Condensed Consolidating Financial Statements (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Condensed, Consolidating Statement of Operations
Net sales	$ 953.6	$ 1,132.6
Cost of sales	537.8	689.8
Gross margin	415.8	442.8
Selling, general and administrative expenses	40.1	41.7
Other operating—net	18.2	(5.8)
Total other operating costs and expenses	58.3	35.9
Gain on sale of phosphate business	0	747.1
Equity in earnings of operating affiliates	9.7	15.8
Operating earnings	367.2	1,169.8
Interest expense	33.9	40.0
Interest income	(0.4)	(0.2)
Net (earnings) of wholly-owned subsidiaries	0
Other non-operating—net	0	(0.1)
Earnings before income taxes and equity in earnings of non-operating affiliates	333.7	1,130.1
Income tax (benefit) provision	112.7	413.2
Equity in earnings of non-operating affiliates—net of taxes	14.9	3.5
Net earnings	235.9	720.4
Less: Net earnings attributable to noncontrolling interest	5.3	11.9
Net earnings attributable to common stockholders	230.6	708.5
Reportable legal entities | Parent
Condensed, Consolidating Statement of Operations
Selling, general and administrative expenses	0.8	0.7
Other operating—net	0
Total other operating costs and expenses	0.8	0.7
Operating earnings	(0.8)	(0.7)
Net (earnings) of wholly-owned subsidiaries	(231.1)	(709.0)
Other non-operating—net	0
Earnings before income taxes and equity in earnings of non-operating affiliates	230.3	708.3
Income tax (benefit) provision	(0.3)	(0.2)
Net earnings	230.6	708.5
Net earnings attributable to common stockholders	230.6	708.5
Reportable legal entities | CFI
Condensed, Consolidating Statement of Operations
Net sales	81.3	372.0
Cost of sales	81.3	188.3
Gross margin	0	183.7
Selling, general and administrative expenses	0.3	1.4
Other operating—net	(5.2)	(0.3)
Total other operating costs and expenses	(4.9)	1.1
Gain on sale of phosphate business		761.5
Equity in earnings of operating affiliates		0
Operating earnings	4.9	944.1
Interest expense	64.9	49.4
Interest income	0	(0.1)
Net (earnings) of wholly-owned subsidiaries	(270.7)	(151.3)
Other non-operating—net	0.1	(0.1)
Earnings before income taxes and equity in earnings of non-operating affiliates	210.6	1,046.2
Income tax (benefit) provision	(20.5)	337.1
Equity in earnings of non-operating affiliates—net of taxes	0	(0.1)
Net earnings	231.1	709.0
Net earnings attributable to common stockholders	231.1	709.0
Reportable legal entities | Other Subsidiaries
Condensed, Consolidating Statement of Operations
Net sales	1,003.8	1,223.0
Cost of sales	588.0	963.9
Gross margin	415.8	259.1
Selling, general and administrative expenses	39.0	39.6
Other operating—net	23.4	(5.5)
Total other operating costs and expenses	62.4	34.1
Gain on sale of phosphate business		(14.4)
Equity in earnings of operating affiliates	9.7	15.8
Operating earnings	363.1	226.4
Interest expense	(31.0)	(9.3)
Interest income	(0.4)	(0.2)
Other non-operating—net	(0.1)	0
Earnings before income taxes and equity in earnings of non-operating affiliates	394.6	235.9
Income tax (benefit) provision	133.5	76.3
Equity in earnings of non-operating affiliates—net of taxes	14.9	3.6
Net earnings	276.0	163.2
Less: Net earnings attributable to noncontrolling interest	5.3	11.9
Net earnings attributable to common stockholders	270.7	151.3
Eliminations
Condensed, Consolidating Statement of Operations
Net sales	(131.5)	(462.4)
Cost of sales	(131.5)	(462.4)
Gross margin	0	0
Selling, general and administrative expenses		0
Total other operating costs and expenses		0
Operating earnings	0	0
Interest expense	0	(0.1)
Interest income	0	0.1
Net (earnings) of wholly-owned subsidiaries	501.8	860.3
Earnings before income taxes and equity in earnings of non-operating affiliates	(501.8)	(860.3)
Net earnings	(501.8)	(860.3)
Less: Net earnings attributable to noncontrolling interest	0	0
Net earnings attributable to common stockholders	$ (501.8)	$ (860.3)