Business Segments (Details) (USD $) In Millions, unless otherwise specified	7 Months Ended	12 Months Ended
Dec. 31, 2013	Dec. 31, 2014	May 31, 2013	May 31, 2012
Segment Reporting Information [Line Items]
Net sales	$ 4,765.9us-gaap_SalesRevenueGoodsNet	$ 9,055.8us-gaap_SalesRevenueGoodsNet	$ 9,974.1us-gaap_SalesRevenueGoodsNet	$ 11,107.8us-gaap_SalesRevenueGoodsNet
Gross margin	828.3us-gaap_GrossProfit	1,926.6us-gaap_GrossProfit	2,760.2us-gaap_GrossProfit	3,085.0us-gaap_GrossProfit
Carlsbad restructuring expense	0	125.4	0	0
Operating earnings (loss)	416.9us-gaap_OperatingIncomeLoss	1,311.8us-gaap_OperatingIncomeLoss	2,209.6us-gaap_OperatingIncomeLoss	2,611.1us-gaap_OperatingIncomeLoss
Capital expenditures	800.0	929.1	1,588.3	1,639.3
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	19,554.0us-gaap_Assets	18,283.0us-gaap_Assets
Phosphates Segment [Member]
Segment Reporting Information [Line Items]
Net sales	3,438.2	6,194.0	6,494.6	7,839.2
Gross margin	445.0	1,071.2	1,162.2	1,466.9
Carlsbad restructuring expense		0
Operating earnings (loss)	199.7	766.7	848.1	1,179.1
Capital expenditures	298.7	439.0	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	9,945.1	11,392.2
Phosphates Segment [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	3,438.2	6,194.0	6,494.6	7,839.2
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	1,387.2	2,851.6	3,529.3	3,301.3
Gross margin	374.3	897.7	1,611.3	1,622.0
Carlsbad restructuring expense		125.4
Operating earnings (loss)	224.6	630.6	1,393.0	1,457.3
Capital expenditures	471.0	470.7	1,017.7	1,171.4
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	9,597.4	8,296.6
Potash Segment [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	1,323.9	2,839.9	3,469.1	3,263.1
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	9.0	(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	60.0
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	(1,405.8)
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	$ (63.3)	$ (11.7)	$ (60.2)	$ (38.2)

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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