Fair Value Measurements (Details 2) (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2011 positions Y D month MMbtu segment	Dec. 31, 2010
Assets and liabilities measured at fair value on a recurring basis
Cash and cash equivalents	$ 1,426.1	$ 797.7
Asset retirement obligation funds	95.0	95.0
Investments in auction rate securities	71.1	102.8
Cash and cash equivalents, maximum maturity period	three months	three months
Short-term investments, original maturity period		twelve months
Auction rate securities interest rate reset period, low end of range (in days)	7
Auction rate securities interest rate reset period, high end of range (in days)	35
Auction rate securities sold or redeemed at par	9.2
Maximum maturity period of auction rate securities (in years)	36
Recurring basis \| Quoted Prices in Active Markets (Level 1)
Assets and liabilities measured at fair value on a recurring basis
Cash and cash equivalents	1,426.1	797.7
Available-for-sale short-term investments		3.1
Asset retirement obligation funds	95.0	95.0
Nonqualified employee benefit trusts	21.2	20.9
Total assets at fair value	1,542.3	916.7
Recurring basis \| Significant Other Observable Inputs (Level 2)
Assets and liabilities measured at fair value on a recurring basis
Unrealized gains on natural gas derivatives		6.6
Total assets at fair value		6.6
Unrealized losses on natural gas derivatives	24.5	3.5
Total liabilities at fair value	24.5	3.5
Recurring basis \| Significant Unobservable Inputs (Level 3)
Assets and liabilities measured at fair value on a recurring basis
Investments in auction rate securities	71.1	102.8
Total assets at fair value	71.1	102.8
Recurring basis \| Total Fair Value
Assets and liabilities measured at fair value on a recurring basis
Cash and cash equivalents	1,426.1	797.7
Available-for-sale short-term investments		3.1
Unrealized gains on natural gas derivatives		6.6
Asset retirement obligation funds	95.0	95.0
Investments in auction rate securities	71.1	102.8
Nonqualified employee benefit trusts	21.2	20.9
Total assets at fair value	1,613.4	1,026.1
Unrealized losses on natural gas derivatives	24.5	3.5
Total liabilities at fair value	$ 24.5	$ 3.5

Total amount held in an escrow account related to asset retirement obligation.

Name:	cf_AssetRetirementObligationEscrowAccount
Namespace Prefix:	cf
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the high end of the range of the interest rate reset period through the auction process of auction rate securities.

+ Details

Name:	cf_AuctionRateSecuritiesInterestRateResetPeriodHighEndOfRange
Namespace Prefix:	cf
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the low end of the range of the interest rate reset period through the auction process of auction rate securities.

+ Details

Name:	cf_AuctionRateSecuritiesInterestRateResetPeriodLowEndOfRange
Namespace Prefix:	cf
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The maximum maturity period of auction rate securities.

+ Details

Name:	cf_AuctionRateSecuritiesMaturityPeriodHighEndOfRange
Namespace Prefix:	cf
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the maximum maturity period of cash and cash equivalents.

+ Details

Name:	cf_CashAndCashEquivalentsMaximumMaturityPeriod
Namespace Prefix:	cf
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	instant

- Definition

Total amount of investments in auction rate securities.

+ Details

Name:	cf_InvestmentsInAuctionRateSecurities
Namespace Prefix:	cf
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the nonqualified employee benefit trusts measured at fair value.

+ Details

Name:	cf_NonqualifiedEmployeeBenefitTrustsFairValueDisclosure
Namespace Prefix:	cf
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the original maturity period of short-term investments.

+ Details

Name:	cf_ShortTermInvestmentsOriginalMaturityPeriod
Namespace Prefix:	cf
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	instant

- Definition

This element represents the aggregate of the assets reported on the balance sheet at period end measured at fair value by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

+ Details

Name:	us-gaap_AssetsFairValueDisclosure
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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 Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 12

-Subparagraph b

-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 2: 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=6379932&loc=d3e22054-111558

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Available-for-Sale Securities

-URI http://asc.fasb.org/extlink&oid=6505594

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesFairValueDisclosure
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The aggregate value of securities held, which were categorized neither as trading nor held-to-maturity, for which the interest rate reset through an auction process, that failed to be liquidated through auction, and which were sold at par value during the period.

+ Details

Name:	us-gaap_AvailableforsaleSecuritiesSoldAtPar
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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 includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the Company may deposit additional funds at any time and also effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Cash

-URI http://asc.fasb.org/extlink&oid=6506951

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Cash Equivalents

-URI http://asc.fasb.org/extlink&oid=6507016

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 7, 8, 9, 10

-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 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 7

-Footnote 1

-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 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 8

-Footnote 2

-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.

+ Details

Name:	us-gaap_CashAndCashEquivalentsFairValueDisclosure
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.

+ Details

Name:	us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems
Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the aggregate of the liabilities reported on the balance sheet at period end measured at fair value by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

+ Details

Name:	us-gaap_LiabilitiesFairValueDisclosure
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value as of the balance sheet date of price risk derivative assets, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as assets on the balance sheet.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 17

-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 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13433-108611

+ Details

Name:	us-gaap_PriceRiskDerivativeAssetsAtFairValue
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value as of the balance sheet date of price risk derivative liabilities, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as liabilities on the balance sheet.

+ References

+ Details

Name:	us-gaap_PriceRiskDerivativeLiabilitiesAtFairValue
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant