The Mosaic Company (MOS) 10-K 17 Feb 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
In Billions, except Share data, unless otherwise specified	Dec. 31, 2014	Jun. 30, 2014	Feb. 11, 2015
Entity registrant name	MOSAIC CO
Trading Symbol	MOS
Document type	10-K
Entity central index key	1285785
Amendment flag	FALSE
Entity current reporting status	Yes
Entity voluntary filers	No
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Document period end date	31-Dec-14
Current fiscal year end date	-19
Entity filer category	Large Accelerated Filer
Entity well known seasoned issuer	Yes
Entity public float		$18
Common Class A [Member]
Entity common stock shares outstanding			17,176,046
Common Class B [Member]
Entity common stock shares outstanding			0
No Class Common Stock [Member]
Entity common stock shares outstanding			348,667,983

Consolidated_Statements_of_Ear

Consolidated Statements of Earnings (USD $)	7 Months Ended	12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014	31-May-13	31-May-12
Consolidated Statement of Earnings
Net sales	$4,765.90	$9,055.80	$9,974.10	$11,107.80
Cost of goods sold	3,937.60	7,129.20	7,213.90	8,022.80
Gross margin	828.3	1,926.60	2,760.20	3,085
Selling, general and administrative expenses	211.8	382.4	427.3	410.1
(Gain) loss on assets sold and to be sold	122.8	-16.4	0	0
Carlsbad restructuring expense	0	125.4	0	0
Other operating expenses	76.8	123.4	123.3	63.8
Operating earnings	416.9	1,311.80	2,209.60	2,611.10
(Loss) gain in value of share repurchase agreement	73.2	-60.2	0	0
Interest (expense) income, net	-13.3	-107.6	18.8	18.7
Foreign currency transaction gain (loss)	16.5	79.1	-15.9	16.9
Other (expense) income	-9.1	-5.8	2	-17.8
Earnings from consolidated companies before income taxes	484.2	1,217.30	2,214.50	2,628.90
Provision for income taxes	152.6	184.7	341	711.4
Earnings from consolidated companies	331.6	1,032.60	1,873.50	1,917.50
Equity in net earnings (loss) of nonconsolidated companies	10.9	-2.2	18.3	13.3
Net earnings including noncontrolling interests	342.5	1,030.40	1,891.80	1,930.80
Less: Net earnings attributable to noncontrolling interests	2.5	1.8	3.1	0.6
Net earnings attributable to Mosaic	$340	$1,028.60	$1,888.70	$1,930.20
Basic net earnings per share attributable to Mosaic (in usd per share)	$0.80	$2.69	$4.44	$4.44
Basic weighted average number of shares outstanding (in shares)	420.8	374.1	425.7	435.2
Diluted net earnings per share attributable to Mosaic (in usd per share)	$0.80	$2.68	$4.42	$4.42
Diluted weighted average number of shares outstanding (in shares)	422	375.6	426.9	436.5

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	7 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014	31-May-13	31-May-12
Statement of Comprehensive Income [Abstract]
Net earnings including noncontrolling interest	$342.50	$1,030.40	$1,891.80	$1,930.80
Other comprehensive income (loss), net of tax
Foreign currency translation, net of tax of $87.0, $34.1, ($16.0), and $28.0, respectively	-226.8	-560.8	-46.6	-307.4
Net actuarial gain (loss) and prior service cost, net of tax of $20.5, $20.9, $5.7, and $14.6, respectively	34.5	-38.2	-5.7	-28.7
Realized gain (loss) on interest rate swap, net of tax of $6.3	-21.1	9	0	0
Other comprehensive income (loss)	-213.4	-590	-52.3	-336.1
Comprehensive income	129.1	440.4	1,839.50	1,594.70
Less: Comprehensive income (loss) attributable to noncontrolling interest	1.2	-0.2	2.4	-3.3
Comprehensive income attributable to Mosaic	$127.90	$440.60	$1,837.10	$1,598

Consolidated_Statements_of_Com1

Consolidated Statements of Comprehensive Income (Parentheticals) (USD $)	7 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014	31-May-13	31-May-12
Other Comprehensive Income (Loss), Tax, Parenthetical Disclosures [Abstract]
Foreign currency translation, tax	$34.10	$87	($16)	$28
Net actuarial gain (loss), tax	20.9	20.5	5.7	14.6
Realized gain (loss) on interest rate swap, tax		$6.30

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$2,374,600,000	$5,293,100,000
Receivables, net	754,400,000	543,100,000
Inventories	1,718,300,000	1,432,900,000
Deferred income taxes	148,700,000	129,900,000
Other current assets	368,200,000	706,800,000
Total current assets	5,364,200,000	8,105,800,000
Property, plant and equipment, net	9,313,900,000	8,576,600,000
Investments in nonconsolidated companies	849,800,000	576,400,000
Goodwill	1,806,500,000	1,794,400,000
Deferred income taxes	394,400,000	152,200,000
Other assets	554,200,000	348,600,000
Total assets	18,283,000,000	19,554,000,000
Current liabilities:
Short-term debt	13,500,000	22,600,000
Current maturities of long-term debt	41,000,000	400,000
Accounts payable	797,300,000	570,200,000
Accrued liabilities	726,100,000	666,300,000
Contractual share repurchase liability	0	1,985,900,000
Deferred income taxes	3,700,000	20,500,000
Accrued income taxes	18,800,000	0
Total current liabilities	1,600,400,000	3,265,900,000
Long-term debt, less current maturities	3,778,000,000	3,008,900,000
Deferred income taxes	984,000,000	1,031,500,000
Other noncurrent liabilities	1,200,000,000	927,100,000
Equity:
Preferred stock, par value	0	0
Capital in excess of par value	4,200,000	1,600,000
Retained earnings	11,168,900,000	11,182,100,000
Accumulated other comprehensive income (loss)	-473,700,000	114,300,000
Total Mosaic stockholders’ equity	10,703,100,000	11,302,300,000
Non-controlling interests	17,500,000	18,300,000
Total equity	10,720,600,000	11,320,600,000
Total liabilities and equity	18,283,000,000	19,554,000,000
Common Class A [Member]
Equity:
Common stock, value	200,000	1,300,000
Common Class B [Member]
Equity:
Common stock, value	0	0
No Class Common Stock [Member]
Equity:
Common stock, value	$3,500,000	$3,000,000

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parentheticals) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Preferred stock, par value (in usd per share)	$0.01	$0.01
Preferred stock, authorized (in shares)	15,000,000	15,000,000
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Common Class A [Member]
Common stock, par value (in usd per share)	$0.01	$0.01
Common stock, authorized (in shares)	194,203,987	254,300,000
Common stock, issued (in shares)	17,176,046	128,759,772
Common stock, outstanding (in shares)	17,176,046	85,839,827
Common Class B [Member]
Common stock, par value (in usd per share)	$0.01	$0.01
Common stock, authorized (in shares)	87,008,602	87,008,602
Common stock, issued (in shares)	0	0
Common stock, outstanding (in shares)	0	0
No Class Common Stock [Member]
Common stock, par value (in usd per share)	$0.01	$0.01
Common stock, authorized (in shares)	1,000,000,000	1,000,000,000
Common stock, issued (in shares)	369,987,783	352,204,571
Common stock, outstanding (in shares)	350,364,236	340,166,109

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	7 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014	31-May-13	31-May-12
Cash Flows from Operating Activities
Net earnings including noncontrolling interest	$342.50	$1,030.40	$1,891.80	$1,930.80
Depreciation, depletion and amortization	386.2	750.9	604.8	508.1
Deferred income taxes	69.1	-153.8	200	245.8
Equity in net loss (earnings) of nonconsolidated companies, net of dividends	3.9	4.7	32.2	-3.7
Accretion expense for asset retirement obligations	21.6	42.1	33.3	32.4
Share-based compensation expense	23.3	54.3	28.2	23.4
Amortization of acquired inventory	0	49	0	0
Change in value of share repurchase agreement	-73.2	60.2	0	0
(Gain) loss on assets sold and to be sold	122.8	-16.4	0	0
Unrealized loss (gain) on derivatives	-15.4	34.8	-1.4	45.9
Carlsbad restructuring expense	0	125.4	0	0
Other	43.7	10.9	30.5	31.5
Changes in assets and liabilities, net of acquisitions:
Receivables, net	404.1	-226.5	-296.7	118.5
Inventories, net	30.8	-129.7	-315.5	6.5
Other current assets and noncurrent assets	-101	457.7	-2.7	-238.8
Accounts payable	-100.6	277.2	-100.5	-58.4
Accrued liabilities	-223.5	30.4	-55.7	-2.2
Other noncurrent liabilities	-44.9	-107.9	-160.8	66
Net cash provided by operating activities	889.4	2,293.70	1,887.50	2,705.80
Cash Flows from Investing Activities
Capital expenditures	-800	-929.1	-1,588.30	-1,639.30
Proceeds from sale of businesses	0	81.4	0	0
Acquisition of businesses	0	-1,725.40	0	0
Investments in nonconsolidated companies	-158.9	-154.6	-15	0
Other	1.7	-11.4	13.5	11.9
Net cash (used in) investing activities	-957.2	-2,739.10	-1,589.80	-1,627.40
Cash Flows from Financing Activities
Payments of short-term debt	-154.3	-220.4	-263.1	-148.8
Proceeds from issuance of short-term debt	119.1	200.2	289.1	167.9
Payments of long-term debt	-1.4	-2.1	-1.5	-542.8
Proceeds from issuance of long-term debt	2,000.30	812	1.9	748
Payment of tender premium on debt	0	0	0	-17.2
Payment of financing costs	-21.7	0	0	0
Realized loss on interest rate swap	-21.1	0	0	0
Contributions by Cargill	0	0	0	18.5
Repurchase of stock	0	-2,755.30	0	-1,162.50
Cash dividends paid	-213.5	-382.5	-426.6	-119.5
Other	-2.1	8.1	2.4	-4.7
Net cash provided by (used in) financing activities	1,705.30	-2,340	-397.8	-1,061.10
Effect of exchange rate changes on cash	-41.5	-133.1	-13.8	-112.7
Net change in cash and cash equivalents	1,596	-2,918.50	-113.9	-95.4
Cash and cash equivalents - beginning of period	3,697.10	5,293.10	3,811	3,906.40
Cash and cash equivalents - end of period	$5,293.10	$2,374.60	$3,697.10	$3,811

Consolidated_Statements_of_Sha

Consolidated Statements of Shareholders Equity (USD $)	Total	Common Stock [Member]	Capital in Excess of Par Value [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Non- Controlling Interests [Member]
In Millions, except Share data, unless otherwise specified
Beginning balance at May. 31, 2011	$11,661.90	$4.50	$2,596.30	$8,330.60	$710.20	$20.30
Common stock shares outstanding, beginning balance (in shares) at May. 31, 2011		446,600,000
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Total comprehensive income (loss)	1,594.70			1,930.20	-332.2	-3.3
Stock option exercises /Restricted stocks units vested	3		3
Stock option exercises /Restricted stocks units vested (in shares)		200,000
Amortization of stock based compensation	23.4		23.4
Repurchase of Class A common stock	-1,162.50	-0.2	-1,162.30
Repurchase of Class A common stock (in shares)		-21,300,000
Dividends	-119.5			-119.5
Dividends for noncontrolling interests	-0.7					-0.7
Tax benefits (shortfall) related to share based compensation	-0.9		-0.9
Ending balance at May. 31, 2012	11,999.40	4.3	1,459.50	10,141.30	378	16.3
Common stock shares outstanding, ending balance (in shares) at May. 31, 2012		425,500,000
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Total comprehensive income (loss)	1,839.50			1,888.70	-51.6	2.4
Stock option exercises	6		6
Stock option exercises (in shares)		300,000
Amortization of stock based compensation	28.2		28.2
Dividends	-426.6			-426.6
Dividends for noncontrolling interests	-1.2					-1.2
Tax benefits (shortfall) related to share based compensation	-2.4		-2.4
Ending balance at May. 31, 2013	13,442.90	4.3	1,491.30	11,603.40	326.4	17.5
Common stock shares outstanding, ending balance (in shares) at May. 31, 2013		425,800,000
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Total comprehensive income (loss)	129.1			340	-212.1	1.2
Stock option exercises	1.1		1.1
Stock option exercises (in shares)		100,000
Amortization of stock based compensation	23.3		23.3
Forward contract and other repurchases of stock	-2,059.10		-1,511.30	-547.8
Dividends	-213.5			-213.5
Dividends for noncontrolling interests	-0.4					-0.4
Tax benefits (shortfall) related to share based compensation	-2.8		-2.8
Ending balance at Dec. 31, 2013	11,320.60	4.3	1.6	11,182.10	114.3	18.3
Common stock shares outstanding, ending balance (in shares) at Dec. 31, 2013		425,900,000
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Total comprehensive income (loss)	440.4			1,028.60	-588	-0.2
Stock option exercises	6.7		6.7
Stock option exercises (in shares)		700,000
Amortization of stock based compensation	54.3		54.3
Forward contract and other repurchases of stock	-720.3	-0.6	-60.4	-659.3
Forward contract and other repurchases of stock (in shares)		-59,100,000
Dividends	-382.5			-382.5
Dividends for noncontrolling interests	-0.6					-0.6
Tax benefits (shortfall) related to share based compensation	2		2
Ending balance at Dec. 31, 2014	$10,720.60	$3.70	$4.20	$11,168.90	($473.70)	$17.50
Common stock shares outstanding, ending balance (in shares) at Dec. 31, 2014		367,500,000

Consolidated_Statements_of_Sha1

Consolidated Statements of Shareholders Equity (Parentheticals) (USD $)	7 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2014	31-May-13	31-May-12
Statement of Stockholders' Equity [Abstract]
Dividends per share (in usd per share)	$0.50	$1	$1	$0.28

Organization_and_Nature_of_Bus

Organization and Nature of Business	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Nature of Business	ORGANIZATION AND NATURE OF BUSINESS
	The Mosaic Company (before or after the Cargill Transaction described in Note 2, “Mosaic”, and with its consolidated subsidiaries, “we”, “us”, “our”, or the “Company”) is the parent company of the business that was formed through the business combination (“Combination”) of IMC Global Inc. and the Cargill Crop Nutrition fertilizer businesses of Cargill, Incorporated and its subsidiaries (collectively, “Cargill”) on October 22, 2004.
	We produce and market concentrated phosphate and potash crop nutrients. We conduct our business through wholly and majority owned subsidiaries as well as businesses in which we own less than a majority or a non-controlling interest, including consolidated variable interest entities and investments accounted for by the equity method. We are organized into the following business segments:
	Our Phosphates business segment owns and operates mines and production facilities in Florida which produce concentrated phosphate crop nutrients and phosphate-based animal feed ingredients, and processing plants in Louisiana which produce concentrated phosphate crop nutrients. Our Phosphates segment's results also include our international distribution activities. In fiscal 2011, the Phosphates segment acquired a 35% economic interest in a joint venture that owns the Miski Mayo Mine in Peru. On August 5, 2013, we entered into a Shareholders’ Agreement with Saudi Arabian Mining Company (“Ma’aden”) and Saudi Basic Industries Corporation (“SABIC”) under which the parties have formed Wa'ad Al Shamal Phosphate Company (the “Wa’ad Al Shamal Joint Venture”) to develop, own and operate integrated phosphate production facilities in the Kingdom of Saudi Arabia . We own 25% of the joint venture and will market approximately 25% of the production of the joint venture. On March 17, 2014, we completed the acquisition of the Florida phosphate assets and assumption of certain related liabilities ("CF Phosphate Assets Acquisition") of CF Industries, Inc. ("CF"). On December 17, 2014, we completed the acquisition of Archer Daniels Midland Company's ("ADM's") fertilizer distribution business in Brazil and Paraguay. These transactions are further described in Note 23 of our Notes to Consolidated Financial Statements.
	Our Potash business segment owns and operates potash mines and production facilities in Canada and the U.S. which produce potash-based crop nutrients, animal feed ingredients and industrial products. Potash sales include domestic and international sales. We are a member of Canpotex, Limited (“Canpotex”), an export association of Canadian potash producers through which we sell our Canadian potash outside the U.S. and Canada.
	Intersegment sales are eliminated within Corporate, Eliminations and Other. See Note 24 of our Notes to Consolidated Financial Statements for segment results.
	As previously reported, we changed our fiscal year end to December 31 from May 31 in 2013.

Cargill_Transaction

Cargill Transaction	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Cargill Transaction	CARGILL TRANSACTION
	On May 25, 2011, we consummated the first in a series of transactions intended to result in the split-off and orderly distribution of Cargill’s approximately 64% equity interest in us through a series of transactions (the “Cargill Transaction”). These transactions included the following:
	•	A Merger (the “Merger”) between a subsidiary of GNS II (U.S.) Corp. (“GNS”) and MOS Holdings Inc. (“MOS Holdings”) that had the effect of recapitalizing our prior Common Stock into three classes: Common Stock, Class A Common Stock (“Class A Shares”) and Class B Common Stock (“Class B Shares”). The Common Stock is substantially identical to our prior Common Stock, and all three new classes had the same economic rights as our prior Common Stock. Holders of the Common Stock and the Class A Shares have one vote per share on all matters on which they are entitled to vote, whereas holders of the Class B Shares had ten votes per share solely for the election of directors and one vote per share on all other matters on which they were entitled to vote. The Class A Shares are and the Class B Shares were subject to transfer restrictions, have or had conversion rights and class voting rights, and are or were not publicly traded. Following the Merger, our Common Stock continues to trade under the ticker symbol MOS.
	•	Prior to the Merger, GNS was a wholly-owned subsidiary of the company then known as The Mosaic Company. The Merger made GNS the parent company of MOS Holdings. In connection with the Merger, the company formerly known as The Mosaic Company was renamed MOS Holdings Inc. and GNS was renamed The Mosaic Company.
	•	In the Merger, a portion of our Common Stock held by Cargill was converted, on a one-for-one basis, into the right to receive Class A Shares and Class B Shares. Each other outstanding share of our prior Common Stock (including a portion of the shares of our prior Common Stock held by Cargill) was converted into the right to receive a share of our Common Stock.
	•	Cargill conducted a split-off (the “Split-off”) in which it exchanged 178.3 million of our shares that it received in the Merger for shares of Cargill stock held by certain Cargill stockholders (the “Exchanging Cargill Stockholders”). Immediately after the Split-off, the Exchanging Cargill Stockholders held approximately 40% of our total outstanding shares that represented approximately 82% of the total voting power with respect to the election of our directors.
	•	Cargill also exchanged the remaining 107.5 million of our shares that it received in the Merger with certain holders of Cargill debt (the “Exchanging Cargill Debt Holders”) for such Cargill debt (the “Debt Exchange”).
	•	Certain of the Exchanging Cargill Stockholders (the “MAC Trusts”) and the Exchanging Cargill Debt Holders (collectively, the “Selling Stockholders”) then sold an aggregate of 115.0 million shares of our Common Stock that they received in the Split-off and the Debt Exchange in an underwritten secondary public offering (the “Formation Offering”).
	•	All other shares of our stock (approximately 128.8 million Class A Shares in the aggregate) received by the Exchanging Cargill Stockholders and not sold in the Formation Offering have generally been subject to transfer restrictions and were to be released in three equal annual installments beginning on November 26, 2013, unless sold prior to the release date.
	Pursuant to a ruling from the U.S. Internal Revenue Service, the Merger, Split-off and Debt Exchange were tax-free to Cargill, Mosaic and their respective stockholders.
	Subsequently, we have completed several additional transactions in furtherance of the Cargill Transaction:
	•	On September 29, 2011, we converted 20.7 million Class A Shares, Series A-4, to Common Stock in connection with their sale in an underwritten public secondary offering by the MAC Trusts. In accordance with our Restated Certificate of Incorporation, each such converted Class A Share was subsequently retired and cancelled and may not be reissued, and the number of authorized Class A Shares was reduced by a corresponding amount.
	•	On October 6, 2011, our stockholders approved the conversion of each of our approximately 113.0 million outstanding Class B Shares on a one-for-one basis into shares of the corresponding series of Class A Shares. In accordance with our Restated Certificate of Incorporation, each such converted Class B Share was subsequently retired and cancelled and may not be reissued, and the number of authorized Class B Shares was reduced by a corresponding amount.
	•	On November 17, 2011, we purchased an aggregate 21.3 million Class A Shares, Series A-4, from the MAC Trusts. The purchase price was $54.58 per share, the closing price for our Common Stock on November 16, 2011, resulting in a total purchase price of approximately $1.2 billion. This repurchase completed the disposition of the 157.0 million shares designated to be sold during the 15-month period following the Split-off by the Selling Stockholders.
	•	On November 26, 2013, pursuant to the terms of our Restated Certificate of Incorporation, all 42.9 million outstanding Class A Shares, Series A-1(including 21,647,007 shares held by the MAC Trusts), were converted into regular Mosaic Common Stock, par value $.01 per share. On November 26, 2014, the remaining 17,176,068 Class A Shares, Series A-
	2, held by Exchanging Cargill Stockholders, were converted into Common Stock. In accordance with our Restated Certificate of Incorporation, each such converted Class A Share was subsequently retired and cancelled and may not be reissued, and the number of authorized Class A Shares was reduced by a corresponding amount. Conversion of the remaining 17,176,046 Class A Shares, Series A-3, held by Exchanging Cargill Stockholders, is scheduled to occur on November 26, 2015.
	•	In addition, on November 26, 2013, the last of the restrictions imposed by the agreements relating to the Cargill Transaction on our ability to engage in share buybacks expired. On December 6, 2013, Mosaic entered into a share repurchase agreement (the “MAC Trusts Share Repurchase Agreement”) with the MAC Trusts to purchase all of the remaining Class A Shares held by the MAC Trusts. During 2014, pursuant to the MAC Trusts Share Repurchase Agreement, all 21,647,007 Class A Shares, Series A-3 and all 21,647,008 Class A Shares, Series A-2, held by the MAC Trusts, were repurchased for an aggregate of $2.0 billion.
	Under the MAC Trusts Share Repurchase Agreement, the purchase price per share was equal to the Common Market Price, as defined in Mosaic’s Restated Certificate of Incorporation, as of the date of the purchase. In general and subject to the terms and provisions of the Restated Certificate of Incorporation, the Common Market Price as of any date is equal to the average of the volume weighted average trading price of Common Stock, for each trading day during the preceding 20-day trading period.
	In addition to the Class A Shares purchased by Mosaic under the MAC Trusts Share Repurchase Agreement, the MAC Trusts received an aggregate of 21,647,007 shares of Common Stock that were converted from outstanding Class A Shares, Series A-1, on November 26, 2013. Based solely on a Schedule 13G/A dated December 31, 2014 and filed with the Securities and Exchange Commission on January 13, 2015 by Christine M. Morse and Paul G. Busch, the MAC Trusts beneficially own less than five percent of our outstanding shares of Common Stock.
	In February of 2014, our Board of Directors authorized a $1 billion share repurchase program (the “Repurchase Program”), allowing the Company to repurchase Class A Shares or shares of our Common Stock, through direct buybacks or in open market transactions. This authorization is in addition to the MAC Trusts Share Repurchase Agreement described above. During 2014, under the Repurchase Program, 8,193,698 Class A Shares were repurchased under agreements we entered with certain Cargill family member trusts (the “Family Trusts Share Repurchase Agreements”, and together with the MAC Trusts Share Repurchase Agreement, the "Share Repurchase Agreements") and 7,585,085 shares of Common Stock were repurchased in the open market for an aggregate of $727.3 million.
	The Share Repurchase Agreements were accounted for as forward contracts with an initial liability established at fair value based on the average of the weighted average trading price for each of the preceding 20 trading days as noted above and a corresponding reduction of equity. The contracts were subsequently remeasured at the present value of the amount to be paid at settlement with the difference being recognized in the consolidated statement of earnings. In calculating basic and diluted earnings per share (“EPS”), we were required to exclude the Class A shares that remained to be repurchased. Any amounts, including contractual (accumulated) dividends and participation rights in undistributed earnings, attributable to shares that remained to be repurchased that had not yet been recognized in the consolidated statement of earnings were deducted in computing income available to common shareholders, consistent with the two-class method. See the calculation of EPS in Note 7 of our Notes to Consolidated Financial Statements.
	As part of the Cargill Transaction, we agreed that, among other things, and subject to certain exceptions:
	•	We would not engage in certain prohibited acts (“Prohibited Acts”) until May 26, 2013.
	•	We are contractually obligated to indemnify Cargill for certain taxes and tax-related losses imposed on Cargill if we engaged in a Prohibited Act or in the event we are in breach of representations or warranties made in support of the tax-free nature of the Merger, Split-off and Debt Exchange, if our Prohibited Act or breach causes the Merger, Split-off and/or Debt Exchange to fail to qualify as tax-free transactions.
	Generally speaking, Prohibited Acts included:
	•	Entering into any agreements, understandings, arrangements or substantial negotiations pursuant to which any person would acquire, increase or have the right to acquire or increase such person’s ownership interest in us, provided that equity issuances, redemptions or repurchases from the MAC Trusts and approvals of transfers within an agreed-upon “basket” were not Prohibited Acts.
	•	Approving or recommending a third-party tender offer or exchange offer for our stock or causing or permitting any merger, reorganization, combination or consolidation of Mosaic or MOS Holdings.
	•	Causing our “separate affiliated group” (as defined in the Internal Revenue Code) to fail to be engaged in the fertilizer business.
	•	Reclassifying, exchanging or converting any shares of our stock into another class or series, or changing the voting rights of any shares of our stock (other than the conversion of Class B Common Stock to Class A Common Stock) or declaring or paying a stock dividend in respect of our common stock.
	•	Facilitating the acquisition of Mosaic’s stock by any person or coordinating group (as defined in IRS regulations) (other than Cargill and its subsidiaries), if such acquisition would result in any person or coordinating group beneficially owning 10% or more of our outstanding Common Stock.
	•	Facilitating participation in management or operation of the Company (including by becoming a director) by a person or coordinating group (as defined in IRS regulations) (other than Cargill and its subsidiaries) who beneficially owns 5% or more of our outstanding Common Stock.
	Although we are no longer restricted from engaging in Prohibited Acts, our indemnity to Cargill for any breach of the representations and warranties we made in support of the tax-free nature of the Merger, Split-off and Debt Exchange and any Prohibited Acts that occurred prior to May 26, 2013 remains in effect.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Significant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
	Statement Presentation and Basis of Consolidation
	The accompanying Consolidated Financial Statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”). Throughout the Notes to Consolidated Financial Statements, amounts in tables are in millions of dollars except for per share data and as otherwise designated. As previously reported, in 2013 we changed our fiscal year end to December 31 from May 31. We are presenting our results of operations for the twelve months ended December 31, 2014, the seven-month transition period of June 1, 2013 through December 31, 2013 (the “Stub Period”) and the fiscal years ended May 31, 2013 and 2012.
	The accompanying Consolidated Financial Statements include the accounts of Mosaic and its majority owned subsidiaries, as well as the accounts of certain variable interest entities, including PhosChem, for which we were the primary beneficiary. Effective December 31, 2013, we and PhosChem’s other member each assumed responsibility for PhosChem’s former activities as they related to our respective products.  We subsequently dissolved PhosChem and continue to sell our own product internationally.  PhosChem had net sales of $492.0 million for the seven months ended December 31, 2013 and $1.3 billion and $2.4 billion for the years ended May 31, 2013 and 2012, respectively, which are included in our consolidated net sales and had minimal impact on our gross margin. Certain investments in companies where we do not have control but have the ability to exercise significant influence are accounted for by the equity method.
	Accounting Estimates
	Preparation of the Consolidated Financial Statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting periods. The more significant estimates made by management relate to the recoverability of non-current assets including goodwill, the useful lives and net realizable values of long-lived assets, environmental and reclamation liabilities including asset retirement obligations (“AROs”), the costs of our employee benefit obligations for pension plans and postretirement benefits, income tax related accounts including the valuation allowance against deferred income tax assets, inventory valuation and accruals for pending legal and environmental matters. Actual results could differ from these estimates.
	Revenue Recognition
	Revenue on North American sales is recognized when the product is delivered to the customer and/or when the risks and rewards of ownership are otherwise transferred to the customer and when the price is fixed or determinable. Revenue on North American export sales is recognized upon the transfer of title to the customer and when the other revenue recognition criteria have been met, which generally occurs when product enters international waters. Revenue from sales originating outside of North America is recognized upon transfer of title to the customer based on contractual terms of each arrangement and when the other revenue recognition criteria have been met. Our products are generally sold based on the market prices prevailing at the time the sales contract is signed or through contracts which are priced at the time of shipment based on a formula. In certain circumstances, the final price of our products is determined after shipment based on the current market at the time the price is agreed to with the customer. In such circumstances, revenue is recognized when the final price is fixed and the other revenue recognition criteria have been met. Shipping and handling costs are included as a component of cost of goods sold.
	Non-Income Taxes
	We pay Canadian resource taxes consisting of the Potash Production Tax and resource surcharge. The Potash Production Tax is a Saskatchewan provincial tax on potash production and consists of a base payment and a profits tax. In addition to the Canadian resource taxes, royalties are payable to the mineral owners with respect to potash reserves or production of potash. These resource taxes and royalties are recorded in our cost of goods sold. Our Canadian resource tax and royalty expenses were $195.0 million for calendar 2014, $120.7 million for the seven months ended December 31, 2013, and $307.9 million and $327.1 million for fiscal 2013 and 2012, respectively.
	We have approximately $74 million of assets recorded as of December 31, 2014 related to PIS and Cofins, which is a Brazilian federal value-added tax, and income tax credits mostly earned in 2009 through 2014 that we believe will be realized through paying income taxes, paying other federal taxes, or receiving cash refunds. Should the Brazilian government determine that these are not valid credits upon audit, this could impact our results in such period. We have recorded the PIS and Cofins credits at amounts which are probable of collection. Information regarding PIS and Cofins taxes under audit, are included in Note 20 of our Notes to Consolidated Financial Statements
	Foreign Currency Translation
	The Company’s reporting currency is the U.S. dollar; however, for operations located in Canada and Brazil, the functional currency is the local currency. Assets and liabilities of these foreign operations are translated to U.S. dollars at exchange rates in effect at the balance sheet date, while income statement accounts and cash flows are translated to U.S. dollars at the average exchange rates for the period. For these operations, translation gains and losses are recorded as a component of accumulated other comprehensive income in equity until the foreign entity is sold or liquidated. Transaction gains and losses result from transactions that are denominated in a currency other than the functional currency of the operation, primarily accounts receivable in our Canadian entities denominated in U.S. dollars, and accounts payable in Brazil denominated in U.S. dollars. These foreign currency transaction gains and losses are presented separately in the Consolidated Statement of Earnings.
	Cash and Cash Equivalents
	Cash and cash equivalents include short-term, highly liquid investments with original maturities of 90 days or less, and other highly liquid investments that are payable on demand such as money market accounts, certain certificates of deposit and repurchase agreements. The carrying amount of such cash equivalents approximates their fair value due to the short-term and highly liquid nature of these instruments.
	Concentration of Credit Risk
	In the U.S., we sell our products to manufacturers, distributors and retailers primarily in the Midwest and Southeast. Internationally, our potash products are sold primarily through Canpotex, an export association. A concentration of credit risk arises from our sales and accounts receivable associated with the international sales of potash product through Canpotex. We consider our concentration risk related to the Canpotex receivable to be mitigated by their credit policy which requires the underlying receivables to be substantially insured or secured by letters of credit. As of December 31, 2014 and 2013, $118.0 million and $73.8 million, respectively, of accounts receivable were due from Canpotex. During calendar 2014, sales to Canpotex were $923.6 million, $439.7 million during the seven months ended December 31, 2013, and in fiscal 2013 and 2012, sales to Canpotex were $1.2 billion and $1.3 billion, respectively.
	Inventories
	Inventories of raw materials, work-in-process products, finished goods and operating materials and supplies are stated at the lower of cost or market. Costs for substantially all inventories are determined using the weighted average cost basis. To determine the cost of inventory, we allocate fixed expense to the costs of production based on the normal capacity, which refers to a range of production levels and is considered the production expected to be achieved over a number of periods or seasons under normal circumstances, taking into account the loss of capacity resulting from planned maintenance.
	Market value of our inventory is defined as forecasted selling prices less reasonably predictable selling costs (net realizable value). Significant management judgment is involved in estimating forecasted selling prices including various demand and supply variables. Examples of demand variables include grain and oilseed prices, stock-to-use ratios and changes in inventories in the crop nutrients distribution channels. Examples of supply variables include forecasted prices of raw materials, such as phosphate rock, sulfur, ammonia, and natural gas, estimated operating rates and industry crop nutrient inventory levels. Results could differ materially if actual selling prices differ materially from forecasted selling prices. Charges for lower of cost or market are recognized in our Consolidated Statements of Earnings in the period when there is evidence of a decline of market value below cost.
	Property, Plant and Equipment and Recoverability of Long-Lived Assets
	Property, plant and equipment are stated at cost. Costs of significant assets include capitalized interest incurred during the construction and development period. Repairs and maintenance, including planned major maintenance and plan turnaround costs, are expensed when incurred.
	Depletion expenses for mining operations, including mineral reserves, are generally determined using the units-of-production method based on estimates of recoverable reserves. Depreciation is computed principally using the straight-line method over the following useful lives: machinery and equipment three to 25 years, and buildings and leasehold improvements three to 40 years.
	We estimate initial useful lives based on experience and current technology. These estimates may be extended through sustaining capital programs. Factors affecting the fair value of our assets or periods of expected use may also affect the estimated useful lives of our assets and these factors can change. Therefore, we periodically review the estimated remaining lives of our facilities and other significant assets and adjust our depreciation rates prospectively where appropriate.
	Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. The carrying amount of a long-lived asset group is not recoverable if it exceeds the sum of the undiscounted cash flows expected to result from the use and eventual disposition of the asset group. If it is determined that an impairment loss has occurred, the loss is measured as the amount by which the carrying amount of the long-lived asset group exceeds its fair value.
	Leases
	Leases in which the risk of ownership is retained by the lessor are classified as operating leases. Leases which substantially transfer all of the benefits and risks inherent in ownership to the lessee are classified as capital leases. Assets acquired under capital leases are depreciated on the same basis as property, plant and equipment. Rental payments are expensed on a straight-line basis. Leasehold improvements are depreciated over the depreciable lives of the corresponding fixed assets or the related lease term, whichever is shorter.
	Contingencies
	Accruals for environmental remediation efforts are recorded when costs are probable and can be reasonably estimated. In determining these accruals, we use the most current information available, including similar past experiences, available technology, consultant evaluations, regulations in effect, the timing of remediation and cost-sharing arrangements.
	We are involved from time to time in claims and legal actions incidental to our operations, both as plaintiff and defendant. We have established what we currently believe to be adequate accruals for pending legal matters. These accruals are established as part of an ongoing worldwide assessment of claims and legal actions that takes into consideration such items as advice of legal counsel, individual developments in court proceedings, changes in the law, changes in business focus, changes in the litigation environment, changes in opponent strategy and tactics, new developments as a result of ongoing discovery, and past experience in defending and settling similar claims. The litigation accruals at any time reflect updated assessments of the then-existing claims and legal actions. The final outcome or potential settlement of litigation matters could differ materially from the accruals which we have established. For significant individual cases, we accrue legal costs expected to be incurred.
	Pension and Other Postretirement Benefits
	Mosaic offers a number of benefit plans that provide pension and other benefits to qualified employees. These plans include defined benefit pension plans, supplemental pension plans, defined contribution plans and other postretirement benefit plans.
	We accrue the funded status of our plans, which is representative of our obligations under employee benefit plans and the related costs, net of plan assets measured at fair value. The cost of pensions and other retirement benefits earned by employees is generally determined with the assistance of an actuary using the projected benefit method prorated on service and management’s best estimate of expected plan investment performance, salary escalation, retirement ages of employees and expected healthcare costs.
	Additional Accounting Policies
	To facilitate a better understanding of our consolidated financial statements we have disclosed the following significant accounting policies (with the exception of those identified above) throughout the following notes, with the related financial disclosures by major caption:
	Note	Topic	Page
	7	Earnings per Share	F-51
	9	Investments in Non-Consolidated Companies	F-53
	10	Goodwill	F-54
	12	Income Taxes	F-57
	13	Accounting for Asset Retirement Obligations	F-60
	14	Accounting for Derivative and Hedging Activities	F-61
	15	Fair Value Measurements	F-62
	18	Share Based Payments	F-67

