Investment Securities (Schedule Of Investment Securities) (Details) - USD ($) $ in Thousands	Feb. 25, 2017	May 28, 2016
Current Assets
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 157,619	$ 360,400
Unrealized Gains	79	170
Unrealized Losses	28	71
Estimated Fair Value	157,670	360,499
Noncurrent Assets
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,751	1,448
Unrealized Gains	736	489
Unrealized Losses	0	0
Estimated Fair Value	2,487	1,937
US government and agency obligations
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	17,062
US government and agency obligations \| Current Assets
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	17,089	18,809
Unrealized Gains	0	5
Unrealized Losses	27	0
Estimated Fair Value	17,062	18,814
Municipal bonds \| Current Assets
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	46,981	79,481
Unrealized Gains	30	162
Unrealized Losses	0	0
Estimated Fair Value	47,011	79,643
Corporate bonds \| Current Assets
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	85,703	240,593
Unrealized Gains	49	0
Unrealized Losses	0	56
Estimated Fair Value	85,752	240,537
Foreign government obligations \| Current Assets
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,009	2,044
Unrealized Gains	0	2
Unrealized Losses	1	0
Estimated Fair Value	2,008	2,046
Asset backed securities \| Current Assets
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	5,837	15,908
Unrealized Gains	0	0
Unrealized Losses	0	15
Estimated Fair Value	5,837	15,893
Mutual funds \| Current Assets
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		3,565
Unrealized Gains		1
Unrealized Losses		0
Estimated Fair Value		3,566
Mutual funds \| Noncurrent Assets
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,751	1,448
Unrealized Gains	736	489
Unrealized Losses	0	0
Estimated Fair Value	$ 2,487	$ 1,937

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=51813488&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=49167202&loc=d3e26610-111562

+ Details

Name:	us-gaap_AvailableForSaleSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

+ Details

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

- Definition

Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.2)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesAmortizedCost
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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_ScheduleOfAvailableForSaleSecuritiesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_BalanceSheetLocationAxis=calm_CurrentAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BalanceSheetLocationAxis=calm_NoncurrentAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_USGovernmentDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_MunicipalBondsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_ForeignGovernmentDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=calm_MutualFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: