Represents the number of anniversaries of grant date on which share-based compensation awards vest.

No definition available.

Name:	cmd_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingOnNumberOfAnniversariesOfGrantDate
Namespace Prefix:	cmd_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of shares authorized for issuance under share-based payment arrangement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of options outstanding, including both vested and non-vested options.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of vesting of award under share-based payment arrangement.

+ References

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_AwardTypeAxis=cmd_EmployeeAndDirectorsStockOptionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=cmd_EquityIncentivePlan2006Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=cmd_StockOptionsAndStockAppreciationRightsSARSMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=cmd_RestrictedStockAndOtherStockAwardsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VestingAxis=us-gaap_ShareBasedCompensationAwardTrancheOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VestingAxis=us-gaap_ShareBasedCompensationAwardTrancheTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VestingAxis=us-gaap_ShareBasedCompensationAwardTrancheThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Stock-Based Compensation - 2006 Plan (Details)	12 Months Ended
Stock-Based Compensation - 2006 Plan (Details)	Jul. 31, 2020 Installment shares	Jul. 31, 2019 shares	Jul. 31, 2018 shares	Jul. 31, 2017 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding unvested restricted stock shares	411,715,000	307,153,000	212,106,000	222,298,000
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding options (in shares)	15,000	40,000	70,000
2006 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of shares authorized for issuance	5,591,000
2006 Plan \| Stock options and stock appreciation rights
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of shares authorized for issuance	2,700,000
2006 Plan \| Restricted stock and other stock awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of shares authorized for issuance	2,891,000
2006 Plan \| Restricted shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of anniversaries of grant date on which awards vest \| Installment	3
Outstanding unvested restricted stock shares	0
2006 Plan \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding options (in shares)	15,000
First anniversary vesting \| 2006 Plan \| Restricted shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	33.33%
Vesting period	1 year
Second anniversary vesting \| 2006 Plan \| Restricted shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	33.33%
Vesting period	2 years
Third anniversary vesting \| 2006 Plan \| Restricted shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	33.33%
Vesting period	3 years