Financing Arrangements - Short-term debt (Details) (USD $)	7 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2014	May 31, 2013	May 31, 2012
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		1,500,000,000.0
Line of credit facility, expiration date		Dec. 05, 2018
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		3.0
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%	0.125%	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		13,500,000.0
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