Common stock reserved for issuance under the Company's ESPP.

No definition available.

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Balance Type:	na
Period Type:	instant

- Definition

Employer matching contribution, percentage.

+ References

No definition available.

+ Details

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Namespace Prefix:	cmg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Deferred compensation arrangement with individual, employer matching contribution percent

+ References

No definition available.

+ Details

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Namespace Prefix:	cmg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The maximum percent an employee may contribute after one year of service with the Company.

+ References

No definition available.

+ Details

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Namespace Prefix:	cmg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Eligibility period to contribute to the ESPP.

+ References

No definition available.

+ Details

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Namespace Prefix:	cmg_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Eligibility period to receive matching contributions

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

The compensation expense recognized during the period pertaining to the deferred compensation arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 12

-Paragraph 6, 7

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (b)

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-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph 64, 65

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 710

-SubTopic 10

-Section 30

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6409875&loc=d3e20015-108363

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of payment into the fund established for purposes of making future disbursements to the individual in accordance with the terms and understanding of the deferred compensation arrangement.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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- Details

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Period Type:	duration

- Definition

Aggregate carrying value as of the balance sheet date of the liabilities for all deferred compensation arrangements. Represents currently earned compensation under compensation arrangements that is not actually paid until a later date.

+ References

No definition available.

+ Details

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

- Definition

The amount of the cost recognized during the period for defined contribution plans.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 70

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6414718&loc=d3e28014-114942

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 11

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

+ References

No definition available.

+ Details

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

- Definition

Number of shares issued during the period as a result of an employee stock purchase plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 5

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 12

-Paragraph 10

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30

-Article 5

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

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- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Trading Securities which consist of all investments in certain debt and equity securities that are bought and held principally for the purpose of selling them in the near term (thus held for only a short period of time) or for which an entity has elected the fair value option. Trading generally reflects active and frequent buying and selling, and trading securities are generally used with the objective of generating profits on short-term differences in price, but this category of investments may also include items which are not intended to be sold in the near term or for which the fair value option has been elected.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-Subparagraph (a)

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 12

-Subparagraph a

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Trading Securities

-URI http://asc.fasb.org/extlink&oid=6526789

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- Definition

The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of trading securities held at each balance sheet date, that was included in earnings for the period. Trading securities are bought and held principally for the purpose of selling them in the near term (thus held for only a short period of time) and the change in net unrealized holding gain (loss) is included in earnings for the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Trading Securities

-URI http://asc.fasb.org/extlink&oid=6526789

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 21

-Subparagraph e

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 13

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

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-Name Statement of Financial Accounting Standard (FAS)

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.7(c))

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-Name Accounting Standards Codification

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-SubTopic 10

-Section 35

-Paragraph 1

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=16383099&loc=d3e24584-111560

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Employee Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Period of service before an employee is eligible for contribution	1 year
Common stock authorized and reserved for ESPP	250
ESPP employee contribution, percentage	15.00%
Shares issued under ESPP	1
Fair value of investments in rabbi trust	$ 10,037
Unrealized gains on investments held in rabbi trust	240
401(k) Plan [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Period of service before an employee is eligible for contribution	1 year
Company matching contributions	2,431	2,039	1,734
Deferred Plan [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Total liabilities under Deferred Plan	10,037	6,802
Deferred compensation matching contributions	213	179	156
Deferred compensation expense	$ 487	$ 20	$ 610
First 3% [Member] \| 401(k) Plan [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Employer matching contribution, percentage	100.00%
Percentage of employees' gross pay for which the employer contributes a matching contribution	3.00%
First 3% [Member] \| Deferred Plan [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Employer matching contribution, percentage	100.00%
Percentage of employees' gross pay for which the employer contributes a matching contribution under the Deferred Plan	3.00%
Next 2% [Member] \| 401(k) Plan [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Employer matching contribution, percentage	50.00%
Percentage of employees' gross pay for which the employer contributes a matching contribution	2.00%
Next 2% [Member] \| Deferred Plan [Member]
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Employer matching contribution, percentage	50.00%
Percentage of employees' gross pay for which the employer contributes a matching contribution under the Deferred Plan	2.00%