Lease Termination Costs (Details)	6 Months Ended
Jul. 01, 2013	Jul. 02, 2012
Lease Termination Costs
Number of locations closed, for which lease termination costs were incurred	3	1

Represents the number of locations closed, for which lease termination costs were incurred.

No definition available.

Name:	cosi_NumberOfLocationsClosedForWhichLeaseTerminationCostsWereIncurred
Namespace Prefix:	cosi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration