Operating Segments (Details) $ in Millions | 3 Months Ended | 6 Months Ended | |
Jun. 30, 2019USD ($) | Jun. 30, 2018USD ($) | Jun. 30, 2019USD ($)Businesssegment | Jun. 30, 2018USD ($) | Dec. 31, 2018USD ($) |
Segment Reporting [Abstract] | | | | | |
Number of reportable segments | segment | | | 3 | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | $ 245.2 | $ 246.7 | $ 648.9 | $ 684.6 | |
Operating earnings (loss) | 4.1 | 2.8 | 37.3 | 29.4 | |
Depreciation, depletion and amortization | 33.9 | 35.3 | 68.9 | 69.6 | |
Total assets (as of end of period) | 2,320.9 | 2,274.3 | 2,320.9 | 2,274.3 | $ 2,367.9 |
United States | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 128.3 | 136.6 | 366.6 | 378.7 | |
Canada | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 27.9 | 28.3 | 115.3 | 119.1 | |
Brazil | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 79 | 68.5 | 134.7 | 134.1 | |
United Kingdom | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 5.7 | 9.9 | 23 | 46.6 | |
Other | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 4.3 | 3.4 | 9.3 | 6.1 | |
Shipping and handling cost | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Shipping and handling cost | 48 | 49.8 | 160.9 | 169.9 | |
Highway Deicing Salt | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 46.9 | 60.6 | 265.6 | 296 | |
Consumer & Industrial Salt | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 65.7 | 60.5 | 153.4 | 141 | |
SOP and Specialty Plant Nutrients | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 112.6 | 103.2 | 186.9 | 196.2 | |
Industrial Chemicals | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 21.3 | 23 | 43.9 | 49.8 | |
Operating Segments | Salt | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 112.6 | 121.1 | 419 | 437 | |
Operating earnings (loss) | 14.6 | 12.5 | 66.9 | 46.6 | |
Depreciation, depletion and amortization | 14.8 | 14.1 | 30.1 | 28.8 | |
Total assets (as of end of period) | 905.2 | 830.7 | 905.2 | 830.7 | |
Operating Segments | Salt | Shipping and handling cost | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Shipping and handling cost | 37.6 | 39.4 | 141.3 | 148.9 | |
Operating Segments | Salt | Highway Deicing Salt | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 46.9 | 60.6 | 265.6 | 296 | |
Operating Segments | Salt | Consumer & Industrial Salt | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 65.7 | 60.5 | 153.4 | 141 | |
Operating Segments | Salt | SOP and Specialty Plant Nutrients | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 0 | 0 | 0 | 0 | |
Operating Segments | Salt | Industrial Chemicals | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 0 | 0 | 0 | 0 | |
Operating Segments | Salt | Eliminations & Other | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 0 | 0 | 0 | 0 | |
Operating Segments | Plant Nutrition North America | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 48.1 | 51.8 | 85.3 | 104.7 | |
Operating earnings (loss) | 4.6 | 4.2 | 3 | 9.1 | |
Depreciation, depletion and amortization | 10.9 | 13 | 22.5 | 24.3 | |
Total assets (as of end of period) | 565.3 | 584.2 | 565.3 | 584.2 | |
Operating Segments | Plant Nutrition North America | Shipping and handling cost | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Shipping and handling cost | 6.5 | 6.2 | 12.5 | 12.6 | |
Operating Segments | Plant Nutrition North America | Highway Deicing Salt | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 0 | 0 | 0 | 0 | |
Operating Segments | Plant Nutrition North America | Consumer & Industrial Salt | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 0 | 0 | 0 | 0 | |
Operating Segments | Plant Nutrition North America | SOP and Specialty Plant Nutrients | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 50.7 | 54 | 88.4 | 107.1 | |
Operating Segments | Plant Nutrition North America | Industrial Chemicals | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 0 | 0 | 0 | 0 | |
Operating Segments | Plant Nutrition North America | Eliminations & Other | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | (2.6) | (2.2) | $ (3.1) | (2.4) | |
Operating Segments | Plant Nutrition South America | | | | | |
Segment Reporting Information [Line Items] | | | | | |
Number of primary businesses | Business | | | 2 | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 82.1 | 71.1 | $ 139.8 | 137.4 | |
Operating earnings (loss) | 1.7 | 0.7 | (0.9) | 1.5 | |
Depreciation, depletion and amortization | 5.4 | 5.6 | 11 | 11.5 | |
Total assets (as of end of period) | 731.5 | 726.2 | 731.5 | 726.2 | |
Operating Segments | Plant Nutrition South America | Shipping and handling cost | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Shipping and handling cost | 3.9 | 4.2 | 7.1 | 8.4 | |
Operating Segments | Plant Nutrition South America | Highway Deicing Salt | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 0 | 0 | 0 | 0 | |
Operating Segments | Plant Nutrition South America | Consumer & Industrial Salt | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 0 | 0 | 0 | 0 | |
Operating Segments | Plant Nutrition South America | SOP and Specialty Plant Nutrients | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 61.9 | 49.2 | 98.5 | 89.1 | |
Operating Segments | Plant Nutrition South America | Industrial Chemicals | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 21.3 | 23 | 43.9 | 49.8 | |
Operating Segments | Plant Nutrition South America | Eliminations & Other | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | (1.1) | (1.1) | (2.6) | (1.5) | |
Corporate & Other | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 2.4 | 2.7 | 4.8 | 5.5 | |
Operating earnings (loss) | (16.8) | (14.6) | (31.7) | (27.8) | |
Depreciation, depletion and amortization | 2.8 | 2.6 | 5.3 | 5 | |
Total assets (as of end of period) | 118.9 | 133.2 | 118.9 | 133.2 | |
Corporate & Other | Shipping and handling cost | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Shipping and handling cost | 0 | 0 | 0 | 0 | |
Corporate & Other | Highway Deicing Salt | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 0 | 0 | 0 | 0 | |
Corporate & Other | Consumer & Industrial Salt | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 0 | 0 | 0 | 0 | |
Corporate & Other | SOP and Specialty Plant Nutrients | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 0 | 0 | 0 | 0 | |
Corporate & Other | Industrial Chemicals | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 0 | 0 | 0 | 0 | |
Corporate & Other | Eliminations & Other | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 2.4 | 2.7 | 4.8 | 5.5 | |
Intersegment Eliminations | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | (3.7) | (3.3) | (5.7) | (3.9) | |
Intersegment Eliminations | Eliminations & Other | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | (1.3) | (0.6) | (0.9) | 1.6 | |
Intersegment Eliminations | Salt | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 0 | 0 | 0 | 0 | |
Intersegment Eliminations | Plant Nutrition North America | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | 2.6 | 2.2 | 3.1 | 2.4 | |
Intersegment Eliminations | Plant Nutrition South America | | | | | |
Segment Reporting Information [Abstract] | | | | | |
Sales | $ 1.1 | $ 1.1 | $ 2.6 | $ 1.5 | |