Cover Page - shares	6 Months Ended
	Dec. 31, 2021	Jan. 26, 2022
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Dec. 31, 2021
Document Transition Report	false
Entity File Number	1-5828
Entity Registrant Name	CARPENTER TECHNOLOGY CORPORATION
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	23-0458500
Entity Address, Address Line One	1735 Market Street
Entity Address, Address Line Two	15th Floor
Entity Address, City or Town	Philadelphia,
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	19103
City Area Code	610
Local Phone Number	208-2000
Title of 12(b) Security	Common Stock, $5 Par Value
Trading Symbol	CRS
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		48,269,470
Entity Central Index Key	0000017843
Amendment Flag	false
Current Fiscal Year End Date	--06-30
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q2