Pension and Other Postretirement Benefit Plans (Textual) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Contribution to corporation's pension plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Contribution to defined benefit pension plan		$ 15.0
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	5.00%
Chemical Financial Corporation [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of eligible pay contribution to certain employees	4.00%
Defined Contribution Plan, Employer Total Contribution Amount	$ 0.8	$ 0.9