Regulatory Capital (Tables)

9 Months Ended

Sep. 30, 2017

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
September 30, 2017
Total Capital to Risk-Weighted Assets
Corporation	$	1,626,898	11.2	%	$	1,160,602	8.0	%	$	1,341,946	9.3	%	N/A		N/A
Chemical Bank	1,619,878		11.2		1,158,070		8.0		1,339,019		9.3		$	1,447,588	10.0	%
Tier 1 Capital to Risk-Weighted Assets
Corporation	1,517,561		10.5		870,451		6.0		1,051,795		7.3		N/A		N/A
Chemical Bank	1,526,212		10.5		868,553		6.0		1,049,501		7.3		1,158,070		8.0
Common Equity Tier 1 Capital to Risk-Weighted Assets
Corporation	1,517,561		10.5		652,839		4.5		834,183		5.8		N/A		N/A
Chemical Bank	1,526,212		10.5		651,414		4.5		832,363		5.8		940,932		6.5
Leverage Ratio
Corporation	1,517,561		8.6		707,330		4.0		707,330		4.0		N/A		N/A
Chemical Bank	1,526,212		8.6		706,323		4.0		706,323		4.0		882,903		5.0
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 Asset
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