Document and Entity Information - USD ($)	12 Months Ended
	Jun. 30, 2015	Aug. 14, 2015	Dec. 31, 2014
Document and Entity Information
Entity Registrant Name	CARPENTER TECHNOLOGY CORP
Entity Central Index Key	0000017843
Document Type	10-K
Document Period End Date	Jun. 30, 2015
Amendment Flag	false
Current Fiscal Year End Date	--06-30
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 2,563,962,388
Entity Common Stock, Shares Outstanding		49,541,169
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	FY