Recently_Issued_Accounting_Gui

Recently Issued Accounting Guidance	12 Months Ended
	Dec. 31, 2014
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recently Issued Accounting Guidance	RECENTLY ISSUED ACCOUNTING GUIDANCE
	Recently Adopted Accounting Pronouncements
	In July 2013, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update ("ASU") No. 2013-11, “Income Taxes (Topic 740): Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists,” which requires that an unrecognized tax benefit should be presented in the financial statements as a reduction of a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward when settlement in this manner is available under the law. This guidance was effective for us beginning January 1, 2014 and was applied on a prospective basis to all unrecognized tax benefits that existed at the effective date. This guidance did not have a material impact on our results of operations or financial position.
	Pronouncements Issued But Not Yet Adopted
	In April 2014, the FASB issued ASU No. 2014-08, "Presentation of Financial Statements (Topic 205) and Property, Plant, and Equipment (Topic 360):  Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity", which changes the criteria for reporting a discontinued operation.  Under this standard, a disposal of part of an organization that has a major effect on its operations and financial results is a discontinued operation.  This guidance is effective prospectively for us beginning January 1, 2015 with earlier application permitted, but only for disposals (or classifications as held for sale) that have not been reported previously.  We do not expect that this guidance will have a material impact on our results of operations or financial position.
	In May 2014, the FASB issued ASU No. 2014-09, “Revenue from Contracts with Customers (Topic 606),” which requires revenue to be recognized based on the amount an entity is expected to be entitled to for promised goods or services provided to customers. The standard also requires expanded disclosures regarding contracts with customers. The guidance in this standard supersedes the revenue recognition requirements in Topic 605, "Revenue Recognition", and most industry-specific guidance. This guidance is effective for us beginning January 1, 2017. The standard permits the use of either the retrospective or cumulative effect transition method. We are currently evaluating the requirements of this standard, and have not yet determined the impact on our results of operations or financial position.

Other_Financial_Statement_Data

Other Financial Statement Data	12 Months Ended
	Dec. 31, 2014
Balance Sheet Related Disclosures [Abstract]
Other Financial Statement Data	OTHER FINANCIAL STATEMENT DATA
	The following provides additional information concerning selected balance sheet accounts:
		December 31,
	(in millions)	2014			2013
	Receivables
	Trade	$	624.9		$	460.1
	Non-trade	132.1			84.9
		757			545
	Less allowance for doubtful accounts	2.6			1.9
		$	754.4		$	543.1
	Inventories
	Raw materials	$	114.6		$	34
	Work in process	505.1			433.6
	Finished goods	1,025.50			891.6
	Operating materials and supplies	73.1			73.7
		$	1,718.30		$	1,432.90
	Other current assets
	Final price deferred(a)	$	49.9		$	154.3
	Income and other taxes receivable	201.9			272.6
	Prepaid expenses	63.8			115.8
	Assets held for sale(b)	6			111.9
	Other	46.6			52.2
		$	368.2		$	706.8
		December 31,
	(in millions)	2014			2013
	Accrued liabilities
	Non-income taxes	$	29.9		$	23.6
	Payroll and employee benefits	172.8			111.8
	Asset retirement obligations	87.9			86.3
	Customer prepayments	101.6			131.9
	Other	333.9			312.7
		$	726.1		$	666.3
	Other noncurrent liabilities
	Asset retirement obligations	$	771.6		$	637.6
	Accrued pension and postretirement benefits	77.6			69
	Unrecognized tax benefits	89.2			96.3
	Other	261.6			124.2
		$	1,200.00		$	927.1
	______________________________
	(a)	Final price deferred is product that has shipped to customers, but the price has not yet been agreed upon. This has not been included in inventory as it is not held for sale.
	(b)	See further description of assets held for sale in Footnote 22.
	Interest expense, net was comprised of the following in the calendar year 2014, seven months ended December 31, 2013, and fiscal 2013 and 2012:
		Year Ended			Seven Months Ended December 31,			Years Ended May 31,
		December 31,
	(in millions)	2014			2013			2013		2012
	Interest income	$	21.3		$	9.5		$	18.8	$	20.1
	Less interest expense	128.9			22.8			—		1.4
	Interest income (expense), net	$	(107.6	)	$	(13.3	)	$	18.8	$	18.7

Property_Plant_and_Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Property Plant And Equipment	PROPERTY, PLANT AND EQUIPMENT
	Property, plant and equipment consist of the following:
		December 31,
	(in millions)	2014		2013
	Land	$	233.7	$	188.6
	Mineral properties and rights	3,515.50		2,932.60
	Buildings and leasehold improvements	2,242.00		1,969.50
	Machinery and equipment	6,660.60		5,994.10
	Construction in-progress	1,295.50		1,516.80
		13,947.30		12,601.60
	Less: accumulated depreciation and depletion	4,633.40		4,025.00
		$	9,313.90	$	8,576.60
	Depreciation and depletion expense was $750.9 million for calendar 2014, $386.2 million for the seven months ended December 31, 2013 and $604.8 million and $508.1 million for fiscal 2013 and 2012, respectively. Capitalized interest on major construction projects was $34.0 million for calendar 2014, $25.0 million for the seven months ended December 31, 2013 and $52.0 million and $55.7 million in fiscal 2013 and 2012, respectively.

Earnings_Per_Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Earnings per share	EARNINGS PER SHARE
	We use the two-class method to compute basic and diluted EPS. Earnings for the period are allocated pro-rata between the common shareholders and the participating securities. Our only participating securities are related to the Share Repurchase Agreement. The numerator for basic and diluted EPS is net earnings for common stockholders. The denominator for basic EPS is the weighted-average number of shares outstanding during the period. The denominator for diluted EPS also includes the weighted average number of additional common shares that would have been outstanding if the dilutive potential common shares had been issued, unless the shares are anti-dilutive, and excludes shares subject to forward contracts.
	The following is a reconciliation of the numerator and denominator for the basic and diluted EPS computations:
		Year Ended			Seven Months Ended			Years Ended May 31,
		December 31,			December 31,
	(in millions)	2014			2013			2013		2012
	Net earnings attributed to Mosaic	$	1,028.60		$	340		$	1,888.70	$	1,930.20
	Undistributed earnings attributable to participating securities	(22.3		)	(4.0		)	—		—
	Numerator for basic and diluted earnings available to common stockholders	$	1,006.30		$	336		$	1,888.70	$	1,930.20
	Basic weighted average number of shares outstanding	382.4			425.9			425.7		435.2
	Shares subject to forward contract	(8.3		)	(5.1		)	—		—
	Basic weighted average number of shares outstanding attributable to common stockholders	374.1			420.8			425.7		435.2
	Dilutive impact of share-based awards	1.5			1.2			1.2		1.3
	Diluted weighted average number of shares outstanding	375.6			422			426.9		436.5
	Basic net earnings per share	$	2.69		$	0.8		$	4.44	$	4.44
	Diluted net earnings per share	$	2.68		$	0.8		$	4.42	$	4.42
	A total of 1.3 million shares for calendar 2014, 1.1 million shares for the seven months ended December 31, 2013, 0.6 million shares for fiscal 2013 and 0.5 million shares for fiscal 2012 of common stock subject to issuance upon exercise of stock options have been excluded from the calculation of diluted EPS because the effect would be anti-dilutive.

Cash_Flow_Information

Cash Flow Information	12 Months Ended
	Dec. 31, 2014
Supplemental Cash Flow Elements [Abstract]
Cash Flow Information	CASH FLOW INFORMATION
	Supplemental disclosures of cash paid for interest and income taxes and non-cash investing and financing information is as follows:
		Year Ended		Seven Months Ended		Years Ended May 31,
		December 31,		December 31,
	(in millions)	2014		2013		2013		2012
	Cash paid during the period for:
	Interest	$	155.9	$	28.7	$	52	$	76.7
	Less amount capitalized	34		25		52		55.7
	Cash interest, net	$	121.9	$	3.7	$	—	$	21
	Income taxes	$	113.2	$	155.7	$	299.9	$	516.4
	Acquiring or constructing property, plant and equipment by incurring a liability does not result in a cash outflow for us until the liability is paid. In the period the liability is incurred, the change in operating accounts payable on the Consolidated Statements of Cash Flows is adjusted by such amount. In the period the liability is paid, the amount is reflected as a cash outflow from investing activities. The applicable net change in operating accounts payable that was classified to investing activities on the Consolidated Statements of Cash Flows was $29.3 million for calendar 2014, $87.7 million for the seven months ended December 31, 2013 and $54.6 million and $56.7 million, for fiscal 2013 and 2012, respectively.
	In September 2014, we accrued $120 million representing the remaining liability for our portion of mineral rights value transferred to the Wa’ad Al Shamal Joint Venture from Ma’aden.  The offset to this non-current liability was recorded as an investment in nonconsolidated companies.  This amount is expected to be paid in 2016.

Investments_in_Nonconsolidated

Investments in Non-consolidated Companies	12 Months Ended
	Dec. 31, 2014
Equity Method Investments and Joint Ventures [Abstract]
Investments in non-consolidated companies	INVESTMENTS IN NON-CONSOLIDATED COMPANIES
	We have investments in various international and domestic entities and ventures. The equity method of accounting is applied to such investments when the ownership structure prevents us from exercising a controlling influence over operating and financial policies of the businesses but still allow us to have significant influence. Under this method, our equity in the net earnings or losses of the investments is reflected as equity in net earnings of non-consolidated companies on our Consolidated Statements of Earnings. The effects of material intercompany transactions with these equity method investments are eliminated, including the gross profit on sales to and purchases from our equity-method investments which is deferred until the time of sale to the final third party customer. The cash flow presentation of dividends received from equity method investees is determined by evaluation of the facts, circumstances and nature of the distribution.
	A summary of our equity-method investments, which were in operation as of December 31, 2014, is as follows:
	Entity		Economic Interest
	Gulf Sulphur Services LTD., LLLP		50	%
	River Bend Ag, LLC		50	%
	IFC S.A.		45	%
	Yunnan Three Circles Sinochem Cargill Fertilizers Co. Ltd.		35	%
	Miski Mayo Mine		35	%
	Wa’ad Al Shamal Joint Venture		25	%
	Canpotex		38.8	%
	The summarized financial information shown below includes all non-consolidated companies carried on the equity method.
		Year Ended			Seven Months Ended December 31,		Years Ended May 31,
		December 31,
	(in millions)	2014			2013		2013		2012
	Net sales	$	3,814.10		$	1,846.50	$	4,475.20	$	4,938.40
	Net earnings	20			12.1		67.5		97.9
	Mosaic’s share of equity in net earnings (loss)	(2.2		)	10.9		18.3		13.3
	Total assets	4,344.90			1,658.50		1,841.40		1,776.00
	Total liabilities	3,107.00			985.3		1,149.80		1,005.00
	Mosaic’s share of equity in net assets	394			250.9		256.4		282.8
	The difference between our share of equity in net assets as shown in the above table and the investment in non-consolidated companies as shown on the Consolidated Balance Sheets is due to an excess amount paid over the book value of the Miski Mayo Mine. The excess relates to phosphate rock reserves adjusted to fair value in relation to the Miski Mayo Mine. The excess amount is amortized over the estimated life of the phosphate rock reserves and is net of related deferred income taxes. The investment in non-consolidated companies on the Consolidated Balance Sheets also includes $120 million accrued for a future capital commitment to the Wa'ad Al Shamal Joint Venture for a portion of mineral rights that were transferred from Ma'aden.
	The Wa’ad Al Shamal Joint Venture is developing a mine and two chemical complexes that are presently expected to produce phosphate fertilizers, animal feed, food grade purified phosphoric acid and other downstream phosphates products in the Kingdom of Saudi Arabia. We currently estimate that the cost to develop and construct the integrated phosphate production facilities (the "Project") will approximate $7.5 billion, which we expect to be funded primarily through investments by us, Ma'aden and SABIC, and through borrowing arrangements and other external project financing facilities ("Funding Facilities"). The facilities are expected to have a production capacity of approximately 3.5 million tonnes of finished product per year. Operations are expected to commence in late 2016. We will market approximately 25% of the production of the joint venture.
	On June 30, 2014, the Wa’ad Al Shamal Joint Venture entered into Funding Facilities with a consortium of 20 financial institutions for a total amount of approximately $5.0 billion.
	Also on June 30, 2014, in support of the Funding Facilities, we, together with Ma’aden and SABIC, agreed to provide our respective proportionate shares of the funding necessary for the Wa’ad Al Shamal Joint Venture by:
	(a)	Contributing equity or making shareholder subordinated loans of up to $2.4 billion to fund project costs to complete and commission the Project (the “Equity Commitments”).
	(b)	Through the earlier of Project completion or June 30, 2020, contributing equity, making shareholder subordinated loans or providing bank subordinated loans, to fund cost overruns on the Project (the “Additional Cost Overrun Commitment”).
	(c)	Through the earlier of Project completion or June 30, 2020, contributing equity, making shareholder loans or providing bank subordinated loans, to fund scheduled debt service (excluding accelerated amounts) payable under the Funding Facilities and certain other amounts (such commitment, the “DSU Commitment” and such scheduled debt service and other amounts, “Scheduled Debt Service”). Our proportionate share of amounts covered by the DSU Commitment is not anticipated to exceed approximately $200 million. The fair value of the DSU Commitment at December 31, 2014 is not material.
	(d)	To the extent that, by December 31, 2016, the Wa’ad Al Shamal Joint Venture has not received payment of certain governmental funding that has been allocated for the development of infrastructure assets to be utilized for the Project in the amount of at least $260 million, providing subordinated bridge loans to the Wa’ad Al Shamal Joint Venture (the “IFA Bridge Loan”).
	(e)	From the earlier of the project completion date or June 30, 2020, to the extent there is a shortfall in the amounts available to pay Scheduled Debt Service, depositing for the payment of Scheduled Debt Service an amount up to the respective amount of certain shareholder tax amounts, and severance fees under the Wa’ad Al Shamal Joint Venture's mining license, paid within the prior 36 months by Wa’ad Al Shamal Joint Venture on behalf of us, Ma’aden and SABIC, if any.
	The Wa’ad Al Shamal Joint Venture has not yet entered into definitive agreements for certain of the planned Funding Facilities (the “Future Funding Facilities”) for the Project, and the definitive terms with respect to these Future Funding Facilities have not been established. To the extent that the Wa’ad Al Shamal Joint Venture does not obtain definitive commitments for certain of these Future Finance Facilities in the amount of approximately $560 million aggregate principal amount by June 30, 2016, we, together with Ma’aden and SABIC, have agreed to either arrange for other Future Funding Facilities or provide funding in the form of financial indebtedness to the Wa’ad Al Shamal Joint Venture in the amount of our respective proportionate shares of the shortfall.
	We anticipate that, in connection with the Future Finance Facilities, we and the Wa’ad Al Shamal Joint Venture will undertake obligations in addition to the current Equity Commitments, the Additional Cost Overrun Commitment, the DSU Commitment and the IFA Bridge Loan.
	We currently estimate that our cash investment in the Project, including the amount we have invested to date, will approximate $850 million. Our estimate of the $850 million consists of our share of the Equity Commitments and our payments for mineral rights. As of December 31, 2014, our investment was $448.5 million, which includes $120 million accrued for a future capital commitment. All other commitments, other than the Equity Commitment, are not included in our $850 million estimate as it is remote that we would have to provide under these commitments.

Goodwill

Goodwill	12 Months Ended
	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	GOODWILL
	Goodwill is carried at cost, not amortized, and represents the excess of the purchase price and related costs over the fair value assigned to the net identifiable assets of a business acquired. We test goodwill for impairment on a quantitative basis at the reporting unit level on an annual basis or upon the occurrence of events that may indicate possible impairment. The test resulted in no impairment in the periods presented.
	The changes in the carrying amount of goodwill, by reporting unit, as of December 31, 2014 and 2013, are as follows:
	(in millions)	Phosphates		Potash		Total
	Balance as of May 31, 2013	546.6		1,298.00		1,844.60
	Foreign currency translation	—		(39.4	)	(39.4	)
	Reallocation of goodwill to assets held for sale	(10.8	)	—		(10.8	)
	Balance at December 31, 2013	535.8		1,258.60		1,794.40
	Foreign currency translation	1.6		(95.7	)	(94.1	)
	Goodwill acquired in ADM acquisition	105.9		—		105.9
	Reallocation of goodwill to assets held for sale	5.1		(4.8	)	0.3
	Balance as of December 31, 2014	648.4		1,158.10		1,806.50
	As of December 31, 2014, $365.3 million of goodwill was tax deductible.

Financing_Arrangements

Financing Arrangements	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Financing Arrangements	FINANCING ARRANGEMENTS
	Mosaic Credit Facility
	We have an unsecured five-year revolving credit facility of up to $1.5 billion (the “Mosaic Credit Facility”) which is intended to serve as our primary senior unsecured bank credit facility to meet the combined liquidity needs of all of our business segments. The maturity date of the Mosaic Credit Facility is December 5, 2018.
	The Mosaic Credit Facility has cross-default provisions that, in general, provide that a failure to pay principal or interest under any one item of other indebtedness in excess of $50 million or $75 million for multiple items of other indebtedness, or breach or default under such indebtedness that permits the holders thereof to accelerate the maturity thereof, will result in a cross-default.
	The Mosaic Credit Facility requires Mosaic to maintain certain financial ratios, including a maximum ratio of Total Debt to EBITDA (as defined) of 3.5 to 1.0 as well as a minimum Interest Coverage Ratio (as defined) of not less than 3.0 to 1.0.
	The Mosaic Credit Facility also contains other events of default and covenants that limit various matters. These provisions include limitations on indebtedness, liens, investments and acquisitions (other than capital expenditures), certain mergers, certain sales of assets and other matters customary for credit facilities of this nature.
	Short-Term Debt
	Short-term debt consists of the revolving credit facility under the Mosaic Credit Facility, under which there were no borrowings as of December 31, 2014 and 2013, and various other short-term borrowings related to our international distribution activities. These short-term borrowings outstanding were $13.5 million as of December 31, 2014, are denominated in various currencies and bear interest at rates between 6.0% and 10.8% and mature at various dates in 2015.
	We had outstanding letters of credit that utilized a portion of the amount available for revolving loans under the Mosaic Credit Facility of $23.1 million and $19.0 million as of December 31, 2014 and 2013, respectively. The net available borrowings for revolving loans under the Mosaic Credit Facility as of December 31, 2014 and 2013 were approximately $1,476.9 million and $1,481.0 million, respectively. Unused commitment fees under the Mosaic Credit Facility accrued at an average annual rate of 0.125% for calendar 2014, and 0.19% for the 7 months ended December 31, 2013, 0.20% for fiscal 2013 and 0.21% for fiscal 2012, generating expenses of $1.9 million, $0.9 million, $1.5 million and $1.6 million, respectively.
	We had additional outstanding letters of credit of $7.1 million as of December 31, 2014.
	Long-Term Debt, including Current Maturities
	On March 20, 2014, Mosaic entered into the Term Loan Facility with certain financial institutions. The Term Loan Facility consists of $370 million Term A-1 Loans (the “Term A-1 Loans”) and $430 million Term A-2 Loans (“Term A-2 Loans,” and collectively with the Term A-1 Loans, “Loans”).
	On September 18, 2014, Mosaic borrowed the entire amount available under the Term Loan Facility.
	Final maturity of the Term A-1 Loans is September 18, 2017 and final maturity of the Term A-2 Loans is September 18, 2019. In addition, Mosaic is required to repay 5.00% of the Term A-1 loan balance on each of September 18, 2015 and 2016 and 5.00% of the Term A-2 loan balance on each of September 18, 2015 and 2016, 7.50% on September 18, 2017, and 10.00% on September 18, 2018. Mosaic may prepay outstanding Term A-1 Loans and Term A-2 Loans at any time and from time to time, without premium or penalty. The interest rate currently applicable to outstanding Loans is LIBOR plus 1.125%.
	Net proceeds from borrowings under the Term Loan Facility replaced a portion of the cash that Mosaic used to fund the CF Phosphate Assets Acquisition and certain related liabilities on March 17, 2014. Under the Term Loan Facility, proceeds of borrowings may also be used for working capital, capital expenditures, dividends, share repurchases, other acquisitions and other lawful corporate purposes.
	The Term Loan Facility has default provisions and covenants similar to those under the Mosaic Credit Facility.
	On November 7, 2013, we completed a $2 billion public offering consisting of $900 million aggregate principal amount of 4.25% Senior Notes due 2023, $500 million aggregate principal amount of 5.45% Senior Notes due 2033, and $600 million aggregate principal amount of 5.625% Senior Notes due 2043 (collectively, the “Senior Notes of 2013”).
	We received net proceeds from this offering of approximately $1.98 billion, which we used for general corporate purposes, including, without limitation, working capital, capital expenditures, strategic opportunities and distributions to our stockholders, either in the form of share repurchases or dividends.
	The Senior Notes of 2013 are Mosaic’s senior unsecured obligations and rank equally in right of payment with Mosaic’s existing and future senior unsecured indebtedness. The indenture governing the Senior Notes of 2013 contains restrictive covenants limiting debt secured by liens, sale and leaseback transactions and mergers, consolidations and sales of substantially all assets as well as other events of default.
	We have additional senior notes outstanding, consisting of $450 million aggregate principal amount of 3.750% senior notes due 2021 and $300 million aggregate principal amount of 4.875% Senior Notes due 2041 (collectively, the “Senior Notes of 2011”).
	Two debentures, issued by Mosaic Global Holdings, Inc., one of our consolidated subsidiaries, the first due in 2018 (the “2018 Debentures”) and the second due in 2028 (the “2028 Debentures”) remain outstanding with balances of $89.0 million and $147.1 million, respectively, as of December 31, 2014. The indentures governing the 2018 Debentures and the 2028 Debentures also contain restrictive covenants limiting debt secured by liens, sale and leaseback transactions and mergers, consolidations and sales of substantially all assets as well as events of default. The obligations under the 2018 Debentures and the 2028 Debentures are guaranteed by several of the Company’s subsidiaries.
	Long-term debt primarily consists of term loans, industrial revenue bonds, secured notes, unsecured notes, and unsecured debentures. Long-term debt as of December 31, 2014 and 2013, respectively, consisted of the following:
	(in millions)		December 31,	December 31,	Maturity Date	December 31,		Combination Fair		Discount on Notes Issuance			December 31,		December 31,		Combination Fair		Discount on Notes Issuance			December 31,
			2014	2014		2014		Market					2014		2013		Market					2013
			Stated	Effective		Stated		Value Adjustment					Carrying		Stated		Value Adjustment					Carrying
			Interest	Interest		Value							Value		Value							Value
			Rate	Rate
	Industrial revenue and recovery zone bonds		1.15%	1.15%	2040	$	15.9	$	—	$	—		$	15.9	$	16.8	$	—	$	—		$	16.8
	Unsecured notes		3.75% -	4.73%	2021-	2,750.00		—		(10.1		)	2,739.90		2,750.00		—		(11.2		)	2,738.80
			5.63%		2043
	Unsecured debentures		7.30% -	7.08%	2018-	236.1		2.8		—			238.9		236.1		3.1		—			239.2
			7.38%		2028
	Term Loans		Libor plus 1.125%	1.28%	2017-	800		—		—			800		—		—		—			—
					2019
	Other		2.50% -	6.59%	2014-	24.3		—		—			24.3		14.5		—		—			14.5
			9.00%		2023
	Total long-term debt					3,826.30		2.8		(10.1		)	3,819.00		3,017.40		3.1		(11.2		)	3,009.30
	Less current portion					41.6		0.4		(1.0		)	41		1.1		0.4		(1.1		)	0.4
	Total long-term debt, less current maturities					$	3,784.70	$	2.4	$	(9.1	)	$	3,778.00	$	3,016.30	$	2.7	$	(10.1	)	$	3,008.90
	Scheduled maturities of long-term debt are as follows for the periods ending December 31:
	(in millions)
	2015	$	41
	2016	43.7
	2017	365.9
	2018	132.4
	2019	315.7
	Thereafter	2,920.30
	Total	$	3,819.00

