Regulatory Capital (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Risk weighted assets	$ 7,500,000	$ 7,140,000	$ 6,990,000
Chemical Financial Corporation [Member]
Total Capital to Risk-Weighted Assets:
Actual, Capital Amount	851,114	841,257	816,595
Minimum Required for Capital Adequacy Purposes, Capital Amount	$ 599,743	$ 571,509	$ 559,273
Actual, Ratio	11.40%	11.80%	11.60%
Minimum Required for Capital Adequacy Purposes, Ratio	8.00%	8.00%	8.00%
Tier 1 Capital to Risk-Weighted Assets:
Actual, Capital Amount	$ 779,608	$ 767,929	$ 741,654
Minimum Required for Capital Adequacy Purposes, Capital Amount	$ 449,807	$ 428,631	$ 419,455
Actual, Ratio	10.40%	10.70%	10.60%
Minimum Required for Capital Adequacy Purposes, Ratio	6.00%	6.00%	6.00%
Common Equity Tier 1 Capital to Risk-Weighted Assets:
Actual, Capital Amount	$ 779,608	$ 753,815	$ 723,654
Minimum Required for Capital Adequacy Purposes, Capital Amount	$ 337,355	$ 321,474	$ 314,591
Actual, Ratio	10.40%	10.60%	10.40%
Minimum Required for Capital Adequacy Purposes, Ratio	4.50%	4.50%	4.50%
Leverage Ratio:
Actual, Capital Amount	$ 779,608	$ 767,929	$ 741,654
Minimum Required for Capital Adequacy Purposes, Capital Amount	$ 361,408	$ 356,396	$ 314,344
Actual, Ratio	8.60%	8.60%	9.40%
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	$ 854,189	$ 830,294	$ 713,999
Minimum Required for Capital Adequacy Purposes, Capital Amount	598,142	570,073	471,422
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount	$ 747,677	$ 712,591	$ 589,277
Actual, Ratio	11.40%	11.70%	12.00%
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	$ 782,683	$ 756,966	$ 640,324
Minimum Required for Capital Adequacy Purposes, Capital Amount	448,606	427,555	353,566
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount	$ 598,142	$ 570,073	$ 471,422
Actual, Ratio	10.50%	10.60%	10.90%
Minimum Required for Capital Adequacy Purposes, Ratio	6.00%	6.00%	6.00%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio	8.00%	8.00%	8.00%
Common Equity Tier 1 Capital to Risk-Weighted Assets:
Actual, Capital Amount	$ 782,683	$ 756,966	$ 640,324
Minimum Required for Capital Adequacy Purposes, Capital Amount	336,455	320,666	265,175
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount	$ 485,990	$ 463,184	$ 383,030
Actual, Ratio	10.50%	10.60%	10.90%
Minimum Required for Capital Adequacy Purposes, Ratio	4.50%	4.50%	4.50%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio	6.50%	6.50%	6.50%
Leverage Ratio:
Actual, Capital Amount	$ 782,683	$ 756,966	$ 640,324
Minimum Required for Capital Adequacy Purposes, Capital Amount	360,746	355,911	300,703
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount	$ 450,932	$ 444,888	$ 375,878
Actual, Ratio	8.70%	8.50%	8.50%
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%
The Bank of Holland [Member]
Total Capital to Risk-Weighted Assets:
Actual, Capital Amount			$ 77,648
Minimum Required for Capital Adequacy Purposes, Capital Amount			61,028
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount			$ 76,285
Actual, Ratio			10.20%
Minimum Required for Capital Adequacy Purposes, Ratio			8.00%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio			10.00%
Tier 1 Capital to Risk-Weighted Assets:
Actual, Capital Amount			$ 76,312
Minimum Required for Capital Adequacy Purposes, Capital Amount			45,771
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount			$ 61,028
Actual, Ratio			10.00%
Minimum Required for Capital Adequacy Purposes, Ratio			6.00%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio			8.00%
Common Equity Tier 1 Capital to Risk-Weighted Assets:
Actual, Capital Amount			$ 76,312
Minimum Required for Capital Adequacy Purposes, Capital Amount			34,328
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount			$ 49,585
Actual, Ratio			10.00%
Minimum Required for Capital Adequacy Purposes, Ratio			4.50%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio			6.50%
Leverage Ratio:
Actual, Capital Amount			$ 76,312
Minimum Required for Capital Adequacy Purposes, Capital Amount			30,710
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount			$ 38,388
Actual, Ratio			9.90%
Minimum Required for Capital Adequacy Purposes, Ratio			4.00%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio			5.00%
The Bank of Northern Michigan [Member]
Total Capital to Risk-Weighted Assets:
Actual, Capital Amount			$ 32,779
Minimum Required for Capital Adequacy Purposes, Capital Amount			25,878
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount			$ 32,347
Actual, Ratio			10.10%
Minimum Required for Capital Adequacy Purposes, Ratio			8.00%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio			10.00%
Tier 1 Capital to Risk-Weighted Assets:
Actual, Capital Amount			$ 32,779
Minimum Required for Capital Adequacy Purposes, Capital Amount			19,408
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount			$ 25,878
Actual, Ratio			10.10%
Minimum Required for Capital Adequacy Purposes, Ratio			6.00%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio			8.00%
Common Equity Tier 1 Capital to Risk-Weighted Assets:
Actual, Capital Amount			$ 32,779
Minimum Required for Capital Adequacy Purposes, Capital Amount			14,556
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount			$ 21,025
Actual, Ratio			10.10%
Minimum Required for Capital Adequacy Purposes, Ratio			4.50%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio			6.50%
Leverage Ratio:
Actual, Capital Amount			$ 32,779
Minimum Required for Capital Adequacy Purposes, Capital Amount			14,421
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Capital Amount			$ 18,026
Actual, Ratio			9.10%
Minimum Required for Capital Adequacy Purposes, Ratio			4.00%
Required to be Well Capitalized Under Prompt Corrective Action Regulations, Ratio			5.00%