Compass Minerals International (CMP) 10-Q 26 Jul 16 2016 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2016	Jul. 22, 2016
Document and Entity Information [Abstract]
Entity Registrant Name	COMPASS MINERALS INTERNATIONAL INC
Entity Central Index Key	1,227,654
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		33,786,067
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q2
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2016

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 92.7	$ 58.4
Receivables, less allowance for doubtful accounts of $1.6 in 2016 and $1.3 in 2015	71.9	147.8
Inventories	240.9	275.3
Other	30.9	30.8
Total current assets	436.4	512.3
Property, plant and equipment, net	890.5	800.7
Intangible assets, net	87	85.3
Goodwill	61.4	58.1
Investment in equity investee	124.1	116.4
Other	57.2	52
Total assets	1,656.6	1,624.8
Current liabilities:
Current portion of long-term debt	4	4.9
Accounts payable	54.5	80.7
Accrued expenses	47.7	48.9
Accrued salaries and wages	15.6	15.2
Income taxes payable	0	14.8
Accrued interest	6.3	6.3
Total current liabilities	128.1	170.8
Long-term debt, net of current portion	746.2	718
Deferred income taxes, net	71.2	71.3
Other noncurrent liabilities	26.7	25
Commitments and contingencies
Stockholders’ equity:
Common stock: $0.01 par value, 200,000,000 authorized shares; 35,367,264 issued shares	0.4	0.4
Additional paid-in capital	94.7	91.7
Treasury stock, at cost — 1,581,769 shares at June 30, 2016, and 1,665,731 shares at December 31, 2015	(3)	(3.2)
Retained earnings	667.9	659.1
Accumulated other comprehensive loss	(75.6)	(108.3)
Total stockholders’ equity	684.4	639.7
Total liabilities and stockholders’ equity	$ 1,656.6	$ 1,624.8

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Current assets:
Allowance for doubtful accounts	$ 1.6	$ 1.3
Stockholders’ equity:
Common Stock, par or stated value per share (in dollars per share)	$ 0.01	$ 0.01
Common Stock, shares authorized (in shares)	200,000,000	200,000,000
Common Stock, shares issued (in shares)	35,367,264	35,367,264
Treasury stock, shares (in shares)	1,581,769	1,665,731

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income Statement [Abstract]
Sales	$ 169.5	$ 183.7	$ 515.2	$ 576.7
Shipping and handling cost	37.1	40.8	126.5	142.7
Product cost	91.1	92.3	244.8	270.2
Gross profit	41.3	50.6	143.9	163.8
Selling, general and administrative expenses	25.8	26.6	54.1	55.1
Operating earnings	15.5	24	89.8	108.7
Other (income) expense:
Interest expense	5.6	5.3	11.4	10.7
Net loss from equity investee	1.7	0	1.3	0
Other, net	0.9	(1.2)	0.1	(4.7)
Earnings before income taxes	7.3	19.9	77	102.7
Income tax expense	1	6.7	21	28.9
Net earnings	$ 6.3	$ 13.2	$ 56	$ 73.8
Basic net earnings per common share (in dollars per share)	$ 0.18	$ 0.39	$ 1.65	$ 2.18
Diluted net earnings per common share (in dollars per share)	$ 0.18	$ 0.39	$ 1.65	$ 2.18
Weighted-average common shares outstanding (in thousands):
Basic (in shares)	33,784	33,682	33,766	33,654
Diluted (in shares)	33,787	33,701	33,769	33,675
Cash dividends per share (in dollars per share)	$ 0.695	$ 0.66	$ 1.39	$ 1.32

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
Net earnings	$ 6.3	$ 13.2	$ 56	$ 73.8
Other comprehensive income (loss):
Unrealized gain from change in pension obligations, net of tax of $(0.0) in both the three and six months ended June 30, 2016, and $(0.1) and $(0.2) in the three and six months ended June 30, 2015, respectively.	0.1	0.3	0.2	0.6
Unrealized gain on cash flow hedges, net of tax of $(0.7) and $(0.8) in the three and six months ended June 30, 2016, respectively, and $(0.3) and $(0.4) in the three and six months ended June 30, 2015, respectively.	1.2	0.5	1.4	0.5
Cumulative translation adjustment	(3.3)	11.2	31.1	(38.6)
Comprehensive income	$ 4.3	$ 25.2	$ 88.7	$ 36.3