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES
	In preparing our Consolidated Financial Statements, we utilize the asset and liability approach in accounting for income taxes. We recognize income taxes in each of the jurisdictions in which we have a presence. For each jurisdiction, we estimate the actual amount of income taxes currently payable or receivable, as well as deferred income tax assets and liabilities attributable to temporary differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred income tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which these temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date.
	The provision for income taxes for calendar 2014, the seven months ended December 31, 2013, and the fiscal years ended May 31, 2013 and 2012 consisted of the following:
		Year Ended			Seven Months Ended December 31,			Years Ended May 31,
		December 31,
	(in millions)	2014			2013			2013			2012
	Current:
	Federal	$	46		$	(25.0	)	$	138.8		$	314.5
	State	11.8			(15.1		)	42.5			61
	Non-U.S.	265.4			141.9			81.5			77
	Total current	323.2			101.8			262.8			452.5
	Deferred:
	Federal	(103.6		)	32.8			(32.9		)	7.4
	State	(16.4		)	(0.3		)	(14.1		)	9
	Non-U.S.	(18.5		)	18.3			125.2			242.5
	Total deferred	(138.5		)	50.8			78.2			258.9
	Provision for income taxes	$	184.7		$	152.6		$	341		$	711.4
	The components of earnings from consolidated companies before income taxes, and the effects of significant adjustments to tax computed at the federal statutory rate, were as follows:
		Year Ended			Seven Months Ended December 31,			Years Ended May 31,
		December 31,
	(in millions)	2014			2013			2013			2012
	United States earnings	$	312.9		$	208.2		$	1,158.10		$	1,412.70
	Non-U.S. earnings	904.4			276			1,056.40			1,216.20
	Earnings from consolidated companies before income taxes	$	1,217.30		$	484.2		$	2,214.50		$	2,628.90
	Computed tax at the U.S. federal statutory rate of 35%	35		%	35		%	35		%	35		%
	State and local income taxes, net of federal income tax benefit	0.1		%	1.2		%	1.6		%	1.6		%
	Percentage depletion in excess of basis	(9.7		)%	(15.7		)%	(7.1		)%	(6.6		)%
	Impact of non-U.S. earnings	(3.8		)%	3.8		%	(10.2		)%	(2.9		)%
	Non-taxable change in value of share repurchase agreement	1.7		%	(5.3		)%	—		%	—		%
	Change in valuation allowance	(7.6		)%	10		%	(3.6		)%	0.4		%
	Other items (none in excess of 5% of computed tax)	(0.5		)%	2.5		%	(0.3		)%	(0.4		)%
	Effective tax rate	15.2		%	31.5		%	15.4		%	27.1		%
	In the year ended December 31, 2014, the impact of non-U.S. earnings included a cost of $81.0 million related to certain non-U.S. subsidiaries where our earnings were not permanently re-invested, a deferred tax benefit of $47.0 million related to a change in the tax status of a Brazilian subsidiary and a benefit of $8.1 million related to the settlement of certain non-U.S. tax matters. The non-U.S. earnings is also impacted by the mix of earnings across the jurisdictions in which we operate.  In addition, the effective rate reflects decreases of $32.8 million related to the release of valuation allowances related to net operating losses and other deferred tax assets at a Brazilian subsidiary, and $53.6 million related to losses on the sale of our distribution business in Argentina, which are both reflected in the change in valuation allowance above.
	The seven months ended December 31, 2013 reflect increased expenses of $4.0 million related to the resolution of certain multi-jurisdictional tax matters and $100.8 million due to no longer being permanently re-invested in certain non-U.S. subsidiaries, which are included in the impact of non-U.S. earnings above.
	The fiscal 2013 effective tax rate reflects a decrease of $179.3 million due to the resolution of certain tax matters, which is included in the impact of non-U.S. earnings above.
	Significant components of our deferred tax liabilities and assets as of December 31 were as follows:
		December 31,
	(in millions)	2014			2013
	Deferred tax liabilities:
	Depreciation and amortization	$	897.9		$	1,029.80
	Depletion	397.9			388.6
	Partnership tax basis differences	120.1			106.2
	Undistributed earnings of non-U.S. subsidiaries	219.5			319.6
	Other liabilities	41.5			150.9
	Total deferred tax liabilities	$	1,676.90		$	1,995.10
	Deferred tax assets:
	Alternative minimum tax credit carryforwards	$	144.5		$	113.8
	Capital loss carryforwards	—			54.6
	Foreign tax credit carryforwards	450.5			580.9
	Net operating loss carryforwards	103.1			145.3
	Pension plans and other benefits	29.1			17.1
	Asset retirement obligations	263.7			260
	Other assets	269.7			182.7
	Subtotal	1,260.60			1,354.40
	Valuation allowance	28.3			129.2
	Net deferred tax assets	1,232.30			1,225.20
	Net deferred tax liabilities	$	(444.6	)	$	(769.9	)
	We have certain entities that are taxed in both their local currency jurisdiction and the U.S. As a result, we have deferred tax balances for both jurisdictions. As of December 31, 2014 and 2013, these non-U.S. deferred taxes are offset by approximately $457.0 million and $384.9 million, respectively, of anticipated foreign tax credits included within our depreciation and depletion components of deferred tax liabilities above.
	As of December 31, 2014, we had estimated carryforwards for tax purposes as follows: alternative minimum tax credits of $144.5 million, net operating losses of $343.1 million and foreign tax credits of $450.5 million. These carryforward benefits may be subject to limitations imposed by the Internal Revenue Code, and in certain cases, provisions of foreign law. The alternative minimum tax credit carryforwards can be carried forward indefinitely. The majority of our net operating loss carryforwards relate to Brazil and can be carried forward indefinitely but are limited to 30 percent of taxable income each year. Of the $450.5 million of foreign tax credits, approximately $350 million have an expiration date of calendar 2018 or earlier. The majority of the remaining balance expires in calendar 2023. The realization of our foreign tax credit carryforwards is dependent on market conditions, repatriation of the undistributed earnings of certain non-U.S. subsidiaries, and other business outcomes. We will need certain types of taxable income totaling approximately $1.3 billion in the U.S. between calendar 2014 and calendar 2023 to fully utilize our foreign tax credit carryforwards, the majority of which must be earned before calendar 2018.
	We have no intention of remitting certain undistributed earnings of non-U.S. subsidiaries aggregating $2.2 billion as of December 31, 2014, and accordingly, no deferred tax liability has been established relative to these earnings. Generally, such amounts become subject to U.S. taxation upon the remittance of dividends and under certain other circumstances. The calculation of the unrecognized deferred tax liability related to these earnings is complex and is not practicable.
	Valuation Allowance
	In assessing the need for a valuation allowance, we consider whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. We evaluate our ability to realize the tax benefits associated with deferred tax assets by analyzing the relative impact of all the available positive and negative evidence regarding our forecasted taxable income using both historical and projected future operating results, the reversal of existing taxable temporary differences, taxable income in prior carry-back years (if permitted) and the availability of tax planning strategies. The ultimate realization of deferred tax assets is dependent upon the generation of certain types of future taxable income during the periods in which those temporary differences become deductible. In making this assessment, we consider the scheduled reversal of deferred tax liabilities, our ability to carry back the deferred tax asset, projected future taxable income, and tax planning strategies. A valuation allowance will be recorded in each jurisdiction in which a deferred income tax asset is recorded when it is more likely than not that the deferred income tax asset will not be realized. Changes in deferred tax asset valuation allowances typically impact income tax expense.
	Prior to the year ended December 31, 2014, we had provided a valuation allowance for deferred tax assets primarily related to net operating losses at certain non-U.S. subsidiaries. As of December 31, 2014, we determined that sufficient positive evidence existed to conclude it was more likely than not that we would realize the benefits of the net operating loss and other deferred tax assets at a Brazilian subsidiary for which a valuation allowance had been recorded. We also concluded that it was more likely than not that we would realize the benefits related to losses on the sale of a distribution business in a non-U.S. subsidiary. Accordingly, during the year ended December 31, 2014, the valuation allowance decreased $100.9 million primarily related to these two items.
	For the seven months ended December 31, 2013, the valuation allowance increased $35.4 million primarily due to our determination that it was not more likely than not that we would be able to utilize the anticipated capital loss resulting from the write down of our distribution business in Argentina and Chile.
In fiscal 2013, the valuation allowance decreased $86.6 million primarily due to our determination that the valuation allowance against certain non-U.S. deferred tax assets recorded in prior fiscal years could be reduced. In fiscal 2012, the valuation allowance decreased by $29.0 million.
Uncertain Tax Positions
Accounting for uncertain income tax positions is determined by prescribing a minimum probability threshold that a tax position must meet before a financial statement benefit is recognized. This minimum threshold is that a tax position is more likely than not to be sustained upon examination by the applicable taxing authority, including resolution of any related appeals or litigation processes, based on the technical merits of the position. The tax benefit to be recognized is measured as the largest amount of benefit that is greater than a fifty percent likelihood of being realized upon ultimate settlement.
As of December 31, 2014, we had $100.6 million of gross uncertain tax positions. If recognized, the benefit to our effective tax rate in future periods would be approximately $100.0 million of that amount. During calendar 2014, we recorded gross increases in our uncertain tax positions of $21.3 million related to certain non-U.S. tax matters, which partially offset the decrease of $32.6 million on the same matter. The impact to the effective rate was a decrease to the expense of $8.1 million, net of offsetting items not included in gross uncertain tax positions.
We also recorded a gross increase of $11.7 million relating to other matters impacting prior fiscal years, which did not impact our effective rate.
Based upon the information available as of December 31, 2014, we anticipate that the amount of uncertain tax positions will change in the next twelve months; however, the change cannot reasonably be estimated.
	Year Ended December 31,			Seven Months Ended December 31,			Year ended May 31,
(in millions)	2014			2013			2013
Gross unrecognized tax benefits, beginning of period	$	99.2		$	316.8		$	476.9
Gross increases:
Prior period tax positions	33			128.5			7.7
Current period tax positions	2.8			0.4			36.6
Gross decreases:
Prior period tax positions	—			(24.0		)	(204.3		)
Settlements	(32.6		)	(323.7		)	—
Currency translation	(1.8		)	1.2			(0.1		)
Gross unrecognized tax benefits, end of period	$	100.6		$	99.2		$	316.8
We recognize interest and penalties related to unrecognized tax benefits as a component of our income tax expense. Interest and penalties accrued in our Consolidated Balance Sheets as of December 31, 2014 and 2013 are $20.0 million and $28.8 million, respectively, and are included in other noncurrent liabilities in the Consolidated Balance Sheets.
We operate in multiple tax jurisdictions, both within the United States and outside the United States, and face audits from various tax authorities regarding transfer pricing, deductibility of certain expenses, and intercompany transactions, as well as other matters. With few exceptions, we are no longer subject to examination for tax years prior to 2008.
We are currently under audit by the U.S. Internal Revenue Service for fiscal 2011 and 2012 and by the Canada Revenue Agency for fiscal 2008 to 2013. Based on the information available, we do not anticipate significant changes to our unrecognized tax benefits as a result of these examinations.

Accounting_for_Asset_Retiremen

Accounting for Asset Retirement Obligations	12 Months Ended
	Dec. 31, 2014
Asset Retirement Obligation Disclosure [Abstract]
Accounting for Asset Retirement Obligations	ACCOUNTING FOR ASSET RETIREMENT OBLIGATIONS
	We recognize AROs in the period in which we have an existing legal obligation associated with the retirement of a tangible long-lived asset, and the amount of the liability can be reasonably estimated. The ARO is recognized at fair value when the liability is incurred with a corresponding increase in the carrying amount of the related long lived asset. We depreciate the tangible asset over its estimated useful life. The liability is adjusted in subsequent periods through accretion expense which represents the increase in the present value of the liability due to the passage of time. Such depreciation and accretion expenses are included in cost of goods sold for operating facilities and other operating expense for indefinitely closed facilities.
	Our legal obligations related to asset retirement require us to: (i) reclaim lands disturbed by mining as a condition to receive permits to mine phosphate ore reserves; (ii) treat low pH process water in phosphogypsum management systems (the “Gypstacks”) to neutralize acidity; (iii) close and monitor Gypstacks at our Florida and Louisiana facilities at the end of their useful lives; (iv) remediate certain other conditional obligations; (v) remove all surface structures and equipment, plug and abandon mine shafts, contour and revegetate, as necessary, and monitor for five years after closing our Carlsbad, New Mexico facility and (vi) decommission facilities, manage tailings and execute site reclamation at our Saskatchewan potash mines at the end of their useful lives. The estimated liability for these legal obligations is based on the estimated cost to satisfy the above obligations which is discounted using a credit-adjusted risk-free rate.
	A reconciliation of our AROs is as follows:
		Year Ended December 31,			Seven Months Ended December 31,
	(in millions)	2014			2013
	AROs, beginning of period	$	723.9		$	658.5
	Liabilities acquired in CF Phosphate Assets Acquisition	145.6			—
	Liabilities incurred	21.7			13.6
	Liabilities settled	(91.1		)	(37.0		)
	Accretion expense	42.1			21.6
	Revisions in estimated cash flows	17.3			67.2
	AROs, end of period	859.5			723.9
	Less current portion	87.9			86.3
		$	771.6		$	637.6

Accounting_for_Derivative_Inst

Accounting for Derivative Instruments and Hedging Activities	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Accounting for Derivative Instruments and Hedging Activities	ACCOUNTING FOR DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES
	We periodically enter into derivatives to mitigate our exposure to foreign currency risks and the effects of changing commodity and freight prices. We record all derivatives on the Consolidated Balance Sheets at fair value. The fair value of these instruments is determined by using quoted market prices, third party comparables, or internal estimates. We net our derivative asset and liability positions when we have a master netting arrangement in place. Changes in the fair value of the foreign currency, commodity, and freight derivatives are immediately recognized in earnings because we do not apply hedge accounting treatment to these instruments. As of December 31, 2014 and 2013, the gross asset position of our derivative instruments was $9.0 million and $7.9 million, respectively, and the gross liability position of our liability instruments was $54.8 million and $20.4 million, respectively.
	We do not apply hedge accounting treatments to our foreign currency exchange contracts, commodities contracts, or freight contracts. Unrealized gains and (losses) on foreign currency exchange contracts used to hedge cash flows related to the production of our product are included in cost of goods sold in the Consolidated Statements of Earnings. Unrealized gains and (losses) on commodities contracts and certain forward freight agreements are also recorded in cost of goods sold in the Consolidated Statements of Earnings. Unrealized gains or (losses) on foreign currency exchange contracts used to hedge cash flows that are not related to the production of our products are included in the foreign currency transaction gain (loss) line in the Consolidated Statements of Earnings.
	The following is the total absolute notional volume associated with our outstanding derivative instruments:
	(in millions of Units)
	Instrument	Derivative Category	Unit of Measure	December 31,	December 31,
				2014	2013
	Foreign currency derivatives	Foreign Currency	US Dollars	1,132.30	940.2
	Natural gas derivatives	Commodity	MMbtu	24.4	8.2
	Credit-Risk-Related Contingent Features
	Certain of our derivative instruments contain provisions that require us to post collateral. These provisions also state that if our debt were to be rated below investment grade, certain counterparties to the derivative instruments could request full collateralization on derivative instruments in net liability positions. The aggregate fair value of all derivative instruments with credit-risk-related contingent features that were in a liability position as of December 31, 2014 and 2013 was $41.7 million and $12.3 million, respectively. We have not posted cash collateral in the normal course of business associated with these contracts. If the credit-risk-related contingent features underlying these agreements were triggered on December 31, 2014, we would be required to post an additional $40.7 million of collateral assets, which are either cash or U.S. Treasury instruments, to the counterparties.
	Counterparty Credit Risk
	We enter into foreign exchange and certain commodity derivatives, primarily with a diversified group of highly rated counterparties. We continually monitor our positions and the credit ratings of the counterparties involved and limit the amount of credit exposure to any one party. While we may be exposed to potential losses due to the credit risk of non-performance by these counterparties, losses are not anticipated. We closely monitor the credit risk associated with our counterparties and customers and to date have not experienced material losses.

Fair_Value_Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS
	Following is a summary of the valuation techniques for assets and liabilities recorded in our Consolidated Balance Sheets at fair value on a recurring basis:
	Foreign Currency Derivatives—The foreign currency derivative instruments that we currently use are forward contracts, zero-cost collars, and futures, which typically expire within one year. Valuations are based on exchange-quoted prices, which are classified as Level 1. Some of the valuations are adjusted by a forward yield curve or interest rates. In such cases, these derivative contracts are classified within Level 2. Changes in the fair market values of these contracts are recognized in the Consolidated Financial Statements as a component of cost of goods sold or foreign currency transaction (gain) loss. As of December 31, 2014 and 2013, the gross asset position of our foreign currency derivative instruments was $4.6 million and $0.6 million, respectively, and the gross liability position of our foreign currency derivative instruments was $39.8 million and $18.1 million, respectively.
	Commodity Derivatives—The commodity contracts primarily relate to natural gas. The commodity derivative instruments that we currently use are forward purchase contracts, swaps, and three-way collars. The natural gas contracts settle using NYMEX futures or AECO price indexes, which represent fair value at any given time. The contracts’ maturities are for future months and settlements are scheduled to coincide with anticipated gas purchases during those future periods. Quoted market prices from NYMEX and AECO are used to determine the fair value of these instruments. These market prices are adjusted by a forward yield curve and are classified within Level 2. Changes in the fair market values of these contracts are recognized in the Consolidated Financial Statements as a component of cost of goods sold. As of December 31, 2014 and 2013, the gross asset position of our commodity derivative instruments was $4.4 million and $6.0 million, respectively, and the gross liability position of our commodity derivative instruments was $14.9 million and $2.0 million, respectively.
	Financial Instruments
	The carrying amounts and estimated fair values of our financial instruments are as follows:
		December 31,
		2014				2013
		Carrying		Fair		Carrying		Fair
	(in millions)	Amount		Value		Amount		Value
	Cash and cash equivalents	$	2,374.60	$	2,374.60	$	5,293.10	$	5,293.10
	Accounts receivable	754.4		754.4		543.1		543.1
	Accounts payable trade	797.3		797.3		570.2		570.2
	Short-term debt	13.5		13.5		22.6		22.6
	Long-term debt, including current portion	3,819.00		4,101.20		3,009.30		3,059.60
	For cash and cash equivalents, accounts receivable, accounts payable and short-term debt, the carrying amount approximates fair value because of the short-term maturity of those instruments. The fair value of long-term debt is estimated using quoted market prices for the publicly registered notes and debentures, classified as Level 1 and Level 2, respectively, within the fair value hierarchy, depending on the market liquidity of the debt.

Guarantees_and_Indemnities

Guarantees and Indemnities	12 Months Ended
	Dec. 31, 2014
Guarantees [Abstract]
Guarantees and Indemnities	GUARANTEES AND INDEMNITIES
	We enter into various contracts that include indemnification and guarantee provisions as a routine part of our business activities. Examples of these contracts include asset purchase and sale agreements, surety bonds, financial assurances to regulatory agencies in connection with reclamation and closure obligations, commodity sale and purchase agreements, and other types of contractual agreements with vendors and other third parties. These agreements indemnify counterparties for matters such as reclamation and closure obligations, tax liabilities, environmental liabilities, litigation and other matters, as well as breaches by Mosaic of representations, warranties and covenants set forth in these agreements. In many cases, we are essentially guaranteeing our own performance, in which case the guarantees do not fall within the scope of the accounting and disclosures requirements under U.S. GAAP.
	Our more significant guarantees and indemnities are as follows:
	Guarantees to Brazilian Financial Parties. From time to time, we issue guarantees to financial parties in Brazil for certain amounts owed the institutions by certain customers of Mosaic. The guarantees are for all or part of the customers’ obligations. In the event that the customers default on their payments to the institutions and we would be required to perform under the guarantees, we have in most instances obtained collateral from the customers. We monitor the nonperformance risk of the counterparties and have noted no material concerns regarding their ability to perform on their obligations. The guarantees generally have a one-year term, but may extend up to two years or longer depending on the crop cycle, and we expect to renew many of these guarantees on a rolling twelve-month basis. As of December 31, 2014, we have estimated the maximum potential future payment under the guarantees to be $63.6 million. The fair value of our guarantees is immaterial to the Consolidated Financial Statements as of December 31, 2014 and 2013.
	Other Indemnities. Our maximum potential exposure under other indemnification arrangements can range from a specified dollar amount to an unlimited amount, depending on the nature of the transaction. Total maximum potential exposure under these indemnification arrangements is not estimable due to uncertainty as to whether claims will be made or how they will be resolved. We do not believe that we will be required to make any material payments under these indemnity provisions.
	Because many of the guarantees and indemnities we issue to third parties do not limit the amount or duration of our obligations to perform under them, there exists a risk that we may have obligations in excess of the amounts described above. For those guarantees and indemnities that do not limit our liability exposure, we may not be able to estimate what our liability would be until a claim is made for payment or performance due to the contingent nature of these arrangements. See Note 2 of our Notes to Consolidated Financial Statements for additional information for indemnification provisions related to the Cargill Transaction.

Pension_Plans_and_Other_Benefi

Pension Plans and Other Benefits	12 Months Ended
	Dec. 31, 2014
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Pension Plans And Other Benefits	PENSION PLANS AND OTHER BENEFITS
	We sponsor pension and postretirement benefits through a variety of plans including defined benefit plans, defined contribution plans, and postretirement benefit plans in North America and certain of our international locations. We reserve the right to amend, modify, or terminate the Mosaic sponsored plans at any time, subject to provisions of the Employee Retirement Income Security Act of 1974 (“ERISA”), prior agreements and our collective bargaining agreements.
	Defined Benefit and Postretirement Medical Benefit Plans
	We sponsor various defined benefit pension plans in the U.S. and in Canada. Benefits are based on different combinations of years of service and compensation levels, depending on the plan. Generally, contributions to the U.S. plans are made to meet minimum funding requirements of ERISA, while contributions to Canadian plans are made in accordance with Pension Benefits Acts instituted by the provinces of Saskatchewan and Ontario. Certain employees in the U.S. and Canada, whose pension benefits exceed Internal Revenue Code and Canada Revenue Agency limitations, respectively, are covered by supplementary non-qualified, unfunded pension plans.
	We provide certain health care benefit plans for certain retired employees (“Retiree Health Plans”) which may be either contributory or non-contributory and contain certain other cost-sharing features such as deductibles and coinsurance. The Retiree Health Plans are unfunded and the projected benefit obligation was $56.2 million and $52.8 million as of December 31, 2014 and 2013, respectively. The related income statement effects of the Retiree Health Plans are not material to the Company.
	Accounting for Pension Plans
	The year-end status of the North American pension plans was as follows:
		Pension Plans
		Year Ended December 31,				Seven Months
						Ended
						December 31,
	(in millions)	2014				2013
	Change in projected benefit obligation:
	Benefit obligation at beginning of period	$	728			$	788.6
	Service cost	6.3				4.6
	Interest cost	32.8				19
	Actuarial (gain) loss	124.8				(49.3		)
	Currency fluctuations	(26.8		)		(11.8		)
	Benefits paid	(42.1		)		(23.1		)
	Special termination costs	5.4				—
	Projected benefit obligation at end of period	$	828.4			$	728
	Change in plan assets:
	Fair value at beginning of period	$	736.9			$	707.6
	Currency fluctuations	(26.3		)		(9.1		)
	Actual return	110.7				18.8
	Company contribution	32.9				42.7
	Benefits paid	(42.1		)		(23.1		)
	Fair value at end of period	$	812.1			$	736.9
	Funded/(unfunded) status of the plans as of the end of period	$	(16.3	)		$	8.9
	Amounts recognized in the consolidated balance sheets:
	Noncurrent assets	$	10.1			$	30.2
	Current liabilities	(0.6		)		(0.6		)
	Noncurrent liabilities	(25.8		)		(20.7		)
	Amounts recognized in accumulated other comprehensive (income) loss
	Prior service costs (credits)	$	18.7			$	24.9
	Actuarial (gain) loss	120.6				73.1
	The accumulated benefit obligation for the defined benefit pension plans was $823.7 million and $724.0 million as of December 31, 2014 and 2013, respectively.
	The components of net annual periodic benefit costs and other amounts recognized in other comprehensive income include the following components:
			Pension Plans
	(in millions)		Year Ended				Seven Months Ended December 31,				Years Ended May 31,
			December 31,
	Net Periodic Benefit Cost		2014				2013				2013				2012
	Service cost		$	6.3			$	4.6			$	6.5			$	5.6
	Interest cost		32.8				19				32.6				34.5
	Expected return on plan assets		(44.0		)		(25.1		)		(37.3		)		(35.8		)
	Amortization of:
	Prior service cost/(credit)		1.9				1.4				1.3				1.3
	Actuarial (gain)/loss		4.7				5.4				16.1				13.4
	Preliminary net periodic benefit cost		$	1.7			$	5.3			$	19.2			$	19
	Curtailment expense		2.3				—				—				—
	Special termination costs		5.4				—				—				—
	Total net periodic benefit cost		$	9.4			$	5.3			$	19.2			$	19
	Other Changes in Plan Assets and Benefit
	Obligations Recognized in Other
	Comprehensive Income
	Prior service cost (credit) recognized in other comprehensive income		$	(1.9	)		$	(1.3	)		$	14.1			$	(1.3	)
	Net actuarial loss (gain) recognized in other comprehensive income		53.3				(48.5		)		(5.9		)		36.3
	Total recognized in other comprehensive income		$	51.4			$	(49.8	)		$	8.2			$	35
	Total recognized in net periodic benefit (income) cost and other comprehensive income		$	60.8			$	(44.5	)		$	27.4			$	54
	The estimated net actuarial (gain) loss and prior service cost (credit) for the pension plans and postretirement plans that will be amortized from accumulated other comprehensive income into net periodic benefit cost in calendar 2015 is $9.2 million.
	The following estimated benefit payments, which reflect estimated future service are expected to be paid by the related plans in the calendar years ending December 31:
	(in millions)	Pension Plans			Other Postretirement			Medicare Part D
		Benefit Payments			Plans Benefit Payments			Adjustments
	2015	42.2			5.8			0.6
2016	43.4			5.8			0.6
2017	44.3			5.5			0.6
2018	45.9			5.1			0.6
2019	47.3			4.5			0.6
2020-2024	247.8			16.9			1.9
In calendar 2015, we need to contribute cash of at least $14.6 million to the pension plans to meet minimum funding requirements. Also in calendar 2015, we anticipate contributing cash of $5.8 million to the postretirement medical benefit plans to fund anticipated benefit payments.
Plan Assets and Investment Strategies
The Company’s overall investment strategy is to obtain sufficient return and provide adequate liquidity to meet the benefit obligations of our pension plans. Investments are made in public securities to ensure adequate liquidity to support benefit payments. Domestic and international stocks and bonds provide diversification to the portfolio.
For the U.S. plans, we utilize an asset allocation policy that seeks to maintain a fully-funded plan status under the Pension Protection Act of 2006. As such, the primary investment objective beyond accumulating sufficient assets to meet future benefit obligations is to monitor and manage the liabilities of the plan to better insulate the portfolio from changes in interest rates that are impacting the liabilities. This requires an interest rate management strategy to reduce the sensitivity in the plan’s funded status and having a portion of the Plan’s assets invested in return-seeking strategies. Currently, our policy includes a 75% allocation to fixed income and 25% to return-seeking strategies.
For the Canadian pension plan the investment objectives for the pension plans’ assets are as follows: (i) achieve a nominal annualized rate of return equal to or greater than the actuarially assumed investment return over ten to twenty-year periods; (ii) achieve an annualized rate of return of the Consumer Price Index plus 5% over ten to twenty-year periods; (iii) realize annual, three and five-year annualized rates of return consistent with or in excess of specific respective market benchmarks at the individual asset class level; and (iv) achieve an overall return on the pension plans’ assets consistent with or in excess of the total fund benchmark, which is a hybrid benchmark customized to reflect the trusts’ asset allocation and performance objectives. Currently, our policy includes a 40% allocation to fixed income and 60% to return-seeking strategies.
A significant amount of the assets are invested in funds that are managed by a group of professional investment managers. These funds are mainly commingled funds. Performance is reviewed by Mosaic management monthly by comparing each fund’s return to benchmark with an in depth quarterly review presented by the professional investment managers to the Global Pension Investment Committee. We do not have any significant concentrations of credit risk or industry sectors within the plan assets. Assets may be indirectly invested in Mosaic stock, but any risk related to this investment would be immaterial due to the insignificant percentage of the total pension assets that would be invested in Mosaic stock.
Fair Value Measurements of Plan Assets
The following tables provide fair value measurement, by asset class of the Company’s defined benefit plan assets for both the U.S. and Canadian plans:
(in millions)	December 31, 2014
Pension Plan Assets	Total				Level 1				Level 2				Level 3
Asset Category
Cash	$	8.6			$	8.6			$	—			$	—
Equity securities(a)	302.2				—				285.9				16.3
Fixed income(b)	491.9				—				491.9				—
Private equity funds	9.4				—				—				9.4
Total assets at fair value	$	812.1			$	8.6			$	777.8			$	25.7
(in millions)	December 31, 2013
Pension Plan Assets	Total				Level 1				Level 2				Level 3
Asset Category
Cash	$	9.8			$	9.8			$	—			$	—
Equity securities(a)	281.1				—				262.8				18.3
Fixed income(b)	433.9				—				433.9				—
Private equity funds	12.1				—				—				12.1
Total assets at fair value	$	736.9			$	9.8			$	696.7			$	30.4
______________________________
(a)	This class includes several funds that are invested approximately 46% in U.S. equity securities, 26% in international equity securities, 23% in Canadian equity securities, and 5% in other real estate securities.
(b)	This class includes several funds that are invested approximately 57% in corporate debt securities, 22% in other governmental securities in the U.S. and Canada, 13% in U.S. government debt securities, 5% in foreign entity debt securities and 3% in Canadian government securities.
Rates and Assumptions
The approach used to develop the discount rate for the pension and postretirement plans is commonly referred to as the yield curve approach. Under this approach, we use a hypothetical curve formed by the average yields of available corporate bonds rated AA and above and match it against the projected benefit payment stream. Each category of cash flow of the projected benefit payment stream is discounted back using the respective interest rate on the yield curve. Using the present value of projected benefit payments, a weighted-average discount rate is derived.
The approach used to develop the expected long-term rate of return on plan assets combines an analysis of historical performance, the drivers of investment performance by asset class, and current economic fundamentals. For returns, we utilized a building block approach starting with inflation expectations and added an expected real return to arrive at a long-term nominal expected return for each asset class. Long-term expected real returns are derived in the context of future expectations of the U.S. Treasury real yield curve.
Weighted average assumptions used to determine benefit obligations were as follows:
	Pension Plans
	Year Ended			Seven Months Ended December 31,			Years Ended May 31,
	December 31,
	2014			2013			2013			2012
Discount rate	3.95	%		4.75	%		4.25	%		4.44	%
Expected return on plan assets	6.15	%		6.15	%		6.13	%		6.29	%
Rate of compensation increase	3.5	%		3.5	%		4	%		4	%
Weighted-average assumptions used to determine net benefit cost were as follows:
	Pension Plans
	Year Ended			Seven Months Ended December 31,			Years Ended May 31,
	December 31,
	2014			2013			2013			2012
Discount rate	4.75	%		4.25	%		4.44	%		5.13	%
Expected return on plan assets	6.15	%		6.13	%		6.29	%		6.87	%
Rate of compensation increase	3.5	%		4	%		4	%		4	%
Defined Contribution Plans
Eligible salaried and nonunion hourly employees in the U.S. participate in a defined contribution investment plan which permits employees to defer a portion of their compensation through payroll deductions and provides matching contributions. We match 100% of the first 3% of the participant’s contributed pay plus 50% of the next 3% of the participant’s contributed pay, subject to Internal Revenue Service limits. Participant contributions, matching contributions, and the related earnings immediately vest. Mosaic also provides an annual non-elective employer contribution feature for eligible salaried and non-union hourly employees based on the employee’s age and eligible pay. Participants are generally vested in the non-elective employer contributions after three years of service. In addition, a discretionary feature of the plan allows the Company to make additional contributions to employees. Certain union employees participate in a defined contribution retirement plan based on collective bargaining agreements.
Canadian salaried and non-union hourly employees participate in an employer funded plan with employer contributions similar to the U.S. plan. The plan provides a profit sharing component which is paid each year. We also sponsor one mandatory union plan in Canada. Benefits in these plans vest after two years of consecutive service.
The expense attributable to defined contribution plans in the U.S. and Canada was $51.5 million for calendar 2014, $30.2 million for the seven months ended December 31, 2013 and $47.3 million and $41.2 million in fiscal 2013 and 2012, respectively.

