Regulatory Capital (Tables)

6 Months Ended

Jun. 30, 2018

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
June 30, 2018
Total Capital to Risk-Weighted Assets
Corporation	$	1,732,830	11.4	%	$	1,212,912	8.0	%	$	1,497,188	9.9	%	N/A		N/A
Chemical Bank	1,725,300		11.4		1,210,346		8.0		1,494,021		9.9		$	1,512,932	10.0	%
Tier 1 Capital to Risk-Weighted Assets
Corporation	1,609,206		10.6		909,684		6.0		1,193,960		7.9		N/A		N/A
Chemical Bank	1,617,483		10.7		907,759		6.0		1,191,434		7.9		1,210,346		8.0
Common Equity Tier 1 Capital to Risk-Weighted Assets
Corporation	1,609,206		10.6		682,263		4.5		966,539		6.4		N/A		N/A
Chemical Bank	1,617,483		10.7		680,819		4.5		964,494		6.4		983,406		6.5
Leverage Ratio
Corporation	1,609,206		8.6		747,999		4.0		747,999		4.0		N/A		N/A
Chemical Bank	1,617,483		8.7		747,112		4.0		747,112		4.0		933,891		5.0
December 31, 2017
Total Capital to Risk-Weighted Assets
Corporation	$	1,614,046	11.0	%	$	1,179,076	8.0	%	$	1,363,307	9.3	%	N/A		N/A
Chemical Bank	1,613,087		11.0		1,176,361		8.0		1,360,167		9.3		$	1,470,451	10.0	%
Tier 1 Capital to Risk-Weighted Assets
Corporation	1,498,463		10.2		884,307		6.0		1,068,538		7.3		N/A		N/A
Chemical Bank	1,513,219		10.3		882,271		6.0		1,066,077		7.3		1,176,361		8.0
Common Equity Tier 1 Capital to Risk-Weighted Asset
Corporation	1,498,463		10.2		663,230		4.5		847,461		5.8		N/A		N/A
Chemical Bank	1,513,219		10.3		661,703		4.5		854,509		5.8		955,793		6.5
Leverage Ratio
Corporation	1,498,463		8.3		720,890		4.0		720,890		4.0		N/A		N/A
Chemical Bank	1,513,219		8.4		720,043		4.0		720,043		4.0		900,053		5.0