Represents the discount amortization period of liability for future costs.

No definition available.

Name:	crs_LiabilityForFutureCostsDiscountAmortizationPeriod
Namespace Prefix:	crs_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of former operating facility site that the liability for future costs is discounted to present value.

+ References

No definition available.

+ Details

Name:	crs_NumberOfFormerOperatingFacilitySiteLiabilityForFutureCostsIsDiscountedToPresentValue
Namespace Prefix:	crs_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Other Than LIFO Inventory Amount

+ References

No definition available.

+ Details

Name:	crs_OtherThanLIFOInventoryAmount
Namespace Prefix:	crs_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Aggregate of: (i) sales discounts given by the entity, including, but not limited to, early payments of accounts due, (ii) cash rebates offered on sales, (iii) the total deduction from sales during the period, and (iv) price reductions (allowance, price protection agreements) given by the entity. Discounts, rebates, returns and allowances are a deduction from gross revenue in arriving at net revenue.

+ References

No definition available.

+ Details

Name:	crs_SalesDiscountsRebatesReturnsAndAllowances
Namespace Prefix:	crs_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

Name:	crs_SignificantAccountingPoliciesLineItems
Namespace Prefix:	crs_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Total costs accrued as of the balance sheet date for environmental loss contingencies.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 25
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6395460&loc=d3e13647-108346

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 30
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859

+ Details

Name:	us-gaap_AccrualForEnvironmentalLossContingencies
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Rate applied to the undiscounted amount of environmental loss contingencies to arrive at the present value recorded as of the balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 30
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 5.Y.Q1)
-URI http://asc.fasb.org/extlink&oid=27011672&loc=d3e149879-122751

+ Details

Name:	us-gaap_AccrualForEnvironmentalLossContingenciesDiscountRate
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e9054-108599

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6351-108592

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=123594938&loc=d3e13531-108611

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123594938&loc=d3e13537-108611

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

+ Details

Name:	us-gaap_ConcentrationRiskPercentage1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of reporting units tested for impairment of goodwill. A reporting unit is an operating segment or one level below an operating segment.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfReportingUnits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 912
-SubTopic 730
-Section 25
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6472174&loc=d3e58812-109433

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 985
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128462-111756

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 730
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6420194&loc=d3e21568-108373

+ Details

Name:	us-gaap_ResearchAndDevelopmentExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=crs_PerformanceEngineeredProductsSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConcentrationRiskByTypeAxis=us-gaap_CustomerConcentrationRiskMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConcentrationRiskByBenchmarkAxis=us-gaap_RevenueFromContractWithCustomerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_MajorCustomersAxis=crs_HowmetAerospaceInc.Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=crs_SpecialtyAlloysOperationsSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_SoftwareAndSoftwareDevelopmentCostsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_OtherIntangibleAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Summary of Significant Accounting Policies - Narrative (Details) $ in Millions	12 Months Ended
	Jun. 30, 2021 USD ($) reporting_unit facility	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)
Summary of significant accounting policies
Discounts, rebates, returns and allowances	$ 14.4	$ 25.8	$ 22.6
Research and development expenditures	19.7	28.0	$ 23.3
Inventory accounted under method other than LIFO	$ 107.5	$ 136.3
Number of reporting units \| reporting_unit	3
Number of former operating facility site that the liability for future costs is discounted to present value (facility) \| facility	1
Liability for future costs discount amortization period	20 years
Environmental expenditures, discount rate	3.00%	3.00%
Environmental expenditures, liability	$ 11.2	$ 11.2
Performance Engineered Products
Summary of significant accounting policies
Number of reporting units \| reporting_unit	2
Customer \| Sales Revenue \| Howmet Aerospace Inc.
Summary of significant accounting policies
Concentration risk		10.00%	11.00%
Customer \| Sales Revenue \| Howmet Aerospace Inc. \| Specialty Alloys Operations
Summary of significant accounting policies
Concentration risk		90.00%
Customer \| Sales Revenue \| Howmet Aerospace Inc. \| Performance Engineered Products
Summary of significant accounting policies
Concentration risk		10.00%
Minimum \| Capitalized software
Summary of significant accounting policies
Estimated useful life	3 years
Minimum \| Intangible Assets
Summary of significant accounting policies
Estimated useful life	5 years
Maximum \| Capitalized software
Summary of significant accounting policies
Estimated useful life	12 years
Maximum \| Intangible Assets
Summary of significant accounting policies
Estimated useful life	30 years