Regulatory Capital (Tables)

9 Months Ended

Sep. 30, 2012

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

	Actual				Minimum Required for Capital Adequacy Purposes				Required to be Well Capitalized Under Prompt Corrective Action Regulations
	Capital Amount		Ratio		Capital Amount		Ratio		Capital Amount		Ratio
	(Dollars in thousands)
September 30, 2012
Total Capital to Risk-Weighted Assets:
Corporation	$	549,388	13.6	%	$	322,212	8.0	%	N/A		N/A
Chemical Bank	537,467		13.4		321,585		8.0		$	401,982	10.0	%
Tier 1 Capital to Risk-Weighted Assets:
Corporation	498,618		12.4		161,106		4.0		N/A		N/A
Chemical Bank	486,794		12.1		160,793		4.0		241,189		6.0
Leverage Ratio:
Corporation	498,618		9.4		211,670		4.0		N/A		N/A
Chemical Bank	486,794		9.2		211,452		4.0		264,315		5.0
December 31, 2011
Total Capital to Risk-Weighted Assets:
Corporation	$	517,547	13.3	%	$	310,316	8.0	%	N/A		N/A
Chemical Bank	510,290		13.2		310,119		8.0		$	387,649	10.0	%
Tier 1 Capital to Risk-Weighted Assets:
Corporation	468,565		12.1		155,158		4.0		N/A		N/A
Chemical Bank	461,338		11.9		155,060		4.0		232,589		6.0
Leverage Ratio:
Corporation	468,565		9.0		208,013		4.0		N/A		N/A
Chemical Bank	461,338		8.9		208,033		4.0		260,042		5.0
September 30, 2011
Total Capital to Risk-Weighted Assets:
Corporation	$	493,976	13.1	%	$	302,360	8.0	%	N/A		N/A
Chemical Bank	486,207		12.9		302,149		8.0		$	377,686	10.0	%
Tier 1 Capital to Risk-Weighted Assets:
Corporation	446,217		11.8		151,180		4.0		N/A		N/A
Chemical Bank	438,480		11.6		151,074		4.0		226,612		6.0
Leverage Ratio:
Corporation	446,217		8.6		206,656		4.0		N/A		N/A
Chemical Bank	438,480		8.5		206,613		4.0		258,266		5.0