Sharebased_Payments

Share-based Payments	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Payments	SHARE-BASED PAYMENTS
	The Mosaic Company 2004 Omnibus Stock and Incentive Plan (the “Omnibus Plan”) which was approved by our shareholders and became effective October 20, 2004 and subsequently amended, provides for the grant of shares and share options to employees for up to 25 million shares of common stock. Following the effectiveness of The Mosaic Company 2014 Stock and Incentive Plan (the "2014 Stock and Incentive Plan") as described below, no additional awards were granted under the Omnibus Plan, but the Omnibus Plan will remain in effect with respect to the awards that had previously been granted thereunder.
	The Mosaic Company 2014 Stock and Incentive Plan (the "2014 Stock and Incentive Plan") was approved by our shareholders and became effective on May 15, 2014 and permits the grant of stock and stock options to employees for up to 25 million shares of common stock. The 2014 Stock and Incentive Plan provides for grants of stock options, restricted stock, restricted stock units, performance units and a variety of other share-based and non-share-based awards. Our employees, officers, directors, consultants, agents, advisors, and independent contractors, as well as other designated individuals, are eligible to participate in the 2014 Stock and Incentive Plan.
	Mosaic settles stock option exercises, restricted stock units and performance units with newly issued common shares. The Compensation Committee of the Board of Directors administers the 2014 Stock and Incentive Plan and the Omnibus Plan subject to their respective provisions and applicable law.
	Stock Options
	Stock options are granted with an exercise price equal to the market price of our stock at the date of grant and have a ten-year contractual term. The fair value of each option award is estimated on the date of the grant using the Black-Scholes option valuation model. Stock options vest in equal annual installments in the first three years following the date of grant (graded vesting). Stock options are expensed on a straight-line basis over the required service period, based on the estimated fair value of the award on the date of grant, net of estimated forfeitures.
	Valuation Assumptions
	Assumptions used to calculate the fair value of stock options in each period are noted in the following table. Expected volatility is based on the simple average of implied and historical volatility using the daily closing prices of the Company’s stock for a period equal to the expected term of the option. The risk-free interest rate is based on the U.S. Treasury rate at the time of the grant for instruments of comparable life.
		Year Ended		Seven Months Ended December 31,		Years Ended May 31,
		December 31,
		2014		2013		2013		2012
	Weighted average assumptions used in option valuations:
	Expected volatility	42.4	%	43.87	%	47.7	%	51.8	%
	Expected dividend yield	2.01	%	1.85	%	1.74	%	0.28	%
	Expected term (in years)	7		7		7		5
	Risk-free interest rate	2.31	%	1.99	%	0.92	%	1.46	%
	A summary of the status of our stock options as of December 31, 2014, and activity during the calendar year 2014, is as follows:
		Shares		Weighted			Weighted Average Remaining Contractual Term (Years)	Aggregate
		(in millions)		Average				Intrinsic
				Exercise				Value
				Price
	Outstanding as of December 31, 2013	2.6		$	44.82		5	$	28
	Granted	0.2		$	49.73
	Exercised	(0.4	)	$	18.91
	Outstanding as of December 31, 2014	2.4		$	48.88		4.8	$	16
	Exercisable as of December 31, 2014	2		$	48.16		4	$	16
	The weighted-average grant date fair value of options granted during calendar 2014 was $18.79, $20.87 during the seven months ended December 31, 2013, and $22.71 and $30.96 during fiscal 2013 and 2012, respectively. The total intrinsic value of options exercised during calendar 2014 was $9.4 million, during the seven months ended December 31, 2013 was $1.3 million and during fiscal 2013 and 2012 was $6.8 million and $5.5 million, respectively.
	Restricted Stock Units
	Restricted stock units are issued to various employees, officers and directors at a price equal to the market price of our stock at the date of grant. The fair value of restricted stock units is equal to the market price of our stock at the date of grant. Restricted stock units generally cliff vest after three years of continuous service and are expensed on a straight-line basis over the required service period, based on the estimated grant date fair value, net of estimated forfeitures.
	A summary of the status of our restricted stock units as of December 31, 2014, and activity during calendar 2014, is as follows:
		Shares		Weighted
		(in millions)		Average
				Grant
				Date Fair
				Value Per
				Share
	Restricted stock units as of December 31, 2013	0.8		$	57.5
	Granted	0.6		48.72
	Issued and cancelled	(0.4	)	55.51
	Restricted stock units as of December 31, 2014	1		$	53.12
	Performance Units
	During the year ended December 31, 2014, approximately 100,000 performance units were granted with a weighted average grant date fair value of $61.11. Final performance units are awarded based on the increase or decrease, subject to certain limitations, in Mosaic’s share price from the grant date to the third anniversary of the award, plus dividends. The beginning and ending stock prices are based on a 30 trading-day average stock price. Holders of the awards must be employed at the end of the performance period in order for any shares to vest, except in the event of death, disability or retirement at or after age 60, certain changes in control, and Committee or Board discretion as provided in the related award agreements.
	The fair value of each performance unit is determined using a Monte Carlo simulation. This valuation methodology utilizes assumptions consistent with those of our other share-based awards and a range of ending stock prices; however, the expected term of the awards is three years, which impacts the assumptions used to calculate the fair value of performance units as shown in the table below. Performance units are considered equity-classified fixed awards measured at grant-date fair value and not subsequently re-measured. Performance units cliff vest after three years of continuous service. Performance units are expensed on a straight-line basis over the required service period, based on the estimated grant date fair value of the award net of estimated forfeitures.
	A summary of the assumptions used to estimate the fair value of performance units is as follows:
		Year Ended		Seven Months Ended December 31,		Years Ended May 31,
		December 31,
		2014		2013		2013		2012
	Weighted average assumptions used in performance unit valuations:
	Expected volatility	30.39	%	32.78	%	38.05	%	54.72	%
	Expected dividend yield	2.08	%	1.85	%	1.74	%	0.28	%
	Expected term (in years)	3		3		3		3
	Risk-free interest rate	0.77	%	0.61	%	0.31	%	0.69	%
	A summary of our performance unit activity during calendar 2014 is as follows:
		Shares		Weighted
		(in  millions)		Average
				Grant
				Date Fair
				Value Per
				Share
	Outstanding as of December 31, 2013	0.4		$	69.64
	Granted	0.1		61.11
	Outstanding as of December 31, 2014	0.5		$	64.31
	We recorded share-based compensation expense of $57.2 million for calendar 2014, $25.1 million for the seven months ended December 31, 2013, $32.2 million for fiscal 2013 and $25.2 million for fiscal 2012. The tax benefit related to share-based compensation expense was $19.8 million for calendar 2014, $8.4 million for the seven months ended December 31, 2013, $11.4 million for fiscal 2013 and $8.7 million for fiscal 2012.
	As of December 31, 2014, there was $31.6 million of total unrecognized compensation cost related to options, restricted stock units and performance units granted under the 2014 Stock and Incentive Plan and the Omnibus Plan. The unrecognized compensation cost is expected to be recognized over a weighted-average period of 1 year. The total fair value of options vested in calendar 2014, the seven months ended December 31, 2013 and fiscal 2013 and 2012 was $5.5 million, $7.1 million, $9.5 million and $10.2 million, respectively.
Cash received from exercises of all share-based payment arrangements for calendar 2014, the seven months ended December 31, 2013, fiscal 2013 and 2012 was $6.7 million, $1.1 million, $6.0 million and $3.0 million, respectively. In calendar 2014, the seven months ended December 31, 2013, fiscal 2013 and 2012 we received a tax benefit for tax deductions from options of $10.2 million, $4.4 million, $6.4 million, and $3.7 million, respectively.

Commitments

Commitments	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments	COMMITMENTS
	We lease certain plants, warehouses, terminals, office facilities, railcars and various types of equipment under operating leases, some of which include rent payment escalation clauses, with lease terms ranging from one to ten years. In addition to minimum lease payments, some of our office facility leases require payment of our proportionate share of real estate taxes and building operating expenses.
	We have long-term agreements for the purchase of sulfur which is used in the production of phosphoric acid. In addition, we have long-term agreements for the purchase of raw materials, including a commercial offtake agreement with the Miski Mayo Mine for phosphate rock and an agreement with CF for the purchase of ammonia, used to produce phosphate products. We have long-term agreements for the purchase of natural gas, which is a significant raw material, used primarily in the solution mining process in our Potash segment and used in our phosphate concentrates plants. Also, we have agreements for capital expenditures primarily in our Potash segments related to our expansion projects.
	A schedule of future minimum long-term purchase commitments, based on December 31, 2014 market prices, and minimum lease payments under non-cancelable operating leases as of December 31, 2014 follows:
	(in millions)	Purchase		Operating
		Commitments		Leases
	2015	$	2,420.60	$	58
	2016	532.4		50.1
	2017	422.1		43.9
	2018	364.9		34.5
	2019	366		29.1
	Subsequent years	4,189.40		90.6
		$	8,295.40	$	306.2
	Rental expense for calendar 2014, seven months ended December 31, 2013, fiscal 2013 and 2012 amounted to $108.9 million, $56.5 million, $88.8 million and $80.0 million, respectively. Purchases made under long-term commitments were $2.3 billion for calendar 2014, $1.2 billion for the seven months ended December 31, 2013 and $2.7 billion and $3.1 billion for fiscal 2013 and 2012, respectively.
	Most of our export sales of potash crop nutrients are marketed through a North American export association, Canpotex, which may fund its operations in part through third-party financing facilities. As a member, Mosaic or our subsidiaries are contractually obligated to reimburse Canpotex for their pro rata share of any operating expenses or other liabilities incurred. The reimbursements are made through reductions to members’ cash receipts from Canpotex.
	We incur liabilities for reclamation activities and Gypstack closures in our Florida and Louisiana operations where, in order to obtain necessary permits, we must either pass a test of financial strength or provide credit support, typically in the form of cash deposits, surety bonds or letters of credit. The surety bonds generally expire within one year or less but a substantial portion of these instruments provide financial assurance for continuing obligations and, therefore, in most cases, must be renewed on an annual basis. As of December 31, 2014, we had $179.9 million in surety bonds outstanding, of which $170.1 million is for reclamation obligations, primarily related to mining in Florida, and $9.8 million is for other matters.

Contingencies

Contingencies	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Contingencies	CONTINGENCIES
	We have described below judicial and administrative proceedings to which we are subject.
	We have contingent environmental liabilities that arise principally from three sources: (i) facilities currently or formerly owned by our subsidiaries or their predecessors; (ii) facilities adjacent to currently or formerly owned facilities; and (iii) third-party Superfund or state equivalent sites. At facilities currently or formerly owned by our subsidiaries or their predecessors, the historical use and handling of regulated chemical substances, crop and animal nutrients and additives and by-product or process tailings have resulted in soil, surface water and/or groundwater contamination. Spills or other releases of regulated substances, subsidence from mining operations and other incidents arising out of operations, including accidents, have occurred previously at these facilities, and potentially could occur in the future, possibly requiring us to undertake or fund cleanup or result in monetary damage awards, fines, penalties, other liabilities, injunctions or other court or administrative rulings. In some instances, pursuant to consent orders or agreements with governmental agencies, we are undertaking certain remedial actions or investigations to determine whether remedial action may be required to address contamination. At other locations, we have entered into consent orders or agreements with appropriate governmental agencies to perform required remedial activities that will address identified site conditions. Taking into consideration established accruals of approximately $32.5 million and $31.3 million, as of December 31, 2014 and December 31, 2013, respectively, expenditures for these known conditions currently are not expected, individually or in the aggregate, to have a material effect on our business or financial condition. However, material expenditures could be required in the future to remediate the contamination at known sites or at other current or former sites or as a result of other environmental, health and safety matters. Below is a discussion of the more significant environmental matters.
	EPA RCRA Initiative. In 2003, the U.S. Environmental Protection Agency (“EPA”) Office of Enforcement and Compliance Assurance announced that it would be targeting facilities in mineral processing industries, including phosphoric acid producers, for a thorough review under the U.S. Resource Conservation and Recovery Act (“RCRA”) and related state laws. Mining and processing of phosphates generate residual materials that must be managed both during the operation of a facility and upon a facility’s closure. Certain solid wastes generated by our phosphate operations may be subject to regulation under RCRA and related state laws. The EPA rules exempt “extraction” and “beneficiation” wastes, as well as 20 specified “mineral processing” wastes, from the hazardous waste management requirements of RCRA. Accordingly, certain of the residual materials which our phosphate operations generate, as well as process wastewater from phosphoric acid production, are exempt from RCRA regulation. However, the generation and management of other solid wastes from phosphate operations may be subject to hazardous waste regulation if the waste is deemed to exhibit a “hazardous waste characteristic.” As part of its initiative, we understand that EPA has inspected all or nearly all facilities in the U.S. phosphoric acid production sector to ensure compliance with applicable RCRA regulations and to address any “imminent and substantial endangerment” found by the EPA under RCRA. We have provided the EPA with substantial amounts of information regarding the process water recycling practices and the hazardous waste handling practices at our phosphate production facilities in Florida and Louisiana, and the EPA has inspected all of our currently operating processing facilities in the U.S. In addition to the EPA’s inspections, our phosphates concentrates facilities have entered into consent orders to perform analyses of existing environmental data, to perform further environmental sampling as may be necessary, and to assess whether the facilities pose a risk of harm to human health or the surrounding environment.
	We have received Notices of Violation (“NOVs”) from the EPA related to the handling of hazardous waste at our Riverview (September 2005), New Wales (October 2005), Mulberry (June 2006), Green Bay (August 2006) and Bartow (September 2006) facilities in Florida. The EPA issued similar NOVs to our competitors, including with respect to the Plant City Facility acquired in the CF Phosphate Assets Acquisition as described in Note 23, and referred the NOVs to the U.S. Department of Justice (“DOJ”) for further enforcement. We currently are engaged in discussions with the DOJ and EPA with respect to our facilities (excluding the Plant City Facility). We believe we have substantial defenses to the allegations in the NOVs, including but not limited to previous EPA regulatory interpretations and inspection reports finding that the process water handling practices in question comply with the requirements of the exemption for extraction and beneficiation wastes. We intend to evaluate various alternatives and continue discussions to determine if a negotiated resolution can be reached. If it cannot, we intend to vigorously defend these matters in any enforcement actions that may be pursued.
	We are negotiating the terms of a possible settlement with the EPA, the DOJ, the Florida Department of Environmental Protection and the Louisiana Department of Environmental Quality (collectively, the “Government”) and the final terms are not yet agreed upon or approved. If a settlement can be achieved, in all likelihood our commitments would be multi-faceted with key elements including, in general and among other elements, the following:
	•	Incurring future capital expenditures likely to exceed $150 million in the aggregate over a period of several years.
	•	Providing meaningful additional financial assurance for the estimated costs of closure and post-closure care (“Gypstack Closure Costs”) of our phosphogypsum management systems ("Gypstacks"). For financial reporting purposes, we recognize our estimated ARO, including Gypstack Closure Costs, at their present value. This present value determined for financial reporting purposes is reflected on our Consolidated Balance Sheets in accrued liabilities and other noncurrent liabilities. As of December 31, 2014, the undiscounted amount of our Gypstack AROs, determined using the assumptions used for financial reporting purposes, was approximately $1.7 billion and the present value of our Gypstack Closure Costs reflected in our Consolidated Balance Sheet was approximately $543 million. Currently, financial assurance requirements in Florida and Louisiana for Gypstack Closure Costs can be satisfied through a variety of methods, including satisfaction of financial tests. In the context of a potential settlement of the Government’s enforcement action, we expect that we would agree to pre-fund a material portion of our Gypstack Closure Costs, primarily by depositing cash, currently estimated to be in the amount of approximately $625 million, into one or more trust funds which would increase over time with reinvestment of earnings. Amounts held in any such trust funds (including reinvested earnings) would be classified as restricted cash included in other assets on our Consolidated Balance Sheets. We expect that any final settlement of this matter would resolve substantially all of our financial assurance obligations to the Government for Gypstack Closure Costs. Our actual Gypstack Closure Costs are generally expected to be paid by us in the normal course of our Phosphates business over a period that may not end until three decades or more after a Gypstack has been closed.
	•	We have also established accruals to address the estimated cost of civil penalties in connection with this matter, which we do not believe, in light of the relevant regulatory history, would be material to our results of operations, liquidity or capital resources.
	In light of our strong operating cash flows, liquidity and capital resources, we believe that we have sufficient liquidity and capital resources to be able to fund such capital expenditures, financial assurance requirements and civil penalties as part of a settlement. If a settlement cannot be agreed upon, we cannot predict the outcome of any litigation or estimate the potential amount or range of loss; however, we would face potential exposure to material costs should we fail in the defense of an enforcement action.
	See Note 23 for a discussion of how the EPA's RCRA Initiative and Florida financial assurance requirements affect the facilities we acquired in the CF Phosphate Assets Acquisition.
	EPA EPCRA Initiative. In July 2008, the DOJ sent a letter to major U.S. phosphoric acid manufacturers, including us, stating that the EPA’s ongoing investigation indicates apparent violations of Section 313 of the Emergency Planning and Community Right-to-Know Act (“EPCRA”) at their phosphoric acid manufacturing facilities. Section 313 of EPCRA requires annual reports to be submitted with respect to the use or presence of certain toxic chemicals. DOJ and EPA also stated that they believe that a number of these facilities have violated Section 304 of EPCRA and Section 103 of the Comprehensive Environmental Response, Compensation and Liability Act ("CERCLA") by failing to provide required notifications relating to the release of hydrogen fluoride from the facilities. The letter did not identify any specific violations by us or assert a demand for penalties against us. We cannot predict at this time whether the EPA and DOJ will initiate an enforcement action over this matter, what its scope would be, or what the range of outcomes of such a potential enforcement action might be.
	Florida Sulfuric Acid Plants. On April 8, 2010, the EPA Region 4 submitted an administrative subpoena to us under Section 114 of the Federal Clean Air Act (the “CAA”) regarding compliance of our Florida sulfuric acid plants with the “New Source Review” requirements of the CAA. The request received by Mosaic appears to be part of a broader EPA national enforcement initiative focusing on sulfuric acid plants. We cannot predict at this time whether the EPA and DOJ will initiate an enforcement action over this matter, what its scope would be, or what the range of outcomes of such a potential enforcement action might be.
	Other Environmental Matters. Superfund and equivalent state statutes impose liability without regard to fault or to the legality of a party’s conduct on certain categories of persons who are considered to have contributed to the release of “hazardous substances” into the environment. Under Superfund, or its various state analogues, one party may, under certain circumstances, be required to bear more than its proportionate share of cleanup costs at a site where it has liability if payments cannot be obtained from other responsible parties. Currently, certain of our subsidiaries are involved or concluding involvement at several Superfund or equivalent state sites. Our remedial liability from these sites, alone or in the aggregate, currently is not expected to have a material effect on our business or financial condition. As more information is obtained regarding these sites and the potentially responsible parties involved, this expectation could change.
	We believe that, pursuant to several indemnification agreements, our subsidiaries are entitled to at least partial, and in many instances complete, indemnification for the costs that may be expended by us or our subsidiaries to remedy environmental issues at certain facilities. These agreements address issues that resulted from activities occurring prior to our acquisition of facilities or businesses from parties including, but not limited to, ARCO (BP); Beatrice Fund for Environmental Liabilities; Conoco; Conserv; Estech, Inc.; Kaiser Aluminum & Chemical Corporation; Kerr-McGee Inc.; PPG Industries, Inc.; The Williams Companies; CF; and certain other private parties. Our subsidiaries have already received and anticipate receiving amounts pursuant to the indemnification agreements for certain of their expenses incurred to date as well as future anticipated expenditures. We record potential indemnifications as an offset to the established accruals when they are realizable or realized.
	MicroEssentials® Patent Lawsuit
	On January 9, 2009, John Sanders and Specialty Fertilizer Products, LLC filed a complaint against Mosaic, Mosaic Fertilizer, LLC, Cargill, Incorporated and Cargill Fertilizer, Inc. in the United States District Court for the Western District of Missouri (the “Missouri District Court”). The complaint alleges that our production of MicroEssentials® SZ, one of several types of the MicroEssentials® value-added ammoniated phosphate crop nutrient products that we produce, infringes on a patent then held by the plaintiffs. Plaintiffs have since asserted that other MicroEssentials® products also infringe the patent. Plaintiffs seek to enjoin the alleged infringement and to recover an unspecified amount of damages and attorneys’ fees for past infringement. Our answer to the complaint responds that the plaintiffs’ patent is not infringed, is invalid and is unenforceable because the plaintiffs engaged in inequitable conduct during the prosecution of the patent.
	The Missouri District Court stayed the lawsuit pending an ex parte reexamination of plaintiffs’ patent claims by the U.S. Patent and Trademark Office (the “PTO”). That ex parte reexamination has now ended, with different patent claims being granted to the plaintiffs. On September 12, 2012, however, Shell Oil Company (“Shell”) filed an additional reexamination request which in part asserted that the claims as amended and added in connection with the ex parte reexamination are unpatentable. On October 4, 2012, the PTO issued an Ex Parte Reexamination Certificate in which certain claims of the plaintiffs’ patent were cancelled, disclaimed and amended, and new claims were added. Following the PTO’s grant of Shell’s request for an inter parties reexamination, on December 11, 2012, the PTO issued an initial rejection of all of plaintiffs’ remaining patent claims. On September 12, 2013, the PTO reversed its initial rejection of the plaintiffs’ remaining patent claims and allowed them to stand. Shell has appealed the PTO’s decision. A successful appeal by Shell could limit or eliminate the claims the plaintiffs can assert against us.
	Through an order entered by the court on September 25, 2014, Cargill was dismissed as a defendant, and the two original plaintiffs were replaced by JLSMN LLC, an entity to whom the patents were transferred.
	We believe that the plaintiffs’ allegations are without merit and intend to defend vigorously against them. At this stage of the proceedings, we cannot predict the outcome of this litigation, estimate the potential amount or range of loss or determine whether it will have a material effect on our results of operations, liquidity or capital resources.
	Brazil Tax Contingencies
	Our Brazilian subsidiary is engaged in a number of judicial and administrative proceedings relating to various non-income tax matters. We estimate that our maximum potential liability with respect to these matters is approximately $91 million. Approximately $50 million of the maximum potential liability relates to PIS and Cofins tax credit cases for the period from 2004 to 2009; while the majority of the remaining amount relates to various other non-income tax cases such as value-added taxes. Based on Brazil legislation and the current status of similar tax cases involving unrelated taxpayers, we believe we have recorded adequate accruals, which are immaterial, for the probable liability with respect to these Brazilian judicial and administrative proceedings.
	Other Claims
	We also have certain other contingent liabilities with respect to judicial, administrative and arbitration proceedings and claims of third parties, including tax matters, arising in the ordinary course of business. We do not believe that any of these contingent liabilities will have a material adverse impact on our business or financial condition, results of operations, and cash flows.

Related_Party_Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2014
Related Party Transactions [Abstract]
Related Party Transactions	RELATED PARTY TRANSACTIONS
	We enter into transactions and agreements with certain of our non-consolidated companies from time to time. As of December 31, 2014 and 2013, the net amount due from our non-consolidated companies totaled $35.7 million and $52.6 million, respectively.
	The Consolidated Statements of Earnings included the following transactions with our non-consolidated companies:
		Year Ended		Seven Months Ended December 31,
		December 31,				Years Ended May 31,
	(in millions)	2014		2013		2013		2012
	Transactions with non-consolidated companies included in net sales	$	946	$	448.8	$	1,263.90	$	1,321.20
	Transactions with non-consolidated companies included in cost of goods sold	532.8		257.5		632		557.3

Disposal_and_Exit_Activities

Disposal and Exit Activities	12 Months Ended
	Dec. 31, 2014
Restructuring and Related Activities [Abstract]
Disposal and Exit Activities	DISPOSAL AND EXIT ACTIVITIES
	In 2013, we decided to exit our distribution businesses in Argentina and Chile and in connection with this decision, we wrote down the related assets by approximately $50 million, pre-tax, to their estimated fair value. This amount was included in loss on write down of assets in the Consolidated Statement of Earnings in our Transition Report on Form 10-K filed with the SEC for the transition period from June 1, 2013 to December 31, 2013 (the "2013 10-K Report"). As a result of new information regarding the structure of the intended disposition of Argentina’s distribution business as an asset sale, during the twelve months ended December 31, 2014, we recorded a $53.6 million tax benefit. In the fourth quarter of 2014, we completed the sale of our Argentina assets and recorded a pre-tax gain of $8.5 million. Additionally, the decision was made in the second quarter of 2014 to close the Chile business and sell the remaining fixed assets. We recorded a pre-tax loss of $5.6 million related to the decision. The fixed assets related to Chile’s distribution businesses qualify for asset held for sale accounting. At December 31, 2014, we included $6.0 million in other current assets in our Condensed Consolidated Balance Sheet as assets held for sale. We expect to continue to sell our products in these countries by using other distribution channels. Completion of these exit activities is expected during the first half of 2015.
	In 2013, we also decided to sell the salt operations of our Hersey, Michigan mine and close the related potash operations. In connection with the planned sale of this mine, we wrote down the related assets by approximately $48 million pre-tax, to their estimated fair value during the three months ended September 30, 2013, and recorded a corresponding tax benefit of approximately $17 million, which was reflected in the Consolidated Statement of Earnings in our 2013 10-K Report. The sale of the salt operations was completed on July 29, 2014 for $55.0 million, resulting in a pre-tax gain of $13.5 million in calendar 2014.
	On July 21, 2014, we decided to permanently discontinue production of MOP at our Carlsbad, New Mexico facility. The final date for production was December 28, 2014. The decision was based on the quality of the ore in the Carlsbad basin and the age of the facility’s infrastructure. Our larger potash production facilities at Esterhazy, Belle Plaine and Colonsay in Saskatchewan, Canada will continue to produce MOP.
	We plan to transition the Carlsbad facility to exclusive production of our highly valued K-Mag® product line. The pre-tax charges were $125.4 million, of which approximately $100 million related to accelerated depreciation and depletion in calendar 2014. We also recorded a tax benefit of approximately $52 million related to these costs in the year ended December 31, 2014.
	During calendar 2014, we recorded severance charges and other personnel related costs of approximately $11 million in connection with the previously announced closing of our Hookers Prairie phosphate mine and certain cost saving initiatives. During calendar 2014, we paid approximately $9 million related to these costs, with the remaining amounts to be paid by March 31, 2015.

