Pension and Other Postretirement Benefit Plans - Textual (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Corporation match as a percentage of the participants' elective deferrals	50.00%
Maximum percent of participants' base compensation matched	4.00%
Employer contributions to Pentegra DB Plan	$ 0	$ 0
Chemical Financial Corporation
Defined Benefit Plan Disclosure [Line Items]
Percentage of eligible pay contribution to certain employees (as a percent)	4.00%
Employer total contribution amount	$ 2,500,000	$ 1,300,000
Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Contribution to defined benefit pension plan	$ 0
Discount rate for pension plan expense (as a percent)	4.20%
Non-Qualified Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate for pension plan expense (as a percent)	3.60%