Document And Entity Information (USD $)	12 Months Ended
	Dec. 31, 2012	Jun. 30, 2012	Feb. 22, 2013 Common Class A [Member]	Feb. 22, 2013 Common Class B
Document and Entity Information
Entity Registrant Name	CDI CORP
Entity Central Index Key	0000018396
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2012
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	FY
Amendment Flag	false
Reporting Status	Yes
Voluntary Filers	No
Well Known Seasoned Issuer	No
Entity Common Stock, Shares Outstanding			19,359,983	0
Public Float		$ 232,487,696