
Expected ultimate health care cost trend rate in 2020		5.00%
Projected benefit obligation		$ 2,601	$ 3,247	$ 3,702
Accumulated benefit obligation		$ 2,601	3,247
Minimum retirement age (years)		50 years
Maximum benefit age of spouse (years)		65 years
Minimum retirement age with twenty-five years of service to be eligible for postretirement benefits (years)		60 years
Minimum years of service for retirees at age sixty to be eligible for postretirement benefits (years)		25 years
Chemical Financial Corporation | Pension Plan | Common Stock
Defined Benefit Plan Disclosure [Line Items]
Dividends paid (in dollars per share)		$ 200	$ 200