Accumulated Other Comprehensive Loss (Details Textual) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011
Accumulated Other Comprehensive Loss (Textual) [Abstract]
Net unrealized gains on investment securities-available-for-sale, tax expense	$ 2,542	$ 1,796	$ 1,925
Pension and other postretirement benefits adjustment, tax benefit	$ 14,876	$ 15,435	$ 9,195

Accumulated appreciation or loss, tax, in value of the total of available-for-sale securities at the end of an accounting period.

No definition available.

Name:	chfc_AccumulatedOtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentTax
Namespace Prefix:	chfc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant