Regulatory Capital (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Regulatory Capital
Risk weighted assets	$ 13,430,000	$ 7,140,000
Corporation [Member]
Total Capital to Risk-Weighted Assets
Actual Amount	$ 1,491,389	$ 841,257
Actual Ratio	11.10%	11.80%
For Capital Adequacy Purposes Amount	$ 1,074,506	$ 571,509
For Capital Adequacy Purposes Ratio	8.00%	8.00%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount	$ 1,155,093
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio	8.60%
Tier 1 Capital to Risk-Weighted Assets
Actual Amount	$ 1,413,464	$ 767,929
Actual Ratio	10.50%	10.70%
For Capital Adequacy Purposes Amount	$ 805,879	$ 428,631
For Capital Adequacy Purposes Ratio	6.00%	6.00%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount	$ 886,467
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio	6.60%
Common Equity Tier 1 Capital to Risk-Weighted Assets
Actual Amount	$ 1,413,464	$ 753,815
Actual Ratio	10.50%	10.60%
For Capital Adequacy Purposes Amount	$ 604,409	$ 321,474
For Capital Adequacy Purposes Ratio	4.50%	4.50%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount	$ 684,997
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio	5.10%
Leverage Ratio
Actual Amount	$ 1,413,464	$ 767,929
Actual Ratio	12.80%	8.60%
For Capital Adequacy Purposes Amount	$ 442,317	$ 356,396
For Capital Adequacy Purposes Ratio	4.00%	4.00%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount	$ 442,317
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio	4.00%
Chemical Bank [Member]
Total Capital to Risk-Weighted Assets
Actual Amount	$ 825,504	$ 830,294
Actual Ratio	10.80%	11.70%
For Capital Adequacy Purposes Amount	$ 614,281	$ 570,073
For Capital Adequacy Purposes Ratio	8.00%	8.00%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount	$ 660,352
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio	8.60%
To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 767,851	$ 712,591
To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	10.00%	10.00%
Tier 1 Capital to Risk-Weighted Assets
Actual Amount	$ 752,957	$ 756,966
Actual Ratio	9.80%	10.60%
For Capital Adequacy Purposes Amount	$ 460,711	$ 427,555
For Capital Adequacy Purposes Ratio	6.00%	6.00%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount	$ 506,782
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio	6.60%
To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 614,281	$ 570,073
To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	8.00%	8.00%
Common Equity Tier 1 Capital to Risk-Weighted Assets
Actual Amount	$ 752,957	$ 756,966
Actual Ratio	9.80%	10.60%
For Capital Adequacy Purposes Amount	$ 345,533	$ 320,666
For Capital Adequacy Purposes Ratio	4.50%	4.50%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount	$ 391,604
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio	5.10%
To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 499,103	$ 463,184
To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	6.50%	6.50%
Leverage Ratio
Actual Amount	$ 752,957	$ 756,966
Actual Ratio	8.10%	8.50%
For Capital Adequacy Purposes Amount	$ 373,897	$ 355,911
For Capital Adequacy Purposes Ratio	4.00%	4.00%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount	$ 373,897
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio	4.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 467,371	$ 444,888
To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	5.00%	5.00%
Talmer Bank [Member]
Total Capital to Risk-Weighted Assets
Actual Amount	$ 719,213
Actual Ratio	12.70%
For Capital Adequacy Purposes Amount	$ 453,090
For Capital Adequacy Purposes Ratio	8.00%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount	$ 487,071
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio	8.60%
To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 566,362
To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	10.00%
Tier 1 Capital to Risk-Weighted Assets
Actual Amount	$ 713,835
Actual Ratio	12.60%
For Capital Adequacy Purposes Amount	$ 339,817
For Capital Adequacy Purposes Ratio	6.00%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount	$ 373,799
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio	6.60%
To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 453,090
To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	8.00%
Common Equity Tier 1 Capital to Risk-Weighted Assets
Actual Amount	$ 713,835
Actual Ratio	12.60%
For Capital Adequacy Purposes Amount	$ 254,863
For Capital Adequacy Purposes Ratio	4.50%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount	$ 288,845
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio	5.10%
To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 368,135
To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	6.50%
Leverage Ratio
Actual Amount	$ 713,835
Actual Ratio	10.90%
For Capital Adequacy Purposes Amount	$ 262,318
For Capital Adequacy Purposes Ratio	4.00%
For Capital Adequacy Purposes Plus Capital Conservation Buffer Amount	$ 262,318
For Capital Adequacy Purposes Plus Capital Conservation Buffer Ratio	4.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 327,898
To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	5.00%