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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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The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities.

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The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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The net result for the period of deducting operating expenses from operating revenues.

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The cash outflow for purchases of and capital improvements on property, plant and equipment (capital expenditures), software, and other intangible assets.

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Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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OPERATING SEGMENTS (Segment Information) (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) Business segment	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments (in segments) \| segment									3
Sales	$ 500.3	$ 341.3	$ 245.2	$ 403.7	$ 486.5	$ 322.5	$ 246.7	$ 437.9	$ 1,490.5	$ 1,493.6	$ 1,364.4
Operating earnings (loss)									163.6	130.3	159.2
Depreciation, depletion and amortization									137.9	136.9	122.2
Total assets	2,443.2				2,367.9				2,443.2	2,367.9	2,571.0
Capital expenditures									$ 98.1	96.8	114.1
Plant Nutrition South America
Segment Reporting Information [Line Items]
Number of primary businesses (in businesses) \| Business									2
Reportable segments \| Salt
Segment Reporting Information [Line Items]
Sales									$ 889.5	858.1	769.2
Operating earnings (loss)									168.0	115.7	138.0
Depreciation, depletion and amortization									60.4	56.2	55.0
Total assets	1,056.3				948.9				1,056.3	948.9	1,030.6
Capital expenditures									65.9	58.7	65.8
Reportable segments \| Plant Nutrition North America
Segment Reporting Information [Line Items]
Sales									206.2	233.2	210.0
Operating earnings (loss)									22.5	25.3	27.7
Depreciation, depletion and amortization									44.6	48.6	36.9
Total assets	575.5				589.3				575.5	589.3	601.1
Capital expenditures									15.2	20.7	31.9
Reportable segments \| Plant Nutrition South America
Segment Reporting Information [Line Items]
Sales									385.1	391.8	375.0
Operating earnings (loss)									40.0	48.7	49.1
Depreciation, depletion and amortization									22.4	22.2	22.6
Total assets	715.3				709.9				715.3	709.9	808.0
Capital expenditures									10.5	10.1	11.3
Corporate & other
Segment Reporting Information [Line Items]
Sales									9.7	10.5	10.2
Operating earnings (loss)									(66.9)	(59.4)	(55.6)
Depreciation, depletion and amortization									10.5	9.9	7.7
Total assets	$ 96.1				$ 119.8				96.1	119.8	131.3
Capital expenditures									6.5	7.3	5.1
Intersegment sales
Segment Reporting Information [Line Items]
Sales									(9.1)	(9.0)	(6.5)
Intersegment sales \| Salt
Segment Reporting Information [Line Items]
Sales									0.0	0.0	0.0
Intersegment sales \| Plant Nutrition North America
Segment Reporting Information [Line Items]
Sales									6.4	5.6	6.5
Intersegment sales \| Plant Nutrition South America
Segment Reporting Information [Line Items]
Sales									2.7	3.4	0.0
Shipping and handling cost
Segment Reporting Information [Line Items]
Shipping and handling cost									312.5	320.0	267.5
Shipping and handling cost \| Reportable segments \| Salt
Segment Reporting Information [Line Items]
Shipping and handling cost									267.4	272.4	220.6
Shipping and handling cost \| Reportable segments \| Plant Nutrition North America
Segment Reporting Information [Line Items]
Shipping and handling cost									28.5	29.0	28.1
Shipping and handling cost \| Reportable segments \| Plant Nutrition South America
Segment Reporting Information [Line Items]
Shipping and handling cost									16.6	18.6	18.8
Shipping and handling cost \| Corporate & other
Segment Reporting Information [Line Items]
Shipping and handling cost									$ 0.0	$ 0.0	$ 0.0