Operating Segments (Details)
$ in Millions
1 Months Ended 3 Months Ended
Oct. 31, 2016
Business
Mar. 31, 2017
USD ($)
segment
Mar. 31, 2016
USD ($)
Dec. 31, 2016
USD ($)
Segment Reporting Information [Line Items]        
Number of reportable segments | segment   3    
Segment Reporting Information [Abstract]        
Sales   $ 387.8 $ 345.7  
Shipping and handling cost   93.7 89.4  
Operating earnings (loss)   41.4 74.3  
Depreciation, depletion and amortization   28.4 19.9  
Total assets (as of end of period)   2,323.3 1,651.9 $ 2,466.5
Operating Segments [Member] | Salt [Member]        
Segment Reporting Information [Abstract]        
Sales   274.8 292.1  
Shipping and handling cost   83.0 83.0  
Operating earnings (loss)   45.4 82.7  
Depreciation, depletion and amortization   12.9 10.7  
Total assets (as of end of period)   854.4 893.1  
Operating Segments [Member] | Plant Nutrition, North America [Member]        
Segment Reporting Information [Abstract]        
Sales   49.2 51.1  
Shipping and handling cost   6.7 6.4  
Operating earnings (loss)   7.6 5.3  
Depreciation, depletion and amortization   8.9 7.9  
Total assets (as of end of period)   583.4 704.8  
Operating Segments [Member] | Plant Nutrition South America [Member]        
Segment Reporting Information [Abstract]        
Sales   61.3 0.0  
Shipping and handling cost   4.0 0.0  
Operating earnings (loss)   1.8 0.0  
Depreciation, depletion and amortization   5.3 0.0  
Total assets (as of end of period)   834.7 0.0  
Corporate and Other [Member]        
Segment Reporting Information [Abstract]        
Sales   2.5 2.5  
Shipping and handling cost   0.0 0.0  
Operating earnings (loss)   (13.4) (13.7)  
Depreciation, depletion and amortization   1.3 1.3  
Total assets (as of end of period)   50.8 54.0  
Intersegment Sales [Member]        
Segment Reporting Information [Abstract]        
Sales   (0.9) (0.2)  
Intersegment Sales [Member] | Salt [Member]        
Segment Reporting Information [Abstract]        
Sales   0.0 0.0  
Intersegment Sales [Member] | Plant Nutrition, North America [Member]        
Segment Reporting Information [Abstract]        
Sales   0.9 0.2  
Intersegment Sales [Member] | Plant Nutrition South America [Member]        
Segment Reporting Information [Abstract]        
Sales   $ 0.0 $ 0.0  
Produquímica [Member]        
Segment Reporting Information [Line Items]        
Number of primary businesses | Business 2