Commitments and Contingencies	9 Months Ended
Sep. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies: The Company is involved in legal and administrative proceedings and claims of various types from normal Company activities. The Company is aware of an aboriginal land claim filed in 2003 by The Chippewas of Nawash and The Chippewas of Saugeen (the “Chippewas”) in the Ontario Superior Court against The Attorney General of Canada and Her Majesty The Queen In Right of Ontario. The Chippewas claim that a large part of the land under Lake Huron was never surrendered by treaty and thus seek a declaration that the Chippewas hold aboriginal title to those submerged lands. The land to which aboriginal title is claimed includes land under which the Company’s Goderich mine operates and has mining rights granted to it by the government of Ontario. The actions also seek damages for the value and loss of use of lands. The Company is not a party to the court actions. The Company understands that the Canadian and Ontario governments are defending the actions for aboriginal title on the basis, among other things, that common law does not recognize aboriginal title to the Great Lakes and other navigable waterways. Similar claims are pending with respect to other parts of the Great Lakes by other aboriginal claimants. The Company has been informed by the Ministry of The Attorney General of Ontario that “Canada takes the position that the common law does not recognize aboriginal title to the Great Lakes and its connecting waterways.” The Company is involved in proceedings alleging unfair labor practices at its Cote Blanche, Louisiana, mine. This matter arises out of a labor dispute between the Company and the United Steelworkers Union over the terms of a new contract for certain employees at the mine. These employees initiated a strike that began on April 7, 2010, and ended on June 15, 2010. In September 2012, the U.S. National Labor Relations Board issued a decision finding that the Company had committed unfair labor practices in connection with the labor dispute. Under the ruling, the Company is responsible for back pay to affected employees as a result of changes made in union work rules and past practices beginning April 1, 2010. Any requirement for the Company to pay back wages will be offset by any wages earned at other places of employment during this period. In the fourth quarter of 2013, this ruling was upheld by an appeals court and the Company recorded a reserve of approximately $5 million in its consolidated financial statements related to expected payments required to resolve the dispute. In the first quarter of 2015, additional information became available and the Company recorded an additional $2 million reserve for this matter in its consolidated financial statements. Both parties are currently negotiating in an effort to reach a settlement. If the Company is unable to come to terms with the union, the parties may agree to arbitration and any decisions reached in arbitration would be binding. The Company may need to record additional losses in its financial statements as a result of future developments. The Wisconsin Department of Agriculture, Trade and Consumer Protection (“DATCP”) has information indicating that agricultural chemicals are present within the subsurface area of the Kenosha, Wisconsin plant. The agricultural chemicals were used by previous owners and operators of the site. None of the identified chemicals have been used in association with Compass Minerals’ operations since it acquired the property in 2002. DATCP directed the Company to conduct further investigations into the possible presence of agricultural chemicals in soil and ground water at the Kenosha plant. The Company has completed such investigations of the soils and ground water and has provided the findings to DATCP. The Company is presently proceeding with select remediation activities to mitigate agricultural chemical impact to soils and ground water at the site. All investigations and mitigation activities to date, and any potential future remediation work, are being conducted under the Wisconsin Agricultural Chemical Cleanup Program (“ACCP”), which would provide for reimbursement of some of the costs. The Company may seek participation by, or cost reimbursement from, the parties responsible for the presence of any agricultural chemicals found in soil and ground water at this site if the Company does not receive an acknowledgment of no further action and is required to conduct further investigation or remedial work that may not be eligible for reimbursement under the ACCP. The Company does not believe that these actions will have a material adverse financial effect on the Company. Furthermore, while any litigation contains an element of uncertainty, management presently believes that the outcome of each such proceeding or claim, which is pending or known to be threatened, or all of them combined, will not have a material adverse effect on the Company’s results of operations, cash flows or financial position.

Commitments and Contingencies:

The Company is involved in legal and administrative proceedings and claims of various types from normal Company activities.

The Company is aware of an aboriginal land claim filed in 2003 by The Chippewas of Nawash and The Chippewas of Saugeen (the “Chippewas”) in the Ontario Superior Court against The Attorney General of Canada and Her Majesty The Queen In Right of Ontario. The Chippewas claim that a large part of the land under Lake Huron was never surrendered by treaty and thus seek a declaration that the Chippewas hold aboriginal title to those submerged lands. The land to which aboriginal title is claimed includes land under which the Company’s Goderich mine operates and has mining rights granted to it by the government of Ontario. The actions also seek damages for the value and loss of use of lands. The Company is not a party to the court actions. The Company understands that the Canadian and Ontario governments are defending the actions for aboriginal title on the basis, among other things, that common law does not recognize aboriginal title to the Great Lakes and other navigable waterways.

Similar claims are pending with respect to other parts of the Great Lakes by other aboriginal claimants. The Company has been informed by the Ministry of The Attorney General of Ontario that “Canada takes the position that the common law does not recognize aboriginal title to the Great Lakes and its connecting waterways.”

The Company is involved in proceedings alleging unfair labor practices at its Cote Blanche, Louisiana, mine. This matter arises out of a labor dispute between the Company and the United Steelworkers Union over the terms of a new contract for certain employees at the mine. These employees initiated a strike that began on April 7, 2010, and ended on June 15, 2010. In September 2012, the U.S. National Labor Relations Board issued a decision finding that the Company had committed unfair labor practices in connection with the labor dispute. Under the ruling, the Company is responsible for back pay to affected employees as a result of changes made in union work rules and past practices beginning April 1, 2010. Any requirement for the Company to pay back wages will be offset by any wages earned at other places of employment during this period. In the fourth quarter of 2013, this ruling was upheld by an appeals court and the Company recorded a reserve of approximately $5 million in its consolidated financial statements related to expected payments required to resolve the dispute.

In the first quarter of 2015, additional information became available and the Company recorded an additional $2 million reserve for this matter in its consolidated financial statements. Both parties are currently negotiating in an effort to reach a settlement. If the Company is unable to come to terms with the union, the parties may agree to arbitration and any decisions reached in arbitration would be binding. The Company may need to record additional losses in its financial statements as a result of future developments.

The Wisconsin Department of Agriculture, Trade and Consumer Protection (“DATCP”) has information indicating that agricultural chemicals are present within the subsurface area of the Kenosha, Wisconsin plant. The agricultural chemicals were used by previous owners and operators of the site. None of the identified chemicals have been used in association with Compass Minerals’ operations since it acquired the property in 2002. DATCP directed the Company to conduct further investigations into the possible presence of agricultural chemicals in soil and ground water at the Kenosha plant. The Company has completed such investigations of the soils and ground water and has provided the findings to DATCP. The Company is presently proceeding with select remediation activities to mitigate agricultural chemical impact to soils and ground water at the site. All investigations and mitigation activities to date, and any potential future remediation work, are being conducted under the Wisconsin Agricultural Chemical Cleanup Program (“ACCP”), which would provide for reimbursement of some of the costs. The Company may seek participation by, or cost reimbursement from, the parties responsible for the presence of any agricultural chemicals found in soil and ground water at this site if the Company does not receive an acknowledgment of no further action and is required to conduct further investigation or remedial work that may not be eligible for reimbursement under the ACCP.

The Company does not believe that these actions will have a material adverse financial effect on the Company. Furthermore, while any litigation contains an element of uncertainty, management presently believes that the outcome of each such proceeding or claim, which is pending or known to be threatened, or all of them combined, will not have a material adverse effect on the Company’s results of operations, cash flows or financial position.