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2014
Business Combinations [Abstract]
Acquisitions	ACQUISITIONS
	CF Acquisition
	On March 17, 2014, we completed the CF Phosphate Assets Acquisition. The purchase price was $1,172.1 million plus an additional $203.7 million (all in cash) to fund CF’s asset retirement obligation trust and escrow. We acquired CF's phosphate mining and production operations in Central Florida and terminal and warehouse facilities in Tampa, Florida. This acquisition allows us to take advantage of synergies associated with combining our phosphate operations and logistical capabilities in Central Florida with those of CF. In addition, we will be able to forego the construction of a beneficiation plant at Ona and the construction of an ammonia plant. The results of the CF phosphates operations have been included in our condensed consolidated financial statements for the period from March 17, 2014 through December 31, 2014.
	As part of the CF Phosphate Assets Acquisition, we assumed certain ARO related to Gypstack Closure Costs at both the Plant City, Florida phosphate concentrates facility (the "Plant City Facility") and a closed Florida phosphate concentrates facility in Bartow, Florida (the “Bonnie Facility”) that we acquired. Associated with these assets are two related financial assurance arrangements for which we became responsible and that place into trust the estimated Gypstack Closure Costs for these facilities, pursuant to federal or state law, which the government can draw against in the event we cannot perform such closure activities. One is a trust (the “Plant City Trust”) established to meet the requirements under a consent decree with the EPA and the FDEP with respect to RCRA compliance at Plant City (the “Plant City Consent Decree”) that also satisfies Florida financial assurance requirements at that site. The other is a trust fund (the “Bonnie Facility Trust”) established to meet the requirements under Florida financial assurance regulations (the “Florida Financial Assurance Requirement”) that apply to the Bonnie Facility. In the CF Phosphate Assets Acquisition, we deposited $189.2 million into the Plant City Trust as a substitute for funds that CF had deposited into trust. Based on our most recent closure cost estimates, an additional $7 million was added to the Plant City Trust in the fourth quarter of 2014 to attain full funding status. In addition, in July 2014, the FDEP approved our funding of $14.5 million into the Bonnie Facility Trust, which substituted funds that CF had deposited into an escrow account. We expect we will be required to deposit up to an additional $4 million in the Bonnie Facility Trust near the end of 2015. Both financial assurance funding obligations require estimates of future expenditures that could be impacted by refinements in scope, technological developments, cost inflation, changes in regulations, discount rates and the timing of activities. Additional funding would be required in the future if increases in cost estimates exceed investment earnings in the Plant City Trust or the Bonnie Facility Trust. The deposits into the Plant City Trust and the Bonnie Facility Trust are reflected in the Statement of Cash Flows components of the $1,375.8 million cash used in the CF Phosphate Assets Acquisition.
	At December 31, 2014, the aggregate amount of AROs associated with the Plant City Facility and the Bonnie Facility included in our consolidated balance sheet was $103.5 million. The aggregate amount held in the Plant City Trust and the Bonnie Facility Trust exceeds the aggregate amount of AROs associated with the Plant City Facility and the Bonnie Facility because the amount required to be held in the Plant City Trust represents the aggregate undiscounted estimated amount to be paid by us in the normal course of our Phosphates business over a period that may not end until three decades or more after the Gypstack has been closed, while the ARO included in our Consolidated Balance Sheet reflect the discounted present value of those estimated amounts. As part of the acquisition we also acquired ARO related to land reclamation.
	The following table summarizes the amounts of the assets acquired and liabilities assumed as recognized with the acquisition.
	(in millions)
	Inventory	$	144.1
	Other current assets	0.5
	Mineral properties and rights	499.7
	Property, plant and equipment	627.1
	Funds in trust for asset retirement obligations (1)	203.7
	Other assets	56.8
	Current liabilities	(1.5		)
	Other liabilities	(9.0		)
	Asset retirement obligation	(145.6		)
	Total purchase price paid	$	1,375.80
	(1) Included with other assets in the Consolidated Balance Sheet as of December 31, 2014
	We also signed two strategic supply agreements with CF under which CF will provide Mosaic with ammonia for its production purposes (“CF Ammonia Supply Agreements”). Under one agreement, which is expected to commence prior to January 1, 2017, Mosaic will purchase approximately 545,000 to 725,000 tonnes annually for up to fifteen years at a price tied to the prevailing price of U.S. natural gas. The execution of this agreement was not contingent upon the completion of the acquisition; therefore, no corresponding asset or liability was recorded as part of the acquisition accounting.
	Under the second agreement, which became effective on the acquisition date, Mosaic will purchase approximately 270,000 tonnes annually for three years from CF’s Trinidad operations at CFR Tampa market-based pricing.  The effectiveness of this agreement was a condition to the acquisition and included in the acquisition accounting, but its impacts were not material.
	We recognized approximately $8.7 million of acquisition and integration costs that were expensed during 2014. These costs are included within selling, general and administrative expenses in the Consolidated Statements of Earnings.
	The CF phosphates operations contributed revenues of $574.2 million and net earnings of $37.6 million from March 17, 2014 through December 31, 2014, excluding the effects of the acquisition and integration costs described above.
	Brazil and Paraguay Distribution Business Acquisition
	On December 17, 2014, we completed the acquisition of ADM's fertilizer distribution business and working capital in Brazil and Paraguay for approximately $350 million, including a target working capital amount of $150 million, which was funded with cash from operations. This acquisition is expected to significantly accelerate our previously announced growth plans in Brazil as well as replace a substantial amount of planned internal investments in that country. Under the terms of the agreements, we acquired four blending and warehousing facilities in Brazil, one in Paraguay and additional warehousing and logistics service capabilities. We expect this acquisition to increase our annual distribution in the region from approximately four million metric tonnes to about six million metric tonnes of crop nutrients.
	The parties have also entered into five-year fertilizer supply agreements providing for Mosaic to supply ADM’s fertilizer needs in Brazil and Paraguay.
	The following table summarizes the amounts of the assets acquired and liabilities assumed as recognized at the acquisition date. The fair value of these assets and liabilities is provisional pending determination of the final valuation:
	(in millions)
	Inventory	$	122.5
	Other current assets	10.3
	Property, plant and equipment	95.1
	Goodwill	105.9
	Other assets	18.6
	Accounts payable	(19.2		)
	Other current liabilities	(24.2		)
	Estimated value of acquisition	$	309
	Estimated post closing working capital adjustment	$	40.6
	Initial payment for acquisition	$	349.6
	We recognized approximately $2.9 million of acquisition and integration costs that were expensed during 2014. These costs are included within selling, general and administrative expenses in the Consolidated Statements of Earnings.
	The contribution from this additional distribution business in Brazil and Paraguay to our revenues and net earnings was immaterial for the period December 17, 2014 through December 31, 2014.
	Pro-forma Results
	The unaudited pro-forma consolidated results presented below include the effects of the acquisitions described above as if they had been consummated as of January 1, 2013. The pro-forma results below include adjustments related to depreciation and amortization to reflect the fair value of acquired property, plant and equipment and identifiable intangible assets, depletion of acquired mineral rights, and the associated income tax impacts. The pro-forma information does not necessarily reflect the actual results of operations had the acquisitions been consummated at the beginning of the fiscal reporting period indicated nor is it indicative of future operating results. The pro-forma information does not include any adjustment for potential revenue enhancements, cost synergies or other operating efficiencies that could result from the acquisition or transaction or integration costs relating to the acquisitions.
		(in millions)	Years Ended
			December 31,
			2014		2013
		Net sales	$	9,947.70	$	10,820.90
		Net earnings attributable to Mosaic	$	1,014.60	$	1,079.80

Business_Segments

Business Segments	12 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
Business Segments	BUSINESS SEGMENTS
	The reportable segments are determined by management based upon factors such as products and services, production processes, technologies, market dynamics, and for which segment financial information is available for our chief operating decision maker.
	For a description of our business segments see Note 1 of our Notes to Consolidated Financial Statements. We evaluate performance based on the operating earnings of the respective business segments, which includes certain allocations of corporate selling, general and administrative expenses. The segment results may not represent the actual results that would be expected if they were independent, stand-alone businesses. Corporate, Eliminations and Other primarily represents unallocated corporate office activities and eliminations. All intersegment transactions are eliminated within Corporate, Eliminations and other.
	Segment information for calendar 2014, the seven months ended December 31, 2013, and fiscal 2013 and 2012 is as follows:
	(in millions)		Phosphates				Potash			Corporate,				Total
										Eliminations
										and Other
	Year Ended December 31, 2014
	Net sales to external customers		$	6,194.00			$	2,839.90		$	21.9			$	9,055.80
	Intersegment net sales		—				11.7			(11.7		)		—
	Net sales		6,194.00				2,851.60			10.2				9,055.80
	Gross margin		1,071.20				897.7			(42.3		)		1,926.60
	Carlsbad restructuring expense		—				125.4			—				125.4
	Operating earnings (loss)		766.7				630.6			(85.5		)		1,311.80
	Capital expenditures		439				470.7			19.4				929.1
	Depreciation, depletion and amortization expense		368.9				355.1			26.9				750.9
	Equity in net earnings (loss) of nonconsolidated companies		(4.6		)		—			2.4				(2.2		)
	Seven Months Ended December 31, 2013
	Net sales to external customers		$	3,438.20			$	1,323.90		$	3.8			$	4,765.90
	Intersegment net sales		—				63.3			(63.3		)		—
	Net sales		3,438.20				1,387.20			(59.5		)		4,765.90
	Gross margin		445				374.3			9				828.3
	Operating earnings (loss)		199.7				224.6			(7.4		)		416.9
	Capital expenditures		298.7				471			30.3				800
	Depreciation, depletion and amortization expense		177.2				197.2			11.8				386.2
	Equity in net earnings of nonconsolidated companies		10.1				—			0.8				10.9
	Year Ended May 31, 2013
	Net sales to external customers		$	6,494.60			$	3,469.10		$	10.4			$	9,974.10
	Intersegment net sales		—				60.2			(60.2		)		—
	Net sales		6,494.60				3,529.30			(49.8		)		9,974.10
	Gross margin		1,162.20				1,611.30			(13.3		)		2,760.20
	Operating earnings (loss)		848.1				1,393.00			(31.5		)		2,209.60
	Capital expenditures		427.5				1,017.70			143.1				1,588.30
	Depreciation, depletion and amortization expense		287.3				301.9			15.6				604.8
	Equity in net earnings of nonconsolidated companies		16.4				—			1.9				18.3
	Year Ended May 31, 2012
	Net sales to external customers		$	7,839.20			$	3,263.10		$	5.5			$	11,107.80
	Intersegment net sales		—				38.2			(38.2		)		—
	Net sales		7,839.20				3,301.30			(32.7		)		11,107.80
	Gross margin		1,466.90				1,622.00			(3.9		)		3,085.00
	Operating earnings (loss)		1,179.10				1,457.30			(25.3		)		2,611.10
	Capital expenditures		407.9				1,171.40			60				1,639.30
	Depreciation, depletion and amortization expense		263.9				233.1			11.1				508.1
	Equity in net earnings of nonconsolidated companies		11.9				—			1.4				13.3
	Total assets as of December 31, 2014		$	11,392.20			$	8,296.60		$	(1,405.8	)		$	18,283.00
	Total assets as of December 31, 2013		9,945.10				9,597.40			11.5				19,554.00
	Financial information relating to our operations by geographic area is as follows:
		Year Ended				Seven Months Ended December 31,			Years Ended May 31,
		December 31,
	(in millions)	2014				2013			2013				2012
	Net sales(a):
	Brazil	$	1,921.40			$	1,249.80		$	2,069.30			$	2,161.60
	Canpotex(b)	923.6				439.7			1,239.80				1,298.90
	Canada	663.1				259.7			686.3				786.3
	India	331.9				315.8			475.2				1,579.70
	Australia	194.7				31.2			177.5				290.1
	China	191.1				86.9			173.3				160.4
	Argentina	167.3				163.1			258.3				266.7
	Colombia	145				55.2			143.5				155.9
	Japan	131.5				75.9			188.2				177.5
	Mexico	131.3				22.4			128.9				90.5
	Peru	101.8				35.6			56.9				95.1
	Chile	44.6				76.9			116.5				121.1
	Thailand	40.8				28.7			88.9				94
Other	223.7				72.4			271.7				209.3
Total international countries	5,211.80				2,913.30			6,074.30				7,487.10
United States	3,844.00				1,852.60			3,899.80				3,620.70
Consolidated	$	9,055.80			$	4,765.90		$	9,974.10			$	11,107.80
______________________________
(a)	Revenues are attributed to countries based on location of customer.
(b)	The export association of the Saskatchewan potash producers.
		December 31,
(in millions)		2014				2013
Long-lived assets:
Canada		$	4,993.00			$	5,372.30
Brazil		257.6				122.2
Other		22.5				51
Total international countries		5,273.10				5,545.50
United States		5,444.80				3,956.10
Consolidated		$	10,717.90			$	9,501.60
Excluded from the table above as of December 31, 2014 and 2013, are goodwill of $1,806.5 million and 1,794.4 million and deferred income taxes of $394.4 million and 152.2 million, respectively.
Net sales by product type for calendar 2014, seven months ended December 31, 2013, and fiscal 2013 and 2012 are as follows:
	Year Ended				Seven Months Ended December 31,			Years Ended May 31,
	December 31,
(in millions)	2014				2013			2013				2012
Sales by product type:
Phosphate Crop Nutrients	$	4,096.20			$	2,059.30		$	4,106.10			$	5,418.40
Potash Crop Nutrients	2,828.80				1,312.30			3,434.50				3,174.40
Crop Nutrient Blends	1,292.90				863.7			1,472.30				1,517.10
Other(a)	837.9				530.6			961.2				997.9
	$	9,055.80			$	4,765.90		$	9,974.10			$	11,107.80
______________________________
(a)	Includes sales for animal feed ingredients and industrial potash.

Schedule_II_Valuation_and_Qual

Schedule II Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2014
Valuation and Qualifying Accounts [Abstract]
Schedule II - Valuation And Qualifying Accounts	SCHEDULE II. VALUATION AND QUALIFYING ACCOUNTS
	For the year ended December 31, 2014, the seven months ended December 31, 2013 and the years ended May 31, 2013 and 2012
	In millions
	Column A	Column B		Column C						Column D			Column E
				Additions
	Description	Balance		Charges or			Charges or			Deductions			Balance at
		Beginning		(Reductions)			(Reductions)						End of Period(c)
		of Period		to Costs and			to Other
				Expenses			Accounts(a)(b)
	Allowance for doubtful accounts, deducted from accounts receivable in the balance sheet:
	Year ended May 31, 2012	$	23.6	$	—		$	(5.1	)	$	(0.1	)	$	18.4
	Year ended May 31, 2013	18.4		(1.0		)	(1.3		)	(0.1		)	16
	Seven months ended December 31, 2013	16		(0.9		)	(3.0		)	(1.7		)	10.4
	Year ended December 31, 2014	10.4		1.7			1.8			(1.8		)	12.1
	Income tax valuation allowance, related to deferred income taxes
	Year ended May 31, 2012	$	209.2	$	6.2		$	(35.2	)	$	—		$	180.2
	Year ended May 31, 2013	180.2		(77.7		)	(8.9		)	—			93.6
	Seven months ended December 31, 2013	93.6		48.1			(12.5		)	—			129.2
	Year ended December 31, 2014	129.2		(73.1		)	(27.8		)	—			28.3
	______________________________
	(a)	The income tax valuation allowance adjustment was recorded to accumulated other comprehensive income and deferred taxes.
	(b)	For the year ended December 31, 2014, $29.6 million of the income tax valuation allowance reductions related to the disposition of Argentina.
	(c)	Allowance for doubtful accounts balance includes $9.5 million, $8.5 million, $11.3 million and $13.5 million of allowance on long-term receivables recorded in other long term assets for the year ended December 31, 2014, the seven months ended December 31, 2013 and the fiscal years ended May 31, 2013 and 2012, respectively.

Significant_Accounting_Policie

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Statement of Presentation and Basis of Consolidation	Statement Presentation and Basis of Consolidation
	The accompanying Consolidated Financial Statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”). Throughout the Notes to Consolidated Financial Statements, amounts in tables are in millions of dollars except for per share data and as otherwise designated. As previously reported, in 2013 we changed our fiscal year end to December 31 from May 31. We are presenting our results of operations for the twelve months ended December 31, 2014, the seven-month transition period of June 1, 2013 through December 31, 2013 (the “Stub Period”) and the fiscal years ended May 31, 2013 and 2012.
	The accompanying Consolidated Financial Statements include the accounts of Mosaic and its majority owned subsidiaries, as well as the accounts of certain variable interest entities, including PhosChem, for which we were the primary beneficiary. Effective December 31, 2013, we and PhosChem’s other member each assumed responsibility for PhosChem’s former activities as they related to our respective products.  We subsequently dissolved PhosChem and continue to sell our own product internationally.  PhosChem had net sales of $492.0 million for the seven months ended December 31, 2013 and $1.3 billion and $2.4 billion for the years ended May 31, 2013 and 2012, respectively, which are included in our consolidated net sales and had minimal impact on our gross margin. Certain investments in companies where we do not have control but have the ability to exercise significant influence are accounted for by the equity method.
Accounting Estimates	Accounting Estimates
	Preparation of the Consolidated Financial Statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting periods. The more significant estimates made by management relate to the recoverability of non-current assets including goodwill, the useful lives and net realizable values of long-lived assets, environmental and reclamation liabilities including asset retirement obligations (“AROs”), the costs of our employee benefit obligations for pension plans and postretirement benefits, income tax related accounts including the valuation allowance against deferred income tax assets, inventory valuation and accruals for pending legal and environmental matters. Actual results could differ from these estimates.
Revenue Recognition	Revenue Recognition
	Revenue on North American sales is recognized when the product is delivered to the customer and/or when the risks and rewards of ownership are otherwise transferred to the customer and when the price is fixed or determinable. Revenue on North American export sales is recognized upon the transfer of title to the customer and when the other revenue recognition criteria have been met, which generally occurs when product enters international waters. Revenue from sales originating outside of North America is recognized upon transfer of title to the customer based on contractual terms of each arrangement and when the other revenue recognition criteria have been met. Our products are generally sold based on the market prices prevailing at the time the sales contract is signed or through contracts which are priced at the time of shipment based on a formula. In certain circumstances, the final price of our products is determined after shipment based on the current market at the time the price is agreed to with the customer. In such circumstances, revenue is recognized when the final price is fixed and the other revenue recognition criteria have been met. Shipping and handling costs are included as a component of cost of goods sold.
Non-Income Taxes	Non-Income Taxes
	We pay Canadian resource taxes consisting of the Potash Production Tax and resource surcharge. The Potash Production Tax is a Saskatchewan provincial tax on potash production and consists of a base payment and a profits tax. In addition to the Canadian resource taxes, royalties are payable to the mineral owners with respect to potash reserves or production of potash. These resource taxes and royalties are recorded in our cost of goods sold.
Foreign Currency Translation	Foreign Currency Translation
	The Company’s reporting currency is the U.S. dollar; however, for operations located in Canada and Brazil, the functional currency is the local currency. Assets and liabilities of these foreign operations are translated to U.S. dollars at exchange rates in effect at the balance sheet date, while income statement accounts and cash flows are translated to U.S. dollars at the average exchange rates for the period. For these operations, translation gains and losses are recorded as a component of accumulated other comprehensive income in equity until the foreign entity is sold or liquidated. Transaction gains and losses result from transactions that are denominated in a currency other than the functional currency of the operation, primarily accounts receivable in our Canadian entities denominated in U.S. dollars, and accounts payable in Brazil denominated in U.S. dollars. These foreign currency transaction gains and losses are presented separately in the Consolidated Statement of Earnings.
Cash and Cash Equivalents	Cash and Cash Equivalents
	Cash and cash equivalents include short-term, highly liquid investments with original maturities of 90 days or less, and other highly liquid investments that are payable on demand such as money market accounts, certain certificates of deposit and repurchase agreements. The carrying amount of such cash equivalents approximates their fair value due to the short-term and highly liquid nature of these instruments.
Concentration of Credit Risk	Concentration of Credit Risk
	In the U.S., we sell our products to manufacturers, distributors and retailers primarily in the Midwest and Southeast. Internationally, our potash products are sold primarily through Canpotex, an export association. A concentration of credit risk arises from our sales and accounts receivable associated with the international sales of potash product through Canpotex. We consider our concentration risk related to the Canpotex receivable to be mitigated by their credit policy which requires the underlying receivables to be substantially insured or secured by letters of credit.
Inventories	Inventories
	Inventories of raw materials, work-in-process products, finished goods and operating materials and supplies are stated at the lower of cost or market. Costs for substantially all inventories are determined using the weighted average cost basis. To determine the cost of inventory, we allocate fixed expense to the costs of production based on the normal capacity, which refers to a range of production levels and is considered the production expected to be achieved over a number of periods or seasons under normal circumstances, taking into account the loss of capacity resulting from planned maintenance.
	Market value of our inventory is defined as forecasted selling prices less reasonably predictable selling costs (net realizable value). Significant management judgment is involved in estimating forecasted selling prices including various demand and supply variables. Examples of demand variables include grain and oilseed prices, stock-to-use ratios and changes in inventories in the crop nutrients distribution channels. Examples of supply variables include forecasted prices of raw materials, such as phosphate rock, sulfur, ammonia, and natural gas, estimated operating rates and industry crop nutrient inventory levels. Results could differ materially if actual selling prices differ materially from forecasted selling prices. Charges for lower of cost or market are recognized in our Consolidated Statements of Earnings in the period when there is evidence of a decline of market value below cost.
Property, Plant and Equipment and Recoverability of Long-Lived Assets	Property, Plant and Equipment and Recoverability of Long-Lived Assets
	Property, plant and equipment are stated at cost. Costs of significant assets include capitalized interest incurred during the construction and development period. Repairs and maintenance, including planned major maintenance and plan turnaround costs, are expensed when incurred.
	Depletion expenses for mining operations, including mineral reserves, are generally determined using the units-of-production method based on estimates of recoverable reserves. Depreciation is computed principally using the straight-line method over the following useful lives: machinery and equipment three to 25 years, and buildings and leasehold improvements three to 40 years.
	We estimate initial useful lives based on experience and current technology. These estimates may be extended through sustaining capital programs. Factors affecting the fair value of our assets or periods of expected use may also affect the estimated useful lives of our assets and these factors can change. Therefore, we periodically review the estimated remaining lives of our facilities and other significant assets and adjust our depreciation rates prospectively where appropriate.
	Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. The carrying amount of a long-lived asset group is not recoverable if it exceeds the sum of the undiscounted cash flows expected to result from the use and eventual disposition of the asset group. If it is determined that an impairment loss has occurred, the loss is measured as the amount by which the carrying amount of the long-lived asset group exceeds its fair value.
Leases	Leases
	Leases in which the risk of ownership is retained by the lessor are classified as operating leases. Leases which substantially transfer all of the benefits and risks inherent in ownership to the lessee are classified as capital leases. Assets acquired under capital leases are depreciated on the same basis as property, plant and equipment. Rental payments are expensed on a straight-line basis. Leasehold improvements are depreciated over the depreciable lives of the corresponding fixed assets or the related lease term, whichever is shorter.
Contingencies	Contingencies
	Accruals for environmental remediation efforts are recorded when costs are probable and can be reasonably estimated. In determining these accruals, we use the most current information available, including similar past experiences, available technology, consultant evaluations, regulations in effect, the timing of remediation and cost-sharing arrangements.
	We are involved from time to time in claims and legal actions incidental to our operations, both as plaintiff and defendant. We have established what we currently believe to be adequate accruals for pending legal matters. These accruals are established as part of an ongoing worldwide assessment of claims and legal actions that takes into consideration such items as advice of legal counsel, individual developments in court proceedings, changes in the law, changes in business focus, changes in the litigation environment, changes in opponent strategy and tactics, new developments as a result of ongoing discovery, and past experience in defending and settling similar claims. The litigation accruals at any time reflect updated assessments of the then-existing claims and legal actions. The final outcome or potential settlement of litigation matters could differ materially from the accruals which we have established. For significant individual cases, we accrue legal costs expected to be incurred.
Pension and Other Postretirement Benefits	Pension and Other Postretirement Benefits
	Mosaic offers a number of benefit plans that provide pension and other benefits to qualified employees. These plans include defined benefit pension plans, supplemental pension plans, defined contribution plans and other postretirement benefit plans.
	We accrue the funded status of our plans, which is representative of our obligations under employee benefit plans and the related costs, net of plan assets measured at fair value. The cost of pensions and other retirement benefits earned by employees is generally determined with the assistance of an actuary using the projected benefit method prorated on service and management’s best estimate of expected plan investment performance, salary escalation, retirement ages of employees and expected healthcare costs.
Earnings Per Share	We use the two-class method to compute basic and diluted EPS. Earnings for the period are allocated pro-rata between the common shareholders and the participating securities. Our only participating securities are related to the Share Repurchase Agreement. The numerator for basic and diluted EPS is net earnings for common stockholders. The denominator for basic EPS is the weighted-average number of shares outstanding during the period. The denominator for diluted EPS also includes the weighted average number of additional common shares that would have been outstanding if the dilutive potential common shares had been issued, unless the shares are anti-dilutive, and excludes shares subject to forward contracts.
Investments in non-consolidated companies	We have investments in various international and domestic entities and ventures. The equity method of accounting is applied to such investments when the ownership structure prevents us from exercising a controlling influence over operating and financial policies of the businesses but still allow us to have significant influence. Under this method, our equity in the net earnings or losses of the investments is reflected as equity in net earnings of non-consolidated companies on our Consolidated Statements of Earnings. The effects of material intercompany transactions with these equity method investments are eliminated, including the gross profit on sales to and purchases from our equity-method investments which is deferred until the time of sale to the final third party customer. The cash flow presentation of dividends received from equity method investees is determined by evaluation of the facts, circumstances and nature of the distribution.
Goodwill	Goodwill is carried at cost, not amortized, and represents the excess of the purchase price and related costs over the fair value assigned to the net identifiable assets of a business acquired. We test goodwill for impairment on a quantitative basis at the reporting unit level on an annual basis or upon the occurrence of events that may indicate possible impairment. The test resulted in no impairment in the periods presented.
Income Taxes	In preparing our Consolidated Financial Statements, we utilize the asset and liability approach in accounting for income taxes. We recognize income taxes in each of the jurisdictions in which we have a presence. For each jurisdiction, we estimate the actual amount of income taxes currently payable or receivable, as well as deferred income tax assets and liabilities attributable to temporary differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred income tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which these temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date.
Accounting for asset retirement obligations	We recognize AROs in the period in which we have an existing legal obligation associated with the retirement of a tangible long-lived asset, and the amount of the liability can be reasonably estimated. The ARO is recognized at fair value when the liability is incurred with a corresponding increase in the carrying amount of the related long lived asset. We depreciate the tangible asset over its estimated useful life. The liability is adjusted in subsequent periods through accretion expense which represents the increase in the present value of the liability due to the passage of time. Such depreciation and accretion expenses are included in cost of goods sold for operating facilities and other operating expense for indefinitely closed facilities.
Accounting for derivative and hedging activities	We periodically enter into derivatives to mitigate our exposure to foreign currency risks and the effects of changing commodity and freight prices. We record all derivatives on the Consolidated Balance Sheets at fair value. The fair value of these instruments is determined by using quoted market prices, third party comparables, or internal estimates. We net our derivative asset and liability positions when we have a master netting arrangement in place. Changes in the fair value of the foreign currency, commodity, and freight derivatives are immediately recognized in earnings because we do not apply hedge accounting treatment to these instruments
Fair value measurements	Following is a summary of the valuation techniques for assets and liabilities recorded in our Consolidated Balance Sheets at fair value on a recurring basis:
	The foreign currency derivative instruments that we currently use are forward contracts, zero-cost collars, and futures, which typically expire within one year. Valuations are based on exchange-quoted prices, which are classified as Level 1. Some of the valuations are adjusted by a forward yield curve or interest rates. In such cases, these derivative contracts are classified within Level 2.
	The commodity derivative instruments that we currently use are forward purchase contracts, swaps, and three-way collars. Quoted market prices from NYMEX and AECO are used to determine the fair value of these instruments. These market prices are adjusted by a forward yield curve and are classified within Level 2.
	For cash and cash equivalents, accounts receivable, accounts payable and short-term debt, the carrying amount approximates fair value because of the short-term maturity of those instruments. The fair value of long-term debt is estimated using quoted market prices for the publicly registered notes and debentures, classified as Level 1 and Level 2, respectively, within the fair value hierarchy, depending on the market liquidity of the debt.
Share-Based Payments	The fair value of each option award is estimated on the date of the grant using the Black-Scholes option valuation model. Stock options vest in equal annual installments in the first three years following the date of grant (graded vesting). Stock options are expensed on a straight-line basis over the required service period, based on the estimated fair value of the award on the date of grant, net of estimated forfeitures.
	The fair value of restricted stock units is equal to the market price of our stock at the date of grant. Restricted stock units generally cliff vest after three years of continuous service and are expensed on a straight-line basis over the required service period, based on the estimated grant date fair value, net of estimated forfeitures.
	The fair value of each performance unit is determined using a Monte Carlo simulation. This valuation methodology utilizes assumptions consistent with those of our other share-based awards and a range of ending stock prices; however, the expected term of the awards is three years, which impacts the assumptions used to calculate the fair value of performance units as shown in the table below. Performance units are considered equity-classified fixed awards measured at grant-date fair value and not subsequently re-measured. Performance units cliff vest after three years of continuous service. Performance units are expensed on a straight-line basis over the required service period, based on the estimated grant date fair value of the award net of estimate forfeitures.

Other_Financial_Statement_Data1

Other Financial Statement Data (Tables)	12 Months Ended
	Dec. 31, 2014
Balance Sheet Related Disclosures [Abstract]
Schedule of Other Assets and Other Liabilities	The following provides additional information concerning selected balance sheet accounts:
		December 31,
	(in millions)	2014			2013
	Receivables
	Trade	$	624.9		$	460.1
	Non-trade	132.1			84.9
		757			545
	Less allowance for doubtful accounts	2.6			1.9
		$	754.4		$	543.1
	Inventories
	Raw materials	$	114.6		$	34
	Work in process	505.1			433.6
	Finished goods	1,025.50			891.6
	Operating materials and supplies	73.1			73.7
		$	1,718.30		$	1,432.90
	Other current assets
	Final price deferred(a)	$	49.9		$	154.3
	Income and other taxes receivable	201.9			272.6
	Prepaid expenses	63.8			115.8
	Assets held for sale(b)	6			111.9
	Other	46.6			52.2
		$	368.2		$	706.8
		December 31,
	(in millions)	2014			2013
	Accrued liabilities
	Non-income taxes	$	29.9		$	23.6
	Payroll and employee benefits	172.8			111.8
	Asset retirement obligations	87.9			86.3
	Customer prepayments	101.6			131.9
	Other	333.9			312.7
		$	726.1		$	666.3
	Other noncurrent liabilities
	Asset retirement obligations	$	771.6		$	637.6
	Accrued pension and postretirement benefits	77.6			69
	Unrecognized tax benefits	89.2			96.3
	Other	261.6			124.2
		$	1,200.00		$	927.1
	______________________________
	(a)	Final price deferred is product that has shipped to customers, but the price has not yet been agreed upon. This has not been included in inventory as it is not held for sale.
	(b)	See further description of assets held for sale in Footnote 22.
Schedule of Other Nonoperating Income (Expense)	Interest expense, net was comprised of the following in the calendar year 2014, seven months ended December 31, 2013, and fiscal 2013 and 2012:
		Year Ended			Seven Months Ended December 31,			Years Ended May 31,
		December 31,
	(in millions)	2014			2013			2013		2012
	Interest income	$	21.3		$	9.5		$	18.8	$	20.1
	Less interest expense	128.9			22.8			—		1.4
	Interest income (expense), net	$	(107.6	)	$	(13.3	)	$	18.8	$	18.7

Property_Plant_and_Equipment_T

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Property Plant And Equipment	Property, plant and equipment consist of the following:
		December 31,
	(in millions)	2014		2013
	Land	$	233.7	$	188.6
	Mineral properties and rights	3,515.50		2,932.60
	Buildings and leasehold improvements	2,242.00		1,969.50
	Machinery and equipment	6,660.60		5,994.10
	Construction in-progress	1,295.50		1,516.80
		13,947.30		12,601.60
	Less: accumulated depreciation and depletion	4,633.40		4,025.00
		$	9,313.90	$	8,576.60

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Schedule of earnings per share	The following is a reconciliation of the numerator and denominator for the basic and diluted EPS computations:
		Year Ended			Seven Months Ended			Years Ended May 31,
		December 31,			December 31,
	(in millions)	2014			2013			2013		2012
	Net earnings attributed to Mosaic	$	1,028.60		$	340		$	1,888.70	$	1,930.20
	Undistributed earnings attributable to participating securities	(22.3		)	(4.0		)	—		—
	Numerator for basic and diluted earnings available to common stockholders	$	1,006.30		$	336		$	1,888.70	$	1,930.20
	Basic weighted average number of shares outstanding	382.4			425.9			425.7		435.2
	Shares subject to forward contract	(8.3		)	(5.1		)	—		—
	Basic weighted average number of shares outstanding attributable to common stockholders	374.1			420.8			425.7		435.2
	Dilutive impact of share-based awards	1.5			1.2			1.2		1.3
	Diluted weighted average number of shares outstanding	375.6			422			426.9		436.5
	Basic net earnings per share	$	2.69		$	0.8		$	4.44	$	4.44
	Diluted net earnings per share	$	2.68		$	0.8		$	4.42	$	4.42

Cash_Flow_Information_Tables

Cash Flow Information (Tables)	12 Months Ended
	Dec. 31, 2014
Supplemental Cash Flow Elements [Abstract]
Schedule Of Cash Flow Supplemental Disclosures Table	Supplemental disclosures of cash paid for interest and income taxes and non-cash investing and financing information is as follows:
		Year Ended		Seven Months Ended		Years Ended May 31,
		December 31,		December 31,
	(in millions)	2014		2013		2013		2012
	Cash paid during the period for:
	Interest	$	155.9	$	28.7	$	52	$	76.7
	Less amount capitalized	34		25		52		55.7
	Cash interest, net	$	121.9	$	3.7	$	—	$	21
	Income taxes	$	113.2	$	155.7	$	299.9	$	516.4

Recovered_Sheet1

Investments in Non-Consolidated Companies (Tables)	12 Months Ended
	Dec. 31, 2014
Equity Method Investments and Joint Ventures [Abstract]
Schedule of Equity Method Investments	A summary of our equity-method investments, which were in operation as of December 31, 2014, is as follows:
	Entity		Economic Interest
	Gulf Sulphur Services LTD., LLLP		50	%
	River Bend Ag, LLC		50	%
	IFC S.A.		45	%
	Yunnan Three Circles Sinochem Cargill Fertilizers Co. Ltd.		35	%
	Miski Mayo Mine		35	%
	Wa’ad Al Shamal Joint Venture		25	%
	Canpotex		38.8	%
	The summarized financial information shown below includes all non-consolidated companies carried on the equity method.
		Year Ended			Seven Months Ended December 31,		Years Ended May 31,
		December 31,
	(in millions)	2014			2013		2013		2012
	Net sales	$	3,814.10		$	1,846.50	$	4,475.20	$	4,938.40
	Net earnings	20			12.1		67.5		97.9
	Mosaic’s share of equity in net earnings (loss)	(2.2		)	10.9		18.3		13.3
	Total assets	4,344.90			1,658.50		1,841.40		1,776.00
	Total liabilities	3,107.00			985.3		1,149.80		1,005.00
	Mosaic’s share of equity in net assets	394			250.9		256.4		282.8

Goodwill_Tables

Goodwill (Tables)	12 Months Ended
	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	The changes in the carrying amount of goodwill, by reporting unit, as of December 31, 2014 and 2013, are as follows:
	(in millions)	Phosphates		Potash		Total
	Balance as of May 31, 2013	546.6		1,298.00		1,844.60
	Foreign currency translation	—		(39.4	)	(39.4	)
	Reallocation of goodwill to assets held for sale	(10.8	)	—		(10.8	)
	Balance at December 31, 2013	535.8		1,258.60		1,794.40
	Foreign currency translation	1.6		(95.7	)	(94.1	)
	Goodwill acquired in ADM acquisition	105.9		—		105.9
	Reallocation of goodwill to assets held for sale	5.1		(4.8	)	0.3
	Balance as of December 31, 2014	648.4		1,158.10		1,806.50

Financing_Arrangements_Tables

Financing Arrangements (Tables)	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Schedule of long-term debt, including current maturites	Long-term debt as of December 31, 2014 and 2013, respectively, consisted of the following:
	(in millions)		December 31,	December 31,	Maturity Date	December 31,		Combination Fair		Discount on Notes Issuance			December 31,		December 31,		Combination Fair		Discount on Notes Issuance			December 31,
			2014	2014		2014		Market					2014		2013		Market					2013
			Stated	Effective		Stated		Value Adjustment					Carrying		Stated		Value Adjustment					Carrying
			Interest	Interest		Value							Value		Value							Value
			Rate	Rate
	Industrial revenue and recovery zone bonds		1.15%	1.15%	2040	$	15.9	$	—	$	—		$	15.9	$	16.8	$	—	$	—		$	16.8
	Unsecured notes		3.75% -	4.73%	2021-	2,750.00		—		(10.1		)	2,739.90		2,750.00		—		(11.2		)	2,738.80
			5.63%		2043
	Unsecured debentures		7.30% -	7.08%	2018-	236.1		2.8		—			238.9		236.1		3.1		—			239.2
			7.38%		2028
	Term Loans		Libor plus 1.125%	1.28%	2017-	800		—		—			800		—		—		—			—
					2019
	Other		2.50% -	6.59%	2014-	24.3		—		—			24.3		14.5		—		—			14.5
			9.00%		2023
	Total long-term debt					3,826.30		2.8		(10.1		)	3,819.00		3,017.40		3.1		(11.2		)	3,009.30
	Less current portion					41.6		0.4		(1.0		)	41		1.1		0.4		(1.1		)	0.4
	Total long-term debt, less current maturities					$	3,784.70	$	2.4	$	(9.1	)	$	3,778.00	$	3,016.30	$	2.7	$	(10.1	)	$	3,008.90
Scheduled maturities of long-term debt	Scheduled maturities of long-term debt are as follows for the periods ending December 31:
	(in millions)
	2015	$	41
	2016	43.7
	2017	365.9
	2018	132.4
	2019	315.7
	Thereafter	2,920.30
	Total	$	3,819.00

Income_Taxes_Table

Income Taxes (Table)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Provision For Income Taxes	The provision for income taxes for calendar 2014, the seven months ended December 31, 2013, and the fiscal years ended May 31, 2013 and 2012 consisted of the following:
		Year Ended			Seven Months Ended December 31,			Years Ended May 31,
		December 31,
	(in millions)	2014			2013			2013			2012
	Current:
	Federal	$	46		$	(25.0	)	$	138.8		$	314.5
	State	11.8			(15.1		)	42.5			61
	Non-U.S.	265.4			141.9			81.5			77
	Total current	323.2			101.8			262.8			452.5
	Deferred:
	Federal	(103.6		)	32.8			(32.9		)	7.4
	State	(16.4		)	(0.3		)	(14.1		)	9
	Non-U.S.	(18.5		)	18.3			125.2			242.5
	Total deferred	(138.5		)	50.8			78.2			258.9
	Provision for income taxes	$	184.7		$	152.6		$	341		$	711.4
Schedule Of Effective Income Tax Rate	The components of earnings from consolidated companies before income taxes, and the effects of significant adjustments to tax computed at the federal statutory rate, were as follows:
		Year Ended			Seven Months Ended December 31,			Years Ended May 31,
		December 31,
	(in millions)	2014			2013			2013			2012
	United States earnings	$	312.9		$	208.2		$	1,158.10		$	1,412.70
	Non-U.S. earnings	904.4			276			1,056.40			1,216.20
	Earnings from consolidated companies before income taxes	$	1,217.30		$	484.2		$	2,214.50		$	2,628.90
	Computed tax at the U.S. federal statutory rate of 35%	35		%	35		%	35		%	35		%
	State and local income taxes, net of federal income tax benefit	0.1		%	1.2		%	1.6		%	1.6		%
	Percentage depletion in excess of basis	(9.7		)%	(15.7		)%	(7.1		)%	(6.6		)%
	Impact of non-U.S. earnings	(3.8		)%	3.8		%	(10.2		)%	(2.9		)%
	Non-taxable change in value of share repurchase agreement	1.7		%	(5.3		)%	—		%	—		%
	Change in valuation allowance	(7.6		)%	10		%	(3.6		)%	0.4		%
	Other items (none in excess of 5% of computed tax)	(0.5		)%	2.5		%	(0.3		)%	(0.4		)%
	Effective tax rate	15.2		%	31.5		%	15.4		%	27.1		%
Schedule Of Deferred Tax Assets And Liabilities	Significant components of our deferred tax liabilities and assets as of December 31 were as follows:
		December 31,
	(in millions)	2014			2013
	Deferred tax liabilities:
	Depreciation and amortization	$	897.9		$	1,029.80
	Depletion	397.9			388.6
	Partnership tax basis differences	120.1			106.2
	Undistributed earnings of non-U.S. subsidiaries	219.5			319.6
	Other liabilities	41.5			150.9
	Total deferred tax liabilities	$	1,676.90		$	1,995.10
	Deferred tax assets:
	Alternative minimum tax credit carryforwards	$	144.5		$	113.8
	Capital loss carryforwards	—			54.6
	Foreign tax credit carryforwards	450.5			580.9
	Net operating loss carryforwards	103.1			145.3
	Pension plans and other benefits	29.1			17.1
	Asset retirement obligations	263.7			260
	Other assets	269.7			182.7
	Subtotal	1,260.60			1,354.40
	Valuation allowance	28.3			129.2
	Net deferred tax assets	1,232.30			1,225.20
	Net deferred tax liabilities	$	(444.6	)	$	(769.9	)
Summary Of Income Tax Uncertainties
		Year Ended December 31,			Seven Months Ended December 31,			Year ended May 31,
	(in millions)	2014			2013			2013
	Gross unrecognized tax benefits, beginning of period	$	99.2		$	316.8		$	476.9
	Gross increases:
	Prior period tax positions	33			128.5			7.7
	Current period tax positions	2.8			0.4			36.6
	Gross decreases:
	Prior period tax positions	—			(24.0		)	(204.3		)
	Settlements	(32.6		)	(323.7		)	—
	Currency translation	(1.8		)	1.2			(0.1		)
	Gross unrecognized tax benefits, end of period	$	100.6		$	99.2		$	316.8

Accounting_for_Asset_Retiremen1

Accounting for Asset Retirement Obligations (Tables)	12 Months Ended
	Dec. 31, 2014
Asset Retirement Obligation Disclosure [Abstract]
Schedule of Asset Retirement Obligations	A reconciliation of our AROs is as follows:
		Year Ended December 31,			Seven Months Ended December 31,
	(in millions)	2014			2013
	AROs, beginning of period	$	723.9		$	658.5
	Liabilities acquired in CF Phosphate Assets Acquisition	145.6			—
	Liabilities incurred	21.7			13.6
	Liabilities settled	(91.1		)	(37.0		)
	Accretion expense	42.1			21.6
	Revisions in estimated cash flows	17.3			67.2
	AROs, end of period	859.5			723.9
	Less current portion	87.9			86.3
		$	771.6		$	637.6

Accounting_for_Derivative_Inst1

Accounting for Derivative Instruments and Hedging Activities (Tables)	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule Of Derivative Instruments Notional Amounts	The following is the total absolute notional volume associated with our outstanding derivative instruments:
	(in millions of Units)
	Instrument	Derivative Category	Unit of Measure	December 31,	December 31,
				2014	2013
	Foreign currency derivatives	Foreign Currency	US Dollars	1,132.30	940.2
	Natural gas derivatives	Commodity	MMbtu	24.4	8.2

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The carrying amounts and estimated fair values of our financial instruments are as follows:
		December 31,
		2014				2013
		Carrying		Fair		Carrying		Fair
	(in millions)	Amount		Value		Amount		Value
	Cash and cash equivalents	$	2,374.60	$	2,374.60	$	5,293.10	$	5,293.10
	Accounts receivable	754.4		754.4		543.1		543.1
	Accounts payable trade	797.3		797.3		570.2		570.2
	Short-term debt	13.5		13.5		22.6		22.6
	Long-term debt, including current portion	3,819.00		4,101.20		3,009.30		3,059.60

Pension_Plans_and_Other_Benefi1

Pension Plans and Other Benefits (Tables)	12 Months Ended
	Dec. 31, 2014
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Schedule Of Defined Benefit Plans Disclosures	The year-end status of the North American pension plans was as follows:
		Pension Plans
		Year Ended December 31,				Seven Months
						Ended
						December 31,
	(in millions)	2014				2013
	Change in projected benefit obligation:
	Benefit obligation at beginning of period	$	728			$	788.6
	Service cost	6.3				4.6
	Interest cost	32.8				19
	Actuarial (gain) loss	124.8				(49.3		)
	Currency fluctuations	(26.8		)		(11.8		)
	Benefits paid	(42.1		)		(23.1		)
	Special termination costs	5.4				—
	Projected benefit obligation at end of period	$	828.4			$	728
	Change in plan assets:
	Fair value at beginning of period	$	736.9			$	707.6
	Currency fluctuations	(26.3		)		(9.1		)
	Actual return	110.7				18.8
	Company contribution	32.9				42.7
	Benefits paid	(42.1		)		(23.1		)
	Fair value at end of period	$	812.1			$	736.9
	Funded/(unfunded) status of the plans as of the end of period	$	(16.3	)		$	8.9
	Amounts recognized in the consolidated balance sheets:
	Noncurrent assets	$	10.1			$	30.2
	Current liabilities	(0.6		)		(0.6		)
	Noncurrent liabilities	(25.8		)		(20.7		)
	Amounts recognized in accumulated other comprehensive (income) loss
	Prior service costs (credits)	$	18.7			$	24.9
	Actuarial (gain) loss	120.6				73.1
Schedule Of Net Benefit Costs	The components of net annual periodic benefit costs and other amounts recognized in other comprehensive income include the following components:
			Pension Plans
	(in millions)		Year Ended				Seven Months Ended December 31,				Years Ended May 31,
			December 31,
	Net Periodic Benefit Cost		2014				2013				2013				2012
	Service cost		$	6.3			$	4.6			$	6.5			$	5.6
	Interest cost		32.8				19				32.6				34.5
	Expected return on plan assets		(44.0		)		(25.1		)		(37.3		)		(35.8		)
	Amortization of:
	Prior service cost/(credit)		1.9				1.4				1.3				1.3
	Actuarial (gain)/loss		4.7				5.4				16.1				13.4
	Preliminary net periodic benefit cost		$	1.7			$	5.3			$	19.2			$	19
	Curtailment expense		2.3				—				—				—
	Special termination costs		5.4				—				—				—
	Total net periodic benefit cost		$	9.4			$	5.3			$	19.2			$	19
	Other Changes in Plan Assets and Benefit
	Obligations Recognized in Other
	Comprehensive Income
	Prior service cost (credit) recognized in other comprehensive income		$	(1.9	)		$	(1.3	)		$	14.1			$	(1.3	)
	Net actuarial loss (gain) recognized in other comprehensive income		53.3				(48.5		)		(5.9		)		36.3
	Total recognized in other comprehensive income		$	51.4			$	(49.8	)		$	8.2			$	35
	Total recognized in net periodic benefit (income) cost and other comprehensive income		$	60.8			$	(44.5	)		$	27.4			$	54
Schedule Of Expected Benefit Payments	The following estimated benefit payments, which reflect estimated future service are expected to be paid by the related plans in the calendar years ending December 31:
	(in millions)	Pension Plans			Other Postretirement			Medicare Part D
		Benefit Payments			Plans Benefit Payments			Adjustments
	2015	42.2			5.8			0.6
	2016	43.4			5.8			0.6
	2017	44.3			5.5			0.6
	2018	45.9			5.1			0.6
	2019	47.3			4.5			0.6
	2020-2024	247.8			16.9			1.9
Schedule of Allocation of Plan Assets	The following tables provide fair value measurement, by asset class of the Company’s defined benefit plan assets for both the U.S. and Canadian plans:
	(in millions)	December 31, 2014
	Pension Plan Assets	Total				Level 1				Level 2				Level 3
	Asset Category
	Cash	$	8.6			$	8.6			$	—			$	—
	Equity securities(a)	302.2				—				285.9				16.3
	Fixed income(b)	491.9				—				491.9				—
	Private equity funds	9.4				—				—				9.4
	Total assets at fair value	$	812.1			$	8.6			$	777.8			$	25.7
	(in millions)	December 31, 2013
	Pension Plan Assets	Total				Level 1				Level 2				Level 3
	Asset Category
	Cash	$	9.8			$	9.8			$	—			$	—
	Equity securities(a)	281.1				—				262.8				18.3
	Fixed income(b)	433.9				—				433.9				—
	Private equity funds	12.1				—				—				12.1
	Total assets at fair value	$	736.9			$	9.8			$	696.7			$	30.4
	______________________________
	(a)	This class includes several funds that are invested approximately 46% in U.S. equity securities, 26% in international equity securities, 23% in Canadian equity securities, and 5% in other real estate securities.
	(b)	This class includes several funds that are invested approximately 57% in corporate debt securities, 22% in other governmental securities in the U.S. and Canada, 13% in U.S. government debt securities, 5% in foreign entity debt securities and 3% in Canadian government securities.
Schedule of Assumptions Used	Weighted average assumptions used to determine benefit obligations were as follows:
		Pension Plans
		Year Ended			Seven Months Ended December 31,			Years Ended May 31,
		December 31,
		2014			2013			2013			2012
	Discount rate	3.95	%		4.75	%		4.25	%		4.44	%
	Expected return on plan assets	6.15	%		6.15	%		6.13	%		6.29	%
	Rate of compensation increase	3.5	%		3.5	%		4	%		4	%
	Weighted-average assumptions used to determine net benefit cost were as follows:
		Pension Plans
		Year Ended			Seven Months Ended December 31,			Years Ended May 31,
		December 31,
		2014			2013			2013			2012
	Discount rate	4.75	%		4.25	%		4.44	%		5.13	%
	Expected return on plan assets	6.15	%		6.13	%		6.29	%		6.87	%
	Rate of compensation increase	3.5	%		4	%		4	%		4	%

Sharebased_Payments_Tables

Share-based Payments (Tables)	12 Months Ended
	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Share-based Compensation, Stock Options, Activity	A summary of the status of our stock options as of December 31, 2014, and activity during the calendar year 2014, is as follows:
		Shares		Weighted			Weighted Average Remaining Contractual Term (Years)	Aggregate
		(in millions)		Average				Intrinsic
				Exercise				Value
				Price
	Outstanding as of December 31, 2013	2.6		$	44.82		5	$	28
	Granted	0.2		$	49.73
	Exercised	(0.4	)	$	18.91
	Outstanding as of December 31, 2014	2.4		$	48.88		4.8	$	16
	Exercisable as of December 31, 2014	2		$	48.16		4	$	16
Schedule of Share-based Compensation, Restricted Stock Units Award Activity	A summary of the status of our restricted stock units as of December 31, 2014, and activity during calendar 2014, is as follows:
		Shares		Weighted
		(in millions)		Average
				Grant
				Date Fair
				Value Per
				Share
	Restricted stock units as of December 31, 2013	0.8		$	57.5
	Granted	0.6		48.72
	Issued and cancelled	(0.4	)	55.51
	Restricted stock units as of December 31, 2014	1		$	53.12
Schedule of Nonvested Performance-based Units Activity	A summary of our performance unit activity during calendar 2014 is as follows:
		Shares		Weighted
		(in  millions)		Average
				Grant
				Date Fair
				Value Per
				Share
	Outstanding as of December 31, 2013	0.4		$	69.64
	Granted	0.1		61.11
	Outstanding as of December 31, 2014	0.5		$	64.31
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Disclosure of Share-based Compensation Arrangements by Share-based Payment Award
		Year Ended		Seven Months Ended December 31,		Years Ended May 31,
		December 31,
		2014		2013		2013		2012
	Weighted average assumptions used in option valuations:
	Expected volatility	42.4	%	43.87	%	47.7	%	51.8	%
	Expected dividend yield	2.01	%	1.85	%	1.74	%	0.28	%
	Expected term (in years)	7		7		7		5
	Risk-free interest rate	2.31	%	1.99	%	0.92	%	1.46	%
Performance Stock Unit [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Disclosure of Share-based Compensation Arrangements by Share-based Payment Award	A summary of the assumptions used to estimate the fair value of performance units is as follows:
		Year Ended		Seven Months Ended December 31,		Years Ended May 31,
		December 31,
		2014		2013		2013		2012
	Weighted average assumptions used in performance unit valuations:
	Expected volatility	30.39	%	32.78	%	38.05	%	54.72	%
	Expected dividend yield	2.08	%	1.85	%	1.74	%	0.28	%
	Expected term (in years)	3		3		3		3
	Risk-free interest rate	0.77	%	0.61	%	0.31	%	0.69	%

Commitments_Tables

Commitments (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Schedule of commitments and contingencies	A schedule of future minimum long-term purchase commitments, based on December 31, 2014 market prices, and minimum lease payments under non-cancelable operating leases as of December 31, 2014 follows:
	(in millions)	Purchase		Operating
		Commitments		Leases
	2015	$	2,420.60	$	58
	2016	532.4		50.1
	2017	422.1		43.9
	2018	364.9		34.5
	2019	366		29.1
	Subsequent years	4,189.40		90.6
		$	8,295.40	$	306.2

Related_Party_Transactions_Tab

Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2014
Related Party Transactions [Abstract]
Schedule of Related Party Transactions	The Consolidated Statements of Earnings included the following transactions with our non-consolidated companies:
		Year Ended		Seven Months Ended December 31,
		December 31,				Years Ended May 31,
	(in millions)	2014		2013		2013		2012
	Transactions with non-consolidated companies included in net sales	$	946	$	448.8	$	1,263.90	$	1,321.20
	Transactions with non-consolidated companies included in cost of goods sold	532.8		257.5		632		557.3

Acquisitions_Acquisitions_Tabl

Acquisitions Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2014
Business Acquisition [Line Items]
Schedule of Acquisitions, Pro Forma Information
		(in millions)	Years Ended
			December 31,
			2014		2013
		Net sales	$	9,947.70	$	10,820.90
		Net earnings attributable to Mosaic	$	1,014.60	$	1,079.80
CF Phosphate Assets Acquisition [Member]
Business Acquisition [Line Items]
Schedule of Acquisitions, Recognized Identified Assets Acquired and Liabilities Assumed	The following table summarizes the amounts of the assets acquired and liabilities assumed as recognized with the acquisition.
	(in millions)
	Inventory	$	144.1
	Other current assets	0.5
	Mineral properties and rights	499.7
	Property, plant and equipment	627.1
	Funds in trust for asset retirement obligations (1)	203.7
	Other assets	56.8
	Current liabilities	(1.5		)
	Other liabilities	(9.0		)
	Asset retirement obligation	(145.6		)
	Total purchase price paid	$	1,375.80
Brazil and Paraguay Distribution Business Acquisition [Member]
Business Acquisition [Line Items]
Schedule of Acquisitions, Recognized Identified Assets Acquired and Liabilities Assumed	The fair value of these assets and liabilities is provisional pending determination of the final valuation:
	(in millions)
	Inventory	$	122.5
	Other current assets	10.3
	Property, plant and equipment	95.1
	Goodwill	105.9
	Other assets	18.6
	Accounts payable	(19.2		)
	Other current liabilities	(24.2		)
	Estimated value of acquisition	$	309
	Estimated post closing working capital adjustment	$	40.6
	Initial payment for acquisition	$	349.6

Business_Segments_Tables

Business Segments (Tables)	12 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
Schedule of segment reporting by segment	Segment information for calendar 2014, the seven months ended December 31, 2013, and fiscal 2013 and 2012 is as follows:
	(in millions)		Phosphates				Potash			Corporate,				Total
										Eliminations
										and Other
	Year Ended December 31, 2014
	Net sales to external customers		$	6,194.00			$	2,839.90		$	21.9			$	9,055.80
	Intersegment net sales		—				11.7			(11.7		)		—
	Net sales		6,194.00				2,851.60			10.2				9,055.80
	Gross margin		1,071.20				897.7			(42.3		)		1,926.60
	Carlsbad restructuring expense		—				125.4			—				125.4
	Operating earnings (loss)		766.7				630.6			(85.5		)		1,311.80
	Capital expenditures		439				470.7			19.4				929.1
	Depreciation, depletion and amortization expense		368.9				355.1			26.9				750.9
	Equity in net earnings (loss) of nonconsolidated companies		(4.6		)		—			2.4				(2.2		)
	Seven Months Ended December 31, 2013
	Net sales to external customers		$	3,438.20			$	1,323.90		$	3.8			$	4,765.90
	Intersegment net sales		—				63.3			(63.3		)		—
	Net sales		3,438.20				1,387.20			(59.5		)		4,765.90
	Gross margin		445				374.3			9				828.3
	Operating earnings (loss)		199.7				224.6			(7.4		)		416.9
	Capital expenditures		298.7				471			30.3				800
	Depreciation, depletion and amortization expense		177.2				197.2			11.8				386.2
	Equity in net earnings of nonconsolidated companies		10.1				—			0.8				10.9
	Year Ended May 31, 2013
	Net sales to external customers		$	6,494.60			$	3,469.10		$	10.4			$	9,974.10
	Intersegment net sales		—				60.2			(60.2		)		—
	Net sales		6,494.60				3,529.30			(49.8		)		9,974.10
	Gross margin		1,162.20				1,611.30			(13.3		)		2,760.20
	Operating earnings (loss)		848.1				1,393.00			(31.5		)		2,209.60
	Capital expenditures		427.5				1,017.70			143.1				1,588.30
	Depreciation, depletion and amortization expense		287.3				301.9			15.6				604.8
	Equity in net earnings of nonconsolidated companies		16.4				—			1.9				18.3
	Year Ended May 31, 2012
	Net sales to external customers		$	7,839.20			$	3,263.10		$	5.5			$	11,107.80
	Intersegment net sales		—				38.2			(38.2		)		—
	Net sales		7,839.20				3,301.30			(32.7		)		11,107.80
	Gross margin		1,466.90				1,622.00			(3.9		)		3,085.00
	Operating earnings (loss)		1,179.10				1,457.30			(25.3		)		2,611.10
	Capital expenditures		407.9				1,171.40			60				1,639.30
	Depreciation, depletion and amortization expense		263.9				233.1			11.1				508.1
	Equity in net earnings of nonconsolidated companies		11.9				—			1.4				13.3
	Total assets as of December 31, 2014		$	11,392.20			$	8,296.60		$	(1,405.8	)		$	18,283.00
	Total assets as of December 31, 2013		9,945.10				9,597.40			11.5				19,554.00
Financial Information Relating to Our Operations by Geographic Area	Financial information relating to our operations by geographic area is as follows:
		Year Ended				Seven Months Ended December 31,			Years Ended May 31,
		December 31,
	(in millions)	2014				2013			2013				2012
	Net sales(a):
	Brazil	$	1,921.40			$	1,249.80		$	2,069.30			$	2,161.60
	Canpotex(b)	923.6				439.7			1,239.80				1,298.90
	Canada	663.1				259.7			686.3				786.3
	India	331.9				315.8			475.2				1,579.70
	Australia	194.7				31.2			177.5				290.1
	China	191.1				86.9			173.3				160.4
	Argentina	167.3				163.1			258.3				266.7
	Colombia	145				55.2			143.5				155.9
	Japan	131.5				75.9			188.2				177.5
	Mexico	131.3				22.4			128.9				90.5
	Peru	101.8				35.6			56.9				95.1
	Chile	44.6				76.9			116.5				121.1
	Thailand	40.8				28.7			88.9				94
	Other	223.7				72.4			271.7				209.3
	Total international countries	5,211.80				2,913.30			6,074.30				7,487.10
	United States	3,844.00				1,852.60			3,899.80				3,620.70
	Consolidated	$	9,055.80			$	4,765.90		$	9,974.10			$	11,107.80
	______________________________
	(a)	Revenues are attributed to countries based on location of customer.
	(b)	The export association of the Saskatchewan potash producers.
			December 31,
	(in millions)		2014				2013
	Long-lived assets:
	Canada		$	4,993.00			$	5,372.30
	Brazil		257.6				122.2
	Other		22.5				51
	Total international countries		5,273.10				5,545.50
	United States		5,444.80				3,956.10
	Consolidated		$	10,717.90			$	9,501.60
Net Sales by Product Type	Net sales by product type for calendar 2014, seven months ended December 31, 2013, and fiscal 2013 and 2012 are as follows:
		Year Ended				Seven Months Ended December 31,			Years Ended May 31,
		December 31,
	(in millions)	2014				2013			2013				2012
	Sales by product type:
	Phosphate Crop Nutrients	$	4,096.20			$	2,059.30		$	4,106.10			$	5,418.40
	Potash Crop Nutrients	2,828.80				1,312.30			3,434.50				3,174.40
	Crop Nutrient Blends	1,292.90				863.7			1,472.30				1,517.10
	Other(a)	837.9				530.6			961.2				997.9
		$	9,055.80			$	4,765.90		$	9,974.10			$	11,107.80
	______________________________
	(a)	Includes sales for animal feed ingredients and industrial potash.

Organization_and_Nature_of_Bus1

Organization and Nature of Business (Details)	12 Months Ended
	Dec. 31, 2014
Miski Mayo Joint Venture [Member]
Schedule of Equity Method Investments [Line Items]
Mosaic's ownership percentage	35.00%
Wa'ad Al Shamal Joint Venture [Member]
Schedule of Equity Method Investments [Line Items]
Mosaic's ownership percentage	25.00%
Percentage of joint venture production Mosaic expects to market	25.00%

Cargill_Transaction_Details

Cargill Transaction (Details) (USD $)	0 Months Ended
	25-May-11	Oct. 06, 2011	Nov. 26, 2013	Nov. 26, 2014	Sep. 29, 2011	Dec. 31, 2014	Dec. 31, 2013
Equity [Abstract]
Former percentage ownership by Cargill and certain of its subsidiaries	64.00%
Shares Received By Exchanging Cargill Stockholders	178,300,000
Percentage Of Outstanding Shares Held By Cargill After Split Off	40.00%
Percentage of Cargill voting power after split off	82.00%
Mosaic shares received by Cargill debt holders	107,500,000
Shares sold in secondary offer	115,000,000
Remaining shares of Mosaic stock received by Cargill stockholders and not sold in the formation offering	128,800,000
Exchanging Cargill Stockholders [Member]
Conversion of Stock [Line Items]
Number of shares remaining to be converted						17,176,046
Common Class A [Member]
Conversion of Stock [Line Items]
Common stock, par value (in usd per share)						0.01	$0.01
Common Class B [Member]
Conversion of Stock [Line Items]
Number of shares converted		113,000,000
Common stock, par value (in usd per share)						0.01	$0.01
Common Class A, Series A-1 [Member]
Conversion of Stock [Line Items]
Number of shares converted			42,900,000
Common Class A, Series A-1 [Member] | MAC Trusts [Member]
Conversion of Stock [Line Items]
Number of shares converted			21,647,007
Common Class A, Series A-2 [Member] | Exchanging Cargill Stockholders [Member]
Conversion of Stock [Line Items]
Number of shares converted				17,176,068
Common Class A, Series A-4 [Member] | MAC Trusts [Member]
Conversion of Stock [Line Items]
Number of shares converted					20,700,000
No Class Common Stock [Member]
Conversion of Stock [Line Items]
Common stock, par value (in usd per share)			0.01			0.01	$0.01
Cargill [Member]
Conversion of Stock [Line Items]
Prohibited ownership percentage to benefit from facilitation to acquire our stock from Cargill transaction	10.00%
Prohibited ownership percentage by management to benefit from facilitation to acquire our stock from Cargill transaction	5.00%

Share_Repurchases_Details

Share Repurchases (Details) (USD $)	0 Months Ended	7 Months Ended	12 Months Ended
	Nov. 17, 2011	Dec. 31, 2013	Dec. 31, 2014	31-May-13	31-May-12	Feb. 28, 2014
Share repurchase [Line Items]
Payments for Repurchase of Common Stock		$0	$2,755,300,000	$0	$1,162,500,000
Shares designated to be sold during 15 months after the split-off	157,000,000
Maximum number of months to complete disposition of stock	15 months
Authorized amount under our share repurchase program						1,000,000,000
Repurchase Program [Member]
Share repurchase [Line Items]
Payments for Repurchase of Common Stock			727,300,000
Common Class A [Member]
Share repurchase [Line Items]
Number of trading days to calculate weighted average stock price			20 days
Common Class A [Member] | Repurchase Program [Member]
Share repurchase [Line Items]
Repurchase of common stock (in shares)			8,193,698
Common Class A [Member] | MAC Trusts Share Repurchase Agreement [Member]
Share repurchase [Line Items]
Payments for Repurchase of Common Stock			2,000,000,000
No Class Common Stock [Member] | Repurchase Program [Member]
Share repurchase [Line Items]
Repurchase of common stock (in shares)			7,585,085
Common Class A, Series A-2 [Member] | MAC Trusts Share Repurchase Agreement [Member]
Share repurchase [Line Items]
Repurchase of common stock (in shares)			21,647,008
Common Class A, Series A-3 [Member] | MAC Trusts Share Repurchase Agreement [Member]
Share repurchase [Line Items]
Repurchase of common stock (in shares)			21,647,007
MAC Trusts [Member] | Common Class A, Series A-4 [Member]
Share repurchase [Line Items]
Repurchase of common stock (in shares)	21,300,000
Redemption price per share of common stock (in usd per share)	54.58
Payments for Repurchase of Common Stock	1,200,000,000

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Details) (USD $)	7 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2014		31-May-13		31-May-12
Sales And Receivables [Line Items]
Net sales	$4,765.90		$9,055.80		$9,974.10		$11,107.80
Receivables, net	543.1		754.4
Statement [Line Items]
Canadian resources taxes and royalties included in cost of goods sold	120.7		195		307.9		327.1
Assets related to PIS and Cofins and income tax credits in Brazil			74
Minimum [Member] | Machinery and Equipment [Member]
Statement [Line Items]
Useful life			3 years
Minimum [Member] | Land and Building [Member]
Statement [Line Items]
Useful life			3 years
Maximum [Member]
Statement [Line Items]
Duration of short term investments in number of days			90 days
Maximum [Member] | Machinery and Equipment [Member]
Statement [Line Items]
Useful life			25 years
Maximum [Member] | Land and Building [Member]
Statement [Line Items]
Useful life			40 years
Canpotex [Member]
Sales And Receivables [Line Items]
Net sales	439.7	[1]	923.6	[1]	1,239.80	[1]	1,298.90	[1]
Receivables, net	73.8		118
Phos Chem [Member]
Sales And Receivables [Line Items]
Net sales	$492				$1,300		$2,400
[1]	The export association of the Saskatchewan potash producers.

Other_Financial_Statement_Data2

Other Financial Statement Data (Details) (USD $)	7 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2014		31-May-13	31-May-12
Receivables [Abstract]
Trade	$460.10		$624.90
Non-trade	84.9		132.1
Current receivables, gross	545		757
Less: Allowance for doubtful accounts	1.9		2.6
Current receivables, net	543.1		754.4
Inventories
Raw materials	34		114.6
Work in process	433.6		505.1
Finished goods	891.6		1,025.50
Operating materials and supplies	73.7		73.1
Inventory, net	1,432.90		1,718.30
Other current assets
Final price deferred	154.3	[1]	49.9	[1]
Income and other taxes receivable	272.6		201.9
Prepaid expenses	115.8		63.8
Assets held for sale	111.9	[2]	6	[2]
Other	52.2		46.6
Total other current assets	706.8		368.2
Accrued liabilities
Non-income taxes	23.6		29.9
Payroll and employee benefits	111.8		172.8
Asset retirement obligations	86.3		87.9
Customer prepayments	131.9		101.6
Other	312.7		333.9
Total accrued liabilities, current	666.3		726.1
Other noncurrent liabilities
Asset retirement obligations	637.6		771.6
Accrued pension and postretirement benefits	69		77.6
Unrecognized tax benefits	96.3		89.2
Other	124.2		261.6
Total other noncurrent liabilities	927.1		1,200
Interest expense, net was comprised of the following:
Interest income	9.5		21.3		18.8	20.1
Less interest expense	22.8		128.9		0	1.4
Interest income (expense), net	($13.30)		($107.60)		$18.80	$18.70
[1]	Final price deferred is product that has shipped to customers, but the price has not yet been agreed upon. This has not been included in inventory as it is not held for sale.
[2]	See further description of assets held for sale in Footnote 22.

Property_Plant_and_Equipment_D

Property, Plant and Equipment (Details) (USD $)	7 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014	31-May-13	31-May-12
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	$12,601.60	$13,947.30
Less: accumulated depreciation and depletion	4,025	4,633.40
Property, plant and equipment, net	8,576.60	9,313.90
Depreciation, depletion and amortization expense and capitalized
Depreciation, depletion and amortization expense	386.2	750.9	604.8	508.1
Capitalized interest on major construction projects	25	34	52	55.7
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	188.6	233.7
Mining Properties and Mineral Rights [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	2,932.60	3,515.50
Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	1,969.50	2,242
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	5,994.10	6,660.60
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	$1,516.80	$1,295.50

Earnings_Per_Share_Details

Earnings Per Share (Details) (USD $)	7 Months Ended	12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014	31-May-13	31-May-12
Earnings Per Share [Abstract]
Net earnings attributable to Mosaic	$340	$1,028.60	$1,888.70	$1,930.20
Undistributed earnings attributable to participating securities	-4	-22.3	0	0
Numerator for basic and diluted earnings available to common stockholders	$336	$1,006.30	$1,888.70	$1,930.20
Basic weighted average number of shares outstanding	425.9	382.4	425.7	435.2
Shares subject to forward contract	-5.1	-8.3	0	0
Basic weighted-average number of shares outstanding attributable to common stockholders	420.8	374.1	425.7	435.2
Dilutive impact of share-based awards (in shares)	1.2	1.5	1.2	1.3
Diluted weighted average number of shares outstanding	422	375.6	426.9	436.5
Basic net earnings per share (in usd per share)	$0.80	$2.69	$4.44	$4.44
Diluted net earnings per share attributable to Mosaic (in usd per share)	$0.80	$2.68	$4.42	$4.42
Shares subject to issuance upon exercise of stock options, excluded from the calculation of diluted earnings per share	1.1	1.3	0.6	0.5

Cash_Flow_Information_Details

Cash Flow Information (Details) (USD $)	1 Months Ended	7 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Dec. 31, 2014	31-May-13	31-May-12
Interest Paid [Abstract]
Interest		$28.70	$155.90	$52	$76.70
Less amount capitalized		25	34	52	55.7
Cash interest, net		3.7	121.9	0	21
Income taxes		155.7	113.2	299.9	516.4
Increase (decrease) in accounts payable during the period reported in Investing Activities that arose from acquiring or constructing property, plant and equipment		87.7	29.3	54.6	56.7
Non-cash portion of the increase in equity method investements	$120

Investments_in_NonConsolidated1

Investments in Non-Consolidated Companies (Details)	Dec. 31, 2014
Equity Method Investee Gulf Sulphur Services [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest	50.00%
Equity Method Investee River Bend Ag [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest	50.00%
Equity Method Investee I F C [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest	45.00%
Equity Method Investee Yunnan Three Circles Sinochem Cargill Fertilizers [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest	35.00%
Equity Method Investee Miski Mayo Mine [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest	35.00%
Equity Method Investee Wa'ad Al Shamal Joint Venture [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest	25.00%
Equity Method Investee Canpotex [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest	38.80%

Investments_in_NonConsolidated2

Investments in Non-Consolidated Companies (Details 2) (USD $)	7 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014	31-May-13	31-May-12
Equity Method Investment, Summarized Financial Information, Income Statement [Abstract]
Net sales	$1,846.50	$3,814.10	$4,475.20	$4,938.40
Net earnings	12.1	20	67.5	97.9
Mosaicbs share of equity in net earnings (loss)	10.9	-2.2	18.3	13.3
Equity Method Investment Summarized Financial Information Balance Sheet [Abstract]
Total assets	1,658.50	4,344.90	1,841.40	1,776
Total liabilities	985.3	3,107	1,149.80	1,005
Mosaicbs share of equity in net assets	$250.90	$394	$256.40	$282.80

Investments_in_NonConsolidated3

Investments in Non-Consolidated Companies - Wa'ad Al Shamal Joint Venture (Details) (USD $)	1 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2014
		t
		financialinstitution
Schedule of Equity Method Investments [Line Items]
Non-cash portion of the increase in equity method investements	$120,000,000
Wa'ad Al Shamal Joint Venture [Member]
Schedule of Equity Method Investments [Line Items]
Aggregate cost of investment in phosphates greenfield mine including Mosaic's portion		7,500,000,000
Annual production of finished product (Tonnes)		3,500,000
Number of lenders in Wa'ad Al Shamal Joint Venture credit facility		20
Wa'ad Al Shamal Joint Venture line of credit facility, maximum borrowing capacity		5,000,000,000
Expected amount of subsidy from government		260,000,000
After project completion, number of months of shareholder tax amounts and severance fees for which the joint venture parties may have exposure		36 months
Future additional long term debt		560,000,000
Wa'ad Al Shamal Joint Venture [Member] | Maximum [Member]
Schedule of Equity Method Investments [Line Items]
Cash investment to acquire interest in Wa'ad Al Shamal Joint Venture		2,400,000,000
Mosaic Investment In Wa'ad Al Shamal Joint Venture [Member]
Schedule of Equity Method Investments [Line Items]
Percentage of joint venture production Mosaic expects to market		25.00%
Increase In Equity Method Investments		448,500,000
Non-cash portion of the increase in equity method investements		120,000,000
Mosaic Investment In Wa'ad Al Shamal Joint Venture [Member] | Maximum [Member]
Schedule of Equity Method Investments [Line Items]
Mosaic's exposure in Wa'ad Al Shamal Joint Venture credit facility		200,000,000
Cash investment to acquire interest in Wa'ad Al Shamal Joint Venture		$850,000,000

Goodwill_Details

Goodwill (Details) (USD $)	7 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014
Goodwill [Line Items]
Beginning balance	$1,844.60	$1,794.40
Foreign currency translation	-39.4	-94.1
Goodwill acquired in ADM acquisition		105.9
Reallocation of goodwill to assets held for sale	-10.8	0.3
Ending balance	1,794.40	1,806.50
Goodwill determined to be tax deductible		365.3
Phosphates Segment [Member]
Goodwill [Line Items]
Beginning balance	546.6	535.8
Foreign currency translation	0	1.6
Goodwill acquired in ADM acquisition		105.9
Reallocation of goodwill to assets held for sale	-10.8	5.1
Ending balance	535.8	648.4
Potash Segment [Member]
Goodwill [Line Items]
Beginning balance	1,298	1,258.60
Foreign currency translation	-39.4	-95.7
Goodwill acquired in ADM acquisition		0
Reallocation of goodwill to assets held for sale	0	-4.8
Ending balance	$1,258.60	$1,158.10

Financing_Arrangements_Shortte

Financing Arrangements - Short-term debt (Details) (USD $)	7 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2014	31-May-13	31-May-12
Short-term Debt [Line Items]
Total short-term debt	$22,600,000	$13,500,000
Line Of Credit [Member]
Short-term Debt [Line Items]
Credit facility term		5 years
The Mosaic Credit Facility amount available for revolving credit loans		1,500,000,000
Line of credit facility, expiration date		5-Dec-18
Letters of credit, amount outstanding	19,000,000	23,100,000
A failure to pay principal or interest under any one item of other indebtedness in excess of $50 million, or breach or default under such indebtedness that permits the holders thereof to accelerate the maturity thereof, will result in a cross-default in the Mosaic Credit Line		50,000,000
A failure to pay principal or interest for multiple items of other indebtedness in excess of $75 million, or breach or default under such indebtedness that permits the holders thereof to accelerate the maturity thereof, will result in a cross-default in the Mosaic Credit Line		75,000,000
Credit facility, debt to EBITDA ratio, maximum		3.5
Credit facility, interest coverage ratio, minimum		3
Total short-term debt	0	0
Net available borrowings for revolving loans under the Mosaic Credit Facility	1,481,000,000	1,476,900,000
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.19%	0.13%	0.20%	0.21%
Line of Credit Facility, Commitment Fee Amount	900,000	1,900,000	1,500,000	1,600,000
Short Term Debt [Member]
Short-term Debt [Line Items]
Total short-term debt		13,500,000
Stated interest rates as of the balance sheet date:
Stated interest rates - lowest rate		6.00%
Stated interest rates - highest rate		10.80%
Letter Of Credit [Member]
Short-term Debt [Line Items]
Letters of credit, amount outstanding		$7,100,000

Financing_Arrangements_Longter

Financing Arrangements - Long-term Debt (Details 2) (USD $)	0 Months Ended	12 Months Ended
	Nov. 07, 2013	Dec. 31, 2014	Dec. 31, 2013	Mar. 20, 2014
Debt Instrument [Line Items]
Stated value of issued debt		3,826,300,000	$3,017,400,000
Total Senior Notes due 2023, 2033 and 2043 [Member]
Debt Instrument [Line Items]
Stated value of issued debt	2,000,000,000
Net proceeds from offering	1,980,000,000
Notes Payable Due 2023 [Member]
Debt Instrument [Line Items]
Stated value of issued debt	900,000,000
Stated interest rate	4.25%
Notes Payable Due 2033 [Member]
Debt Instrument [Line Items]
Stated value of issued debt	500,000,000
Stated interest rate	5.45%
Notes Payable Due 2043 [Member]
Debt Instrument [Line Items]
Stated value of issued debt	600,000,000
Stated interest rate	5.63%
Notes Payable Due 2021 [Member]
Debt Instrument [Line Items]
Stated value of issued debt		450,000,000
Stated interest rate		3.75%
Notes Payable Due 2041 [Member]
Debt Instrument [Line Items]
Stated value of issued debt		300,000,000
Stated interest rate		4.88%
Debentures Due 2018 [Member]
Debt Instrument [Line Items]
Stated value of issued debt		89,000,000
Debentures Due 2028 [Member]
Debt Instrument [Line Items]
Stated value of issued debt		147,100,000
Term Loan A-1 [Member]
Debt Instrument [Line Items]
The Mosaic Credit Facility amount available for revolving credit loans				370,000,000
Long-term debt, percentage of principal repayments over the next twelve months		5.00%
Long-term debt, percentage of principal repayments in year two		5.00%
Term Loan A-2 [Member]
Debt Instrument [Line Items]
The Mosaic Credit Facility amount available for revolving credit loans				$430,000,000
Long-term debt, percentage of principal repayments over the next twelve months		5.00%
Long-term debt, percentage of principal repayments in year two		5.00%
Long-term debt, percentage of principal repayments in year three		7.50%
Long-term debt, percentage of principal repayments in year four		10.00%
Term Loans [Member]
Debt Instrument [Line Items]
Interest rate margin on LIBOR		1.13%

Financing_Arrangements_Longter1

Financing Arrangements - Long-term debt - Stated value (Details 3) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Long-term Debt, Excluding Current Maturities [Abstract]
Stated value of issued debt	$3,826,300,000	$3,017,400,000
Fair value adjustment of debt	2,800,000	3,100,000
Discount on Notes Issuance	-10,100,000	-11,200,000
Total	3,819,000,000	3,009,300,000
Stated value of current portion of issued debt	41,600,000	1,100,000
Fair value adjustment of current portion of long-term debt	400,000	400,000
Discount on Notes Issuance, current portion	-1,000,000	-1,100,000
Carrying Value, current portion	41,000,000	400,000
Stated value of noncurrent portion of issued debt	3,784,700,000	3,016,300,000
Fair Market Value Adjustment, Total long term debt noncurrent	2,400,000	2,700,000
Discount on Notes Issuance, Total long term debt noncurrent	-9,100,000	-10,100,000
Total long-term debt, less current maturities	3,778,000,000	3,008,900,000
Long-term Debt, Fiscal Year Maturity [Abstract]
2015	41,000,000
2016	43,700,000
2017	365,900,000
2018	132,400,000
2019	315,700,000
Thereafter	2,920,300,000
Total	3,819,000,000	3,009,300,000
Industrial Revenue Bond [Member]
Long-term Debt, Excluding Current Maturities [Abstract]
Stated value of issued debt	15,900,000	16,800,000
Fair value adjustment of debt	0	0
Discount on Notes Issuance	0	0
Total	15,900,000	16,800,000
Stated interest rates:
Stated interest rate	1.15%
Effective interest rate	1.15%
Long-term debt - other disclosures:
Maturity year	31-Dec-40
Long-term Debt, Fiscal Year Maturity [Abstract]
Total	15,900,000	16,800,000
Unsecured Notes [Member]
Long-term Debt, Excluding Current Maturities [Abstract]
Stated value of issued debt	2,750,000,000	2,750,000,000
Fair value adjustment of debt	0	0
Discount on Notes Issuance	-10,100,000	-11,200,000
Total	2,739,900,000	2,738,800,000
Stated interest rates:
Stated interest rates - lowest rate	3.75%
Stated interest rates - highest rate	5.63%
Effective interest rate	4.73%
Long-term debt - other disclosures:
Maturity year - earliest	1-Jan-21
Maturity year - latest	31-Dec-43
Long-term Debt, Fiscal Year Maturity [Abstract]
Total	2,739,900,000	2,738,800,000
Unsecured Debentures [Member]
Long-term Debt, Excluding Current Maturities [Abstract]
Stated value of issued debt	236,100,000	236,100,000
Fair value adjustment of debt	2,800,000	3,100,000
Discount on Notes Issuance	0	0
Total	238,900,000	239,200,000
Stated interest rates:
Stated interest rates - lowest rate	7.30%
Stated interest rates - highest rate	7.38%
Effective interest rate	7.08%
Long-term debt - other disclosures:
Maturity year - earliest	1-Jan-18
Maturity year - latest	31-Dec-28
Long-term Debt, Fiscal Year Maturity [Abstract]
Total	238,900,000	239,200,000
Term Loans [Member]
Long-term Debt, Excluding Current Maturities [Abstract]
Stated value of issued debt	800,000,000	0
Fair value adjustment of debt	0	0
Discount on Notes Issuance	0	0
Total	800,000,000	0
Stated interest rates:
Effective interest rate	1.28%
The reference rate for the variable rate of the Term Loans	LIBOR
Interest rate margin on LIBOR	1.13%
Long-term debt - other disclosures:
Maturity year - earliest	1-Jan-17
Maturity year - latest	1-Jan-19
Long-term Debt, Fiscal Year Maturity [Abstract]
Total	800,000,000	0
Other Types Of Debt [Member]
Long-term Debt, Excluding Current Maturities [Abstract]
Stated value of issued debt	24,300,000	14,500,000
Fair value adjustment of debt	0	0
Discount on Notes Issuance	0	0
Total	24,300,000	14,500,000
Stated interest rates:
Stated interest rates - lowest rate	2.50%
Stated interest rates - highest rate	9.00%
Effective interest rate	6.59%
Long-term debt - other disclosures:
Maturity year - earliest	1-Jan-14
Maturity year - latest	31-Dec-23
Long-term Debt, Fiscal Year Maturity [Abstract]
Total	$24,300,000	$14,500,000

Income_Taxes_Provision_for_tax

Income Taxes Provision for taxes (Details 1) (USD $)	7 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014	31-May-13	31-May-12
Current:
Federal	($25)	$46	$138.80	$314.50
State	-15.1	11.8	42.5	61
Non-U.S.	141.9	265.4	81.5	77
Total current	101.8	323.2	262.8	452.5
Deferred:
Federal	32.8	-103.6	-32.9	7.4
State	-0.3	-16.4	-14.1	9
Non-U.S.	18.3	-18.5	125.2	242.5
Total deferred	50.8	-138.5	78.2	258.9
Provision for income taxes	$152.60	$184.70	$341	$711.40

Income_Taxes_Effective_tax_rat

Income Taxes Effective tax rate (Details 2) (USD $)	7 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2014	31-May-13	31-May-12
The components of earnings from consolidated companies before income taxes, and the effects of significant adjustments to tax computed at the federal statutory rate, were as follows:
United States earnings	$208,200,000	$312,900,000	$1,158,100,000	$1,412,700,000
Non-U.S. earnings	276,000,000	904,400,000	1,056,400,000	1,216,200,000
Earnings from consolidated companies before income taxes	484,200,000	1,217,300,000	2,214,500,000	2,628,900,000
Effective Income Tax Rate Continuing Operations Tax Rate Reconciliation [Abstract]
Computed tax at the U.S. federal statutory rate of 35%	35.00%	35.00%	35.00%	35.00%
State and local income taxes, net of federal income tax benefit	1.20%	0.10%	1.60%	1.60%
Percentage depletion in excess of basis	-15.70%	-9.70%	-7.10%	-6.60%
Impact of non-U.S. earnings	3.80%	-3.80%	-10.20%	-2.90%
Non-taxable change in value of share repurchase agreement	-5.30%	1.70%	0.00%	0.00%
Change in valuation allowance	10.00%	-7.60%	-3.60%	0.40%
Other items (none in excess of 5% of computed tax)	2.50%	-0.50%	-0.30%	-0.40%
Effective tax rate	31.50%	15.20%	15.40%	27.10%
Income Tax Expense Benefit [Line Items]
Tax expense or benefit associated with repatriation of foreign earnings, which impacted the effective tax rate	100,800,000	81,000,000
Deferred tax benefit		47,000,000
Increase in income tax expense from foreign income tax settlements		8,100,000
Change in deferred tax assets valuation allowance		32,800,000
Other Tax Expense (Benefit)		53,600,000
Undistributed Earnings Of Non-U.S. Subsidiaries		2,200,000,000
APA Agreements [Member]
Income Tax Expense Benefit [Line Items]
Increase in income tax expense from foreign income tax settlements	4,000,000
Change in deferred tax assets valuation allowance		$11,700,000

Income_Taxes_Deferred_tax_Deta

Income Taxes Deferred tax (Details 3) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Deferred tax liabilities:
Depreciation and amortization	$897.90	$1,029.80
Depletion	397.9	388.6
Partnership tax basis differences	120.1	106.2
Undistributed earnings of non-U.S. subsidiaries	219.5	319.6
Other liabilities	41.5	150.9
Total deferred tax liabilities	1,676.90	1,995.10
Before valuation allowance
Alternative minimum tax credit carryforwards	144.5	113.8
Capital loss carryforwards	0	54.6
Foreign tax credit carryforwards	450.5	580.9
Net operating loss carryforwards	103.1	145.3
Pension plans and other benefits	29.1	17.1
Asset retirement obligations	263.7	260
Other assets	269.7	182.7
Subtotal	1,260.60	1,354.40
Valuation allowance	28.3	129.2
Net deferred tax assets	1,232.30	1,225.20
Net deferred tax liabilities	-444.6	-769.9
Deferred tax assets of both foreign and U.S. jurisdictions	$457	$384.90

Income_Taxes_Carryforwards_Det

Income Taxes Carryforwards (Details 4) (USD $)	12 Months Ended
	Dec. 31, 2014
Alternative Minimum Tax Credit Carryforward [Member]
Tax Carryforward [Line Items]
Tax credit carryforward	$144,500,000
Net Operating Loss Carryforward [Member]
Tax Carryforward [Line Items]
Maximum percentage of annual taxable income allowed to use of the tax credit carryforward	30.00%
Net operating loss	343,100,000
Foreign Tax Credit Carryforward [Member]
Tax Carryforward [Line Items]
Tax credit carryforward	450,500,000
Future taxable income needed to fully utilize carryforwards	1,300,000,000
Foreign Tax Credit Carryforward [Member] | Expiration date less than 5 years [Member]
Tax Carryforward [Line Items]
Tax credit carryforward	$350,000,000

Income_Taxes_Valuation_Allowan

Income Taxes Valuation Allowances & Uncertain Tax Provisions (Details 5) (USD $)	7 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014	31-May-13	31-May-12
Changes in unrecognized tax benefits for all jurisdictions were as follows:
Gross unrecognized tax benefits, beginning of period	$316.80	$99.20	$476.90
Prior year tax positions - increases	128.5	33	7.7
Current year tax positions	0.4	2.8	36.6
Prior year tax positions - decreases	-24	0	-204.3
Settlements	-323.7	-32.6	0
Currency translation	1.2	-1.8	-0.1
Gross unrecognized tax benefits, end of period	99.2	100.6	316.8	476.9
The amount of unrecognized tax benefits that, if recognized, would affect our effective tax rate in future periods		100
Accrued interest and penalties related to unrecognized tax benefits, which are reflected in other noncurrent liabilities	28.8	20
Valuation Allowance [Abstract]
Net change in the deferred tax asset valuation allowance during the period	35.4	-100.9	-86.6	-29
Change in deferred tax assets valuation allowance		32.8
Foreign Country [Member]
Changes in unrecognized tax benefits for all jurisdictions were as follows:
Prior year tax positions - increases		21.3
Resolution of certain tax matters [Member]
Changes in unrecognized tax benefits for all jurisdictions were as follows:
Prior year tax positions - decreases			-179.3
APA Agreements [Member]
Changes in unrecognized tax benefits for all jurisdictions were as follows:
Settlements		-8.1
Valuation Allowance [Abstract]
Change in deferred tax assets valuation allowance		$11.70

Accounting_for_Asset_Retiremen2

Accounting for Asset Retirement Obligations (Details) (USD $)	7 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014	31-May-13	31-May-12
Asset Retirement Obligation Disclosure [Abstract]
Asset retirement obligations, beginning of period	$658.50	$723.90
Liabilities acquired in CF Phosphate Assets Acquisition	0	145.6
Liabilities incurred	13.6	21.7
Liabilities settled	-37	-91.1
Accretion expense	21.6	42.1	33.3	32.4
Revisions in estimated cash flows	67.2	17.3
Asset retirement obligations, end of period	723.9	859.5	658.5
Less current portion	86.3	87.9
Asset retirement obligations	$637.60	$771.60

Derivatives_Gross_Assets_and_L

Derivatives - Gross Assets and Liabilities Positions (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross asset position	$9	$7.90
Gross liability position	$54.80	$20.40

Derivative_Notional_Amounts_De

Derivative - Notional Amounts (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative, notional amount	$1,132.30	$940.20
Commodity Contract (MMbtu) [Member]
Derivative [Line Items]
Derivative, nonmonetary notional amount	24,400,000	8,200,000

Derivatives_Credit_Risk_Relate

Derivatives - Credit Risk Related Contingent Features (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Derivative, Credit Risk Related Contingent Features [Abstract]
The aggregate fair value of all derivative instruments with credit-risk-related contingent features that were in a liability position	$41.70	$12.30
Required collateral assets to be posted if the credit-risk contingent features of these underlying agreements were triggered.	$40.70

Fair_Value_Measurements_Detail

Fair Value Measurements (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Gross asset position	$9	$7.90
Gross liability position	54.8	20.4
Fair Value, Measurements, Recurring [Member] | Foreign Exchange Contract [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Gross asset position	4.6	0.6
Gross liability position	39.8	18.1
Fair Value, Measurements, Recurring [Member] | Commodity Contract (MMbtu) [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Gross asset position	4.4	6
Gross liability position	$14.90	$2

Fair_Value_Financial_Instrumen

Fair Value Financial Instruments (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Carrying amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$2,374.60	$5,293.10
Accounts Receivable	754.4	543.1
Accounts payable trade	797.3	570.2
Short-term debt	13.5	22.6
Long-term debt, including current portion	3,819	3,009.30
Fair value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	2,374.60	5,293.10
Accounts Receivable	754.4	543.1
Accounts payable trade	797.3	570.2
Short-term debt	13.5	22.6
Long-term debt, including current portion	$4,101.20	$3,059.60

Guarantees_and_Indemnities_Det

Guarantees and Indemnities (Details) (USD $)	Dec. 31, 2014
In Millions, unless otherwise specified
Guarantees [Abstract]
Guarantee Obligations Maximum Exposure	$63.60

Pension_Plans_and_Other_Benefi2

Pension Plans and Other Benefits - Changes in Defined Benefit Obligations and Plan Assets (Details) (USD $)	7 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014	31-May-13	31-May-12
Change in plan assets:
Fair value at end of period	$736.90	$812.10
Amounts recognized in the consolidated balance sheets:
Noncurrent liabilities	-69	-77.6
Amounts recognized in accumulated other comprehensive (income) loss
Accumulated benefit obligation for the defined benefit pension plans	724	823.7
North American Pension Plans [Member]
Change in projected benefit obligation:
Benefit obligation at beginning of period	788.6	728
Service cost	4.6	6.3	6.5	5.6
Interest cost	19	32.8	32.6	34.5
Actuarial (gain) loss	-49.3	124.8
Currency fluctuations	-11.8	-26.8
Benefits paid	-23.1	-42.1
Special termination costs	0	5.4	0	0
Projected benefit obligation at end of period	728	828.4	788.6
Change in plan assets:
Fair value at beginning of period	707.6	736.9
Currency fluctuations	-9.1	-26.3
Actual return	18.8	110.7
Company contribution	42.7	32.9
Benefits paid	-23.1	-42.1
Fair value at end of period	736.9	812.1	707.6
Funded/(unfunded) status of the plans as of the end of period	8.9	-16.3
Amounts recognized in the consolidated balance sheets:
Noncurrent assets	30.2	10.1
Current liabilities	-0.6	-0.6
Noncurrent liabilities	-20.7	-25.8
Amounts recognized in accumulated other comprehensive (income) loss
Prior service costs (credits)	24.9	18.7
Actuarial (gain) loss	73.1	120.6
North American Postretirement Benefit Plans [Member]
Change in projected benefit obligation:
Projected benefit obligation at end of period	$52.80	$56.20

Pension_Plans_and_Other_Benefi3

Pension Plans and Other Benefits - Changes in Net Periodic Pension Cost (Details) (North American Pension Plans [Member], USD $)	7 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014	31-May-13	31-May-12
North American Pension Plans [Member]
Net Periodic Benefit Cost Before Settlements:
Service cost	$4.60	$6.30	$6.50	$5.60
Interest cost	19	32.8	32.6	34.5
Expected return on plan assets	-25.1	-44	-37.3	-35.8
Prior service cost/(credit)	1.4	1.9	1.3	1.3
Actuarial (gain)/loss	5.4	4.7	16.1	13.4
Preliminary net periodic benefit cost	5.3	1.7	19.2	19
Curtailment expense	0	2.3	0	0
Special termination costs	0	5.4	0	0
Total net periodic benefit cost	5.3	9.4	19.2	19
Other Changes In Plan Assets And Benefit Obligations Recognized In Other Comprehensive Income [Abstract]
Prior service cost (credit) recognized in other comprehensive income	-1.3	-1.9	14.1	-1.3
Net actuarial loss (gain) recognized in other comprehensive income	-48.5	53.3	-5.9	36.3
Total recognized in other comprehensive income	-49.8	51.4	8.2	35
Total recognized in net periodic benefit (income) cost and other comprehensive income	-44.5	60.8	27.4	54
The estimated net actuarial (gain) loss and prior service cost (credit) for the pension plans that will be amortized from accumulated other comprehensive income into net periodic benefit cost in the next fiscal year		$9.20

Pension_Plans_and_Other_Benefi4

Pension Plans and Other Benefits - Est Future Defined Benefit Pension Plan Pmts (Details) (USD $)	Dec. 31, 2014
In Millions, unless otherwise specified
Medicare D Adjustments [Abstract]
2015	$0.60
2016	0.6
2017	0.6
2018	0.6
2019	0.6
2020-2024	1.9
North American Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
2015	42.2
2016	43.4
2017	44.3
2018	45.9
2019	47.3
2020-2024	247.8
North American Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
2015	5.8
2016	5.8
2017	5.5
2018	5.1
2019	4.5
2020-2024	$16.90

Pension_Plans_and_Other_Benefi5

Pension Plans and Other Benefits - Other Disclosures (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
The amount of estimated cash contribution to the defined benefit pension plans needed next fiscal year to meet minimum funding requirements	$14.60
The amount of cash contribution to the defined benefit postretirement medical plans needed next fiscal year to meet minimum funding requirements	$5.80

Pension_Plans_and_Other_Benefi6

Pension Plans and Other Benefits - Plan Asset Allocations (Details)	12 Months Ended
	Dec. 31, 2014
United States Pension Plan of US Entity [Member] | Fixed Income Securities [Member]
Summary Target Allocation Strategy [Abstract]
Overall investment strategy- target allocation percentages	75.00%
United States Pension Plan of US Entity [Member] | Return Seeking Investments Member [Member]
Summary Target Allocation Strategy [Abstract]
Overall investment strategy- target allocation percentages	25.00%
Foreign Pension Plans Defined Benefit [Member]
Summary Target Allocation Strategy [Abstract]
Percentage over annualized rate of return of the consumer price index	5.00%
Foreign Pension Plans Defined Benefit [Member] | Fixed Income Securities [Member]
Summary Target Allocation Strategy [Abstract]
Overall investment strategy- target allocation percentages	40.00%
Foreign Pension Plans Defined Benefit [Member] | Return Seeking Investments Member [Member]
Summary Target Allocation Strategy [Abstract]
Overall investment strategy- target allocation percentages	60.00%
Minimum [Member] | Foreign Pension Plans Defined Benefit [Member]
Summary Target Allocation Strategy [Abstract]
Nominal annualized rate of return equal to or greater than the actuarially assumed investment return period	10 years
Annualized rate of return of the Consumer Price Index period	10 years
Annualized rates of return consistent with or in excess of specific respective market benchmarks at the individual asset class level period	3 years
Maximum [Member] | Foreign Pension Plans Defined Benefit [Member]
Summary Target Allocation Strategy [Abstract]
Nominal annualized rate of return equal to or greater than the actuarially assumed investment return period	20 years
Annualized rate of return of the Consumer Price Index period	20 years
Annualized rates of return consistent with or in excess of specific respective market benchmarks at the individual asset class level period	5 years

Pension_Plans_and_Other_Benefi7

Pension Plans and Other Benefits - Plan Asset FV Measurements (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	$812.10		$736.90
Fair Value Inputs Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	8.6		9.8
Fair Value Inputs Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	777.8		696.7
Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	25.7		30.4
Cash And Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	8.6		9.8
Cash And Cash Equivalents [Member] | Fair Value Inputs Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	8.6		9.8
Cash And Cash Equivalents [Member] | Fair Value Inputs Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	0		0
Cash And Cash Equivalents [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	0		0
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	302.2	[1]	281.1	[1]
Equity Securities [Member] | Fair Value Inputs Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	0	[1]	0	[1]
Equity Securities [Member] | Fair Value Inputs Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	285.9	[1]	262.8	[1]
Equity Securities [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	16.3	[1]	18.3	[1]
Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	491.9	[2]	433.9	[2]
Fixed Income Securities [Member] | Fair Value Inputs Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	0	[2]	0	[2]
Fixed Income Securities [Member] | Fair Value Inputs Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	491.9	[2]	433.9	[2]
Fixed Income Securities [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	0	[2]	0	[2]
Private Equity Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	9.4		12.1
Private Equity Funds [Member] | Fair Value Inputs Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	0		0
Private Equity Funds [Member] | Fair Value Inputs Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	0		0
Private Equity Funds [Member] | Fair Value Inputs Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	$9.40		$12.10
[1]	This class includes several funds that are invested approximately 46% in U.S. equity securities, 26% in international equity securities, 23% in Canadian equity securities, and 5% in other real estate securities.
[2]	This class includes several funds that are invested approximately 57% in corporate debt securities, 22% in other governmental securities in the U.S. and Canada, 13% in U.S. government debt securities, 5% in foreign entity debt securities and 3% in Canadian government securities.

Pension_Plans_and_Other_Benefi8

Pension Plans and Other Benefits - Plan Asset Fair Values (Details)	12 Months Ended
	Dec. 31, 2014
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
U.S. Equity securities - percentage	46.00%
International equity securities - percentage	26.00%
Canadian equity securities - percentage	23.00%
Other real estate equity securties - percentage	5.00%
Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Corporate debt securities - percentage	57.00%
Other governmental securities in the U.S. and Canada - percentage	22.00%
U.S. government debt securities - percentage	13.00%
Debt securities issued by entities foreign to USA - percentage	5.00%
Canadian government securities - percentage	3.00%

Pension_Plans_and_Other_Benefi9

Pension Plans and Other Benefits - Fair Value Assumptions (Details) (North American Pension Plans [Member])	7 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2014	31-May-13	31-May-12
North American Pension Plans [Member]
The assumptions used to determine benefit obligations were as follows:
Discount rate	4.75%	3.95%	4.25%	4.44%
Expected return on plan assets	6.15%	6.15%	6.13%	6.29%
Rate of compensation increase	3.50%	3.50%	4.00%	4.00%
The assumptions used to determine net benefit cost were as follows:
Discount rate	4.25%	4.75%	4.44%	5.13%
Expected return on plan assets	6.13%	6.15%	6.29%	6.87%
Rate of compensation increase	4.00%	3.50%	4.00%	4.00%

Recovered_Sheet2

Pension Plans and Other Benefits - Defined Contribution Plans (Details) (USD $)	7 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014	31-May-13	31-May-12
Defined Contribution Pension and Other Postretirement Plans Disclosure [Abstract]
Mosaic's matching rate of first tier of employee's compensation deferrals under the "Investment Plan"		100.00%
Maximum rate of first tier of deferred compensation elected by employees under the Company's "Investment Plan"		3.00%
Mosaic's matching rate of second tier of employee's compensation deferrals under the "Investment Plan"		50.00%
Maximum rate of second tier of deferred compensation elected by employees under the Company's "Investment Plan"		3.00%
Expense attributable to the Company's Investment Plan and Savings Plan	$30.20	$51.50	$47.30	$41.20

Sharebased_Payments_Details

Share-based Payments (Details)	Dec. 31, 2014
Omnibus Stock and Incentive Plan 2004 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares and share options to employees	25,000,000
2014 Mosaic Stock and Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares and share options to employees	25,000,000

Sharebased_Payments_Stock_Opti

Share-based Payments, Stock Options (Details 2) (USD $)	7 Months Ended	12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014	31-May-13	31-May-12
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
The weighted-average grant date fair value of options granted during the fiscal year (in usd per share)	$20.87	$18.79	$22.71	$30.96
The total intrinsic value of options exercised during the fiscal year	$1.30	$9.40	$6.80	$5.50
Stock Options [Member]
Assumptions used to calculate the fair value of stock options in each period are noted in the following table. A summary of the assumptions used to estimate the fair value of stock option awards is as follows:
Expected volatility (percent)	43.87%	42.40%	47.70%	51.80%
Expected dividend yield (percent)	1.85%	2.01%	1.74%	0.28%
Expected term (in years)	7 years	7 years	7 years	5 years
Risk-free interest rate (percent)	1.99%	2.31%	0.92%	1.46%
Shares (in millions)
Number of option shares outstanding at beginning of period (in shares)		2.6
Granted (in shares)		0.2
Exercised (in shares)		-0.4
Number of option shares outstanding at end of period (in shares)	2.6	2.4
Number of shares issuable under options exercisable at end of period (in shares)		2
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted average exercise price- options outstanding at beginning of period (in usd per share)		$44.82
Granted (in usd per share)		$49.73
Exercised (in usd per share)		$18.91
Weighted Average Exercise Price- options outstanding at end of period (in usd per share)	$44.82	$48.88
Weighted Average Exercise Price- options exercisable at end of period (in usd per share)		$48.16
Weighted Average Remaining Contractual Term (Years) - options outstanding at beginning of period	5 years	4 years 9 months 18 days
Weighted Average Remaining Contractual Term (Years) - options outstanding at end of period	5 years	4 years 9 months 18 days
Weighted Average Remaining Contractual Term (Years) - options exercisable as of the end of the fiscal year		4 years
Aggregate Intrinsic Value - options outstanding at beginning of period		28
Aggregate Intrinsic Value - options outstanding at end of period	28	16
Aggregate Intrinsic Value - options exercisable as of the end of the fiscal year		$16

Sharebased_Payments_RSUs_Detai

Share-based Payments, RSU's (Details 3) (Restricted Stock Units R S U [Member], USD $)	12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2014
Restricted Stock Units R S U [Member]
Shares (in millions)
Number of stock units outstanding at beginning of period (shares)	0.8
Granted (in shares)	0.6
Issued and canceled (shares)	-0.4
Number of stock units outstanding at end of period (shares)	1
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted-average grant date fair value per share - stock unit awards outstanding, beginning of period (in usd per share)	$57.50
Granted (in usd per share)	$48.72
Issued and canceled (in usd per share)	$55.51
Weighted-average grant date fair value per share - stock unit awards outstanding, end of period (in usd per share)	$53.12

Sharebased_Peyments_PSUs_Detai

Share-based Peyments, PSU's (Details 4) (USD $)	7 Months Ended	12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014	31-May-13	31-May-12
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Share-based compensation expense, net of forfeitures, in the fiscal year	$25.10	$57.20	$32.20	$25.20
The tax benefit related to share-based compensation expense in the fiscal year	8.4	19.8	11.4	8.7
Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized		31.6
The average weighted-average period the unrecognized compesation cost will be recognized (years)		1 year
The total fair value of options vested during the fiscal year	7.1	5.5	9.5	10.2
Cash received from exercise of all share-based payment arrangements	1.1	6.7	6	3
Tax benefit for tax deductions from options during the fiscal year	$4.40	$10.20	$6.40	$3.70
Performance Stock Unit [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Minimum retirement age for performance units to vest		60 years
Number of trading days to calculate weighted average stock price		30 days
Expected volatility (percent)	32.78%	30.39%	38.05%	54.72%
Expected dividend yield (percent)	1.85%	2.08%	1.74%	0.28%
Expected term (in years)	3 years	3 years	3 years	3 years
Risk-free interest rate (percent)	0.61%	0.77%	0.31%	0.69%
Shares (in millions)
Number of stock units outstanding at beginning of period (shares)		0.4
Granted (in shares)		0.1
Number of stock units outstanding at end of period (shares)	0.4	0.5
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted-average grant date fair value per share - stock unit awards outstanding, beginning of period (in usd per share)		$69.64
Weighted Average Grant Date Fair Value Per Share, Granted (in usd per share)		$61.11
Weighted-average grant date fair value per share - stock unit awards outstanding, end of period (in usd per share)	$69.64	$64.31

Commitments_Details

Commitments (Details) (USD $)	7 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2014	31-May-13	31-May-12
Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract]
2015		$2,420,600,000
2016		532,400,000
2017		422,100,000
2018		364,900,000
2019		366,000,000
Subsequent years		4,189,400,000
Total		8,295,400,000
A schedule of future minimum lease payments under non-cancelable operating leases follows:
2015		58,000,000
2016		50,100,000
2017		43,900,000
2018		34,500,000
2019		29,100,000
Subsequent years		90,600,000
Total		306,200,000
Rental expense and purchases made for the fiscal period were as follows:
Rental expense for the fiscal period	56,500,000	108,900,000	88,800,000	80,000,000
Purchases made under long-term commitments during the reporting period	1,200,000,000	2,300,000,000	2,700,000,000	3,100,000,000
Surety Bonds Outstanding [Abstract]
Total amount of surety bonds outstanding		179,900,000
Surety bonds outstanding for mining reclamation obligations		170,100,000
Surety bonds outstanding for other than mining reclamation obligations		$9,800,000

Contingencies_Details

Contingencies (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	31-May-13
Applicability, Impact and Conclusion of Environmental Loss Contingencies [Abstract]
Environmental contingency accrual	$32,500,000	$31,300,000
Loss Contingencies [Line Items]
Number Of Specified Mineral Processing Wastes Exempted From EPA Rules	20
Discounted asset retirement obligation	859,500,000	723,900,000	658,500,000
Unfavorable Regulatory Action [Member]
Loss Contingencies [Line Items]
Future capital expenditures	150,000,000
Recorded third-party environmental recoveries	1,700,000,000
Discounted asset retirement obligation	543,000,000
Estimated assets held in trust	625,000,000
Brazilian Non Income Tax Proceedings [Member]
Loss Contingencies [Line Items]
Maximum potential liability	91,000,000
Brazilian Non Income Tax Proceedings [Member] | PIS And Cofins Cases [Member]
Loss Contingencies [Line Items]
Maximum potential liability	$50,000,000

Related_Party_Transactions_Det

Related Party Transactions (Details) (USD $)	7 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014	31-May-13	31-May-12
Related Party Transactions [Abstract]
Net amount due from our non-consolidated companies	$52.60	$35.70
Transactions with non-consolidated companies included in net sales	448.8	946	1,263.90	1,321.20
Transactions with non-consolidated companies included in cost of goods sold	$257.50	$532.80	$632	$557.30

Disposal_Activities_Details

Disposal Activities (Details) (USD $)	7 Months Ended		12 Months Ended				3 Months Ended			0 Months Ended	3 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2014		31-May-13	31-May-12	Dec. 31, 2014		Jun. 30, 2014	Jul. 29, 2014	Sep. 30, 2013
Long Lived Assets Held-for-sale [Line Items]
Related tax benefits			($53.60)
(Gain) loss on assets sold and to be sold	-122.8		16.4		0	0
Assets held for sale	111.9	[1]	6	[1]			6	[1]
Proceeds from sale of businesses	0		81.4		0	0
Argentina And Chile Distribution Businesses [Member]
Long Lived Assets Held-for-sale [Line Items]
Restructuring and other charges	50
Argentina Distribution Business [Member]
Long Lived Assets Held-for-sale [Line Items]
Related tax benefits			53.6
(Gain) loss on assets sold and to be sold							8.5
Chile Distribution Business [Member]
Long Lived Assets Held-for-sale [Line Items]
(Gain) loss on assets sold and to be sold									-5.6
Assets held for sale			6				6
Hersey Mine [Member]
Long Lived Assets Held-for-sale [Line Items]
Restructuring and other charges											48
Related tax benefits	17
(Gain) loss on assets sold and to be sold			13.5
Proceeds from sale of businesses										$55
[1]	See further description of assets held for sale in Footnote 22.

Exit_Activities_Details

Exit Activities (Details) (USD $)	7 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014	31-May-13	31-May-12
Restructuring Cost and Reserve [Line Items]
Carlsbad restructuring expense	$0	$125.40	$0	$0
Related tax benefits		-53.6
Hookers Prairie Mine Closing [Member]
Restructuring Cost and Reserve [Line Items]
Severance charges		11
Payments related to severance charges		9
Discontinued MOP Production at Carlsbad Facility [Member]
Restructuring Cost and Reserve [Line Items]
Carlsbad restructuring expense		125.4
Accelerated depreciation and depletion		100
Related tax benefits		$52

Acquisitions_CF_Phosphate_Asse

Acquisitions CF Phosphate Assets Acquisition (Details) (USD $)	7 Months Ended	12 Months Ended			3 Months Ended		0 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014	31-May-13	31-May-12	Dec. 31, 2014	Dec. 31, 2015	Mar. 17, 2014
Business Acquisition [Line Items]
Effective date of acquisition		17-Mar-14
Business Combination, Consideration Transferred
Payment for acquisition	$0	$1,725.40	$0	$0
Asset Retirement Obligation [Abstract]
Discounted asset retirement obligation	723.9	859.5	658.5		859.5
Inventories At Price Tied To Natural Gas [Member]
Long-term Purchase Commitment [Line Items]
Purchase commitment, minimum quantity		545,000
Purchase commitment, maximum quantity		725,000
Inventories At Price Tied To C F R Tampa Price [Member]
Long-term Purchase Commitment [Line Items]
Purchase commitment, minimum quantity		270,000
CF Phosphate Assets Acquisition [Member]
Business Combination, Consideration Transferred
Payment for acquisition		1,375.80
Plant City Trust [Member]
Restricted Cash and Investments, Noncurrent [Abstract]
Funds for asset retirement obligation		189.2			189.2
Increase in funds for asset retirement obligation					7
Bonnie Facility Trust [Member]
Restricted Cash and Investments, Noncurrent [Abstract]
Funds for asset retirement obligation		14.5			14.5
Bonnie Facility Trust [Member] | Estimate [Member]
Restricted Cash and Investments, Noncurrent [Abstract]
Increase in funds for asset retirement obligation						4
C F Florida Phosphates Assets [Member]
Business Combination, Consideration Transferred
Payment for acquisition							1,172.10
C F Asset Retirement Obligations [Member]
Business Combination, Consideration Transferred
Payment for acquisition							203.7
Asset Retirement Obligation [Abstract]
Discounted asset retirement obligation		$103.50			$103.50

Acquisitions_Purchase_Price_Al

Acquisitions Purchase Price Allocation (Details) (USD $)	7 Months Ended	12 Months Ended				0 Months Ended	3 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014		31-May-13	31-May-12	Dec. 17, 2014	Mar. 31, 2015
Business Acquisition [Line Items]
Goodwill	$1,794.40	$1,806.50		$1,844.60
Payment for acquisition	0	1,725.40		0	0
CF Phosphate Assets Acquisition [Member]
Business Acquisition [Line Items]
Inventory		144.1
Other current assets		0.5
Mineral properties and rights		499.7
Property, plant, and equipment		627.1
Funds for asset retirement obligations		203.7	[1]
Other assets		56.8
Current Liabilities		-1.5
Other liabilities		-9
Asset retirement obligation		-145.6
Total Assets Acquired and Liabilities Assumed, Net		1,375.80
Payment for acquisition		1,375.80
Brazil and Paraguay Distribution Business Acquisition [Member]
Business Acquisition [Line Items]
Inventory		122.5
Other current assets		10.3
Property, plant, and equipment		95.1
Goodwill		105.9
Other assets		18.6
Accounts payable		-19.2
Other current liabilities		-24.2
Payment for acquisition		349.6
Initial Agreed Amounts
Value of acquisition						350
Working capital acquired, delivery at closing						150
Brazil and Paraguay Distribution Business Acquisition [Member] | Estimate [Member]
Business Combination, Consideration To Be Transferred
Estimated value of acquisition							309
Expected post closing working capital adjustment							$40.60
[1]	(1) Included with other assets in the Consolidated Balance Sheet as of December 31, 2014

Acquisitions_Cost_and_Revenue_

Acquisitions Cost and Revenue Since Acquisition (Details) (USD $)	9 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2014
CF Phosphate Assets Acquisition [Member]
Business Acquisition [Line Items]
Acquisition related costs		$8.70
Revenue since acquisition	574.2
Earnings (loss) since acquisition	37.6
Brazil and Paraguay Distribution Business Acquisition [Member]
Business Acquisition [Line Items]
Acquisition related costs		$2.90

Acquisitions_Pro_Forma_Results

Acquisitions Pro Forma Results (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition, Pro Forma Information [Abstract]
Pro-forma net sales	$9,947.70	$10,820.90
Pro-forma net earnings attributable to Mosaic	$1,014.60	$1,079.80

Business_Segments_Details

Business Segments (Details) (USD $)	7 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014	31-May-13	31-May-12
Segment Reporting Information [Line Items]
Net sales	$4,765.90	$9,055.80	$9,974.10	$11,107.80
Gross margin	828.3	1,926.60	2,760.20	3,085
Carlsbad restructuring expense	0	125.4	0	0
Operating earnings (loss)	416.9	1,311.80	2,209.60	2,611.10
Capital expenditures	800	929.1	1,588.30	1,639.30
Depreciation, depletion and amortization expense	386.2	750.9	604.8	508.1
Equity in net earnings of non consolidated companies	10.9	-2.2	18.3	13.3
Total assets	19,554	18,283
Phosphates Segment [Member]
Segment Reporting Information [Line Items]
Net sales	3,438.20	6,194	6,494.60	7,839.20
Gross margin	445	1,071.20	1,162.20	1,466.90
Carlsbad restructuring expense		0
Operating earnings (loss)	199.7	766.7	848.1	1,179.10
Capital expenditures	298.7	439	427.5	407.9
Depreciation, depletion and amortization expense	177.2	368.9	287.3	263.9
Equity in net earnings of non consolidated companies	10.1	-4.6	16.4	11.9
Total assets	9,945.10	11,392.20
Phosphates Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	3,438.20	6,194	6,494.60	7,839.20
Phosphates Segment [Member] | Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Net sales	0	0	0	0
Potash Segment [Member]
Segment Reporting Information [Line Items]
Net sales	1,387.20	2,851.60	3,529.30	3,301.30
Gross margin	374.3	897.7	1,611.30	1,622
Carlsbad restructuring expense		125.4
Operating earnings (loss)	224.6	630.6	1,393	1,457.30
Capital expenditures	471	470.7	1,017.70	1,171.40
Depreciation, depletion and amortization expense	197.2	355.1	301.9	233.1
Equity in net earnings of non consolidated companies	0	0	0	0
Total assets	9,597.40	8,296.60
Potash Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	1,323.90	2,839.90	3,469.10	3,263.10
Potash Segment [Member] | Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Net sales	63.3	11.7	60.2	38.2
Corporate Eliminations And Other Segment [Member]
Segment Reporting Information [Line Items]
Net sales	-59.5	10.2	-49.8	-32.7
Gross margin	9	-42.3	-13.3	-3.9
Carlsbad restructuring expense		0
Operating earnings (loss)	-7.4	-85.5	-31.5	-25.3
Capital expenditures	30.3	19.4	143.1	60
Depreciation, depletion and amortization expense	11.8	26.9	15.6	11.1
Equity in net earnings of non consolidated companies	0.8	2.4	1.9	1.4
Total assets	11.5	-1,405.80
Corporate Eliminations And Other Segment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	3.8	21.9	10.4	5.5
Corporate Eliminations And Other Segment [Member] | Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Net sales	($63.30)	($11.70)	($60.20)	($38.20)

Business_Segments_Details_2

Business Segments (Details 2) (USD $)	7 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2014		31-May-13		31-May-12
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	$4,765.90		$9,055.80		$9,974.10		$11,107.80
Long-lived assets	9,501.60		10,717.90
Goodwill	1,794.40		1,806.50		1,844.60
Deferred income taxes	152.2		394.4
Brazil [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	1,249.80		1,921.40		2,069.30		2,161.60
Long-lived assets	122.2		257.6
Canpotex [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	439.7	[1]	923.6	[1]	1,239.80	[1]	1,298.90	[1]
Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	259.7		663.1		686.3		786.3
Long-lived assets	5,372.30		4,993
India [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	315.8		331.9		475.2		1,579.70
Australia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	31.2		194.7		177.5		290.1
China [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	86.9		191.1		173.3		160.4
Argentina [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	163.1		167.3		258.3		266.7
Colombia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	55.2		145		143.5		155.9
Japan [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	75.9		131.5		188.2		177.5
Mexico [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	22.4		131.3		128.9		90.5
Peru [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	35.6		101.8		56.9		95.1
Chile [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	76.9		44.6		116.5		121.1
Thailand [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	28.7		40.8		88.9		94
Other Foreign [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	72.4		223.7		271.7		209.3
Long-lived assets	51		22.5
Total Foreign [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	2,913.30		5,211.80		6,074.30		7,487.10
Long-lived assets	5,545.50		5,273.10
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	1,852.60		3,844		3,899.80		3,620.70
Long-lived assets	$3,956.10		$5,444.80
[1]	The export association of the Saskatchewan potash producers.

Business_Segments_Details_3

Business Segments (Details 3) (USD $)	7 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2014		31-May-13		31-May-12
Revenue from External Customer [Line Items]
Net sales	$4,765.90		$9,055.80		$9,974.10		$11,107.80
Phosphate Crop Nutrients [Member]
Revenue from External Customer [Line Items]
Net sales	2,059.30		4,096.20		4,106.10		5,418.40
Potash Crop Nutrients [Member]
Revenue from External Customer [Line Items]
Net sales	1,312.30		2,828.80		3,434.50		3,174.40
Crop Nutrient Blends [Member]
Revenue from External Customer [Line Items]
Net sales	863.7		1,292.90		1,472.30		1,517.10
Other [Member]
Revenue from External Customer [Line Items]
Net sales	$530.60	[1]	$837.90	[1]	$961.20	[1]	$997.90	[1]
[1]	Includes sales for animal feed ingredients and industrial potash.

Schedule_II_Valuation_and_Qual1

Schedule II Valuation and Qualifying Accounts (Details) (USD $)	7 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2014		31-May-13		31-May-12
Allowance For Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance Beginning of Period	$16	[1]	$10.40	[1]	$18.40	[1]	$23.60
Charges or (Reductions) to Costs and Expenses	-0.9		1.7		-1		0
Charges or (Reductions) to Other Accounts(a)(b)	-3	[2],[3]	1.8	[2],[3]	-1.3	[2],[3]	-5.1	[2],[3]
Deductions	-1.7		-1.8		-0.1		-0.1
Balance at End of Period(c)	10.4	[1]	12.1	[1]	16	[1]	18.4	[1]
Valuation Allowance Of Deferred Tax Assets [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance Beginning of Period	93.6	[1]	129.2	[1]	180.2	[1]	209.2
Charges or (Reductions) to Costs and Expenses	48.1		-73.1		-77.7		6.2
Charges or (Reductions) to Other Accounts(a)(b)	-12.5	[2],[3]	-27.8	[2],[3]	-8.9	[2],[3]	-35.2	[2],[3]
Deductions	0		0		0		0
Balance at End of Period(c)	129.2	[1]	28.3	[1]	93.6	[1]	180.2	[1]
Valuation Allowance Of Deferred Tax Assets [Member] | Argentina Distribution Business [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Charges or (Reductions) to Other Accounts(a)(b)			29.6
Allowance For Doubtful Accounts, Noncurrent [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at End of Period(c)	$8.50		$9.50		$11.30		$13.50
[1]	Allowance for doubtful accounts balance includes $9.5 million, $8.5 million, $11.3 million and $13.5 million of allowance on long-term receivables recorded in other long term assets for the year ended December 31, 2014, the seven months ended DecemberB 31, 2013 and the fiscal years ended MayB 31, 2013 and 2012, respectively.
[2]	For the year ended DecemberB 31, 2014, $29.6 million of the income tax valuation allowance reductions related to the disposition of Argentina.
[3]	The income tax valuation allowance adjustment was recorded to accumulated other comprehensive income and deferred taxes.