Regulatory Capital and Reserve Requirements (Tables)

12 Months Ended

Dec. 31, 2016

Banking and Thrift [Abstract]

Corporation's and Chemical Bank's actual capital amounts and ratios with the quantitative measures established by regulation to ensure capital adequacy

The summary below compares the actual capital amounts and ratios with the quantitative measures established by regulation to ensure capital adequacy:

	Actual				Minimum Required for Capital Adequacy Purposes				Minimum Required for Capital Adequacy Purposes Plus Capital Conservation Buffer				Required to be Well Capitalized Under Prompt Corrective  Action Regulations
(Dollars in thousands)	Capital Amount		Ratio		Capital Amount		Ratio		Capital Amount		Ratio		Capital Amount		Ratio
December 31, 2016
Total Capital to Risk-Weighted Assets
Corporation	$	1,543,018	11.5	%	$	1,073,431	8.0	%	$	1,157,293	8.6	%	N/A		N/A
Chemical Bank	1,608,980		12.0		1,068,560		8.0		1,152,041		8.6		$	1,335,700	10.0	%
Tier 1 Capital to Risk-Weighted Assets
Corporation	1,441,209		10.7		805,073		6.0		888,935		6.6		N/A		N/A
Chemical Bank	1,522,711		11.4		801,420		6.0		884,901		6.6		1,068,560		8.0
Common Equity Tier 1 Capital to Risk-Weighted Assets
Corporation	1,441,209		10.7		603,805		4.5		687,667		5.1		N/A		N/A
Chemical Bank	1,522,711		11.4		601,065		4.5		684,546		5.1		868,205		6.5
Leverage Ratio
Corporation	1,441,209		9.0		643,603		4.0		643,603		4.0		N/A		N/A
Chemical Bank	1,522,711		9.5		641,457		4.0		641,457		4.0		801,822		5.0
December 31, 2015
Total Capital to Risk-Weighted Assets
Corporation	$	841,257	11.8	%	$	571,509	8.0	%	N/A		N/A		N/A		N/A
Chemical Bank	830,294		11.7		570,073		8.0		N/A		N/A		$	712,591	10.0	%
Tier 1 Capital to Risk-Weighted Assets
Corporation	767,929		10.7		428,631		6.0		N/A		N/A		N/A		N/A
Chemical Bank	756,966		10.6		427,555		6.0		N/A		N/A		570,073		8.0
Common Equity Tier 1 Capital to Risk-Weighted Assets
Corporation	753,815		10.6		321,474		4.5		N/A		N/A		N/A		N/A
Chemical Bank	756,966		10.6		320,666		4.5		N/A		N/A		463,184		6.5
Leverage Ratio
Corporation	767,929		8.6		356,396		4.0		N/A		N/A		N/A		N/A
Chemical Bank	756,966		8.5		355,911		4.0		N/A		N/A		444,888		5.0