CONSOLIDATED STATEMENTS OF COM6

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
Unrealized gain from change in pension obligations, tax	$ 0	$ (0.1)	$ 0	$ (0.2)
Unrealized gain on cash flow hedges, tax	$ (0.7)	$ (0.3)	$ (0.8)	$ (0.4)

CONSOLIDATED STATEMENT OF STOCK

CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY - USD ($) $ in Millions	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]
Beginning balance at Dec. 31, 2014						$ (15.5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	$ 36.3
Ending balance at Jun. 30, 2015						(53)
Beginning balance at Mar. 31, 2015						(65)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	25.2
Ending balance at Jun. 30, 2015						(53)
Beginning balance at Dec. 31, 2015	639.7	$ 0.4	$ 91.7	$ (3.2)	$ 659.1	(108.3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	88.7				56	32.7
Dividends on common stock	(47.1)		0.1		(47.2)
Shares issued for stock units	0		(0.1)	0.1
Income tax deficiency from equity awards	(0.2)		(0.2)
Stock options exercised	0.7		0.6	0.1
Stock-based compensation	2.6		2.6
Ending balance at Jun. 30, 2016	684.4	0.4	94.7	(3)	667.9	(75.6)
Beginning balance at Mar. 31, 2016						(73.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	4.3
Ending balance at Jun. 30, 2016	$ 684.4	$ 0.4	$ 94.7	$ (3)	$ 667.9	$ (75.6)

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Cash flows from operating activities:
Net earnings	$ 56	$ 73.8
Adjustments to reconcile net earnings to net cash flows provided by operating activities:
Depreciation, depletion and amortization	40.9	38.2
Finance fee amortization	0.6	0.6
Early extinguishment of debt	0.1	0
Stock-based compensation	2.6	3.3
Deferred income taxes	(4.1)	2.7
Net loss in equity investee	1.3	0
Other, net	(0.6)	2
Changes in operating assets and liabilities, net of acquisition:
Receivables	78.2	118.8
Inventories	35.8	(29.3)
Other assets	(0.2)	(5.9)
Accounts payable and accrued expenses	(60.5)	(92.5)
Other liabilities	(0.2)	0.5
Net cash provided by operating activities	149.9	112.2
Cash flows from investing activities:
Capital expenditures	(94.8)	(89.8)
Investment in equity method investee	(4.7)	0
Other, net	(1.5)	(0.5)
Net cash used in investing activities	(101)	(90.3)
Cash flows from financing activities:
Proceeds from the issuance of long-term debt	400	0
Proceeds from revolving credit facility borrowings	183.5	0
Principal payments on revolving credit facility borrowings	(80.5)	0
Principal payments on long-term debt	(473.4)	(1.9)
Dividends paid	(47.1)	(44.6)
Fees paid to refinance debt	(1.5)	0
Deferred financing costs	(3.5)	0
Proceeds received from stock option exercises	0.7	2.1
Excess tax benefit (deficiency) from equity compensation awards	(0.2)	0.1
Net cash used in financing activities	(22)	(44.3)
Effect of exchange rate changes on cash and cash equivalents	7.4	(10.7)
Net change in cash and cash equivalents	34.3	(33.1)
Cash and cash equivalents, beginning of the year	58.4	266.8
Cash and cash equivalents, end of period	92.7	233.7
Supplemental cash flow information:
Interest paid, net of amounts capitalized	10.7	10.9
Income taxes paid, net of refunds	$ 44.8	$ 73.4

Accounting Policies and Basis o

Accounting Policies and Basis of Presentation	6 Months Ended
	Jun. 30, 2016
Accounting Policies [Abstract]
Accounting Policies and Basis of Presentation	Accounting Policies and Basis of Presentation: Compass Minerals International, Inc., through its subsidiaries, is a producer and marketer of essential mineral products with manufacturing sites in North America and the United Kingdom (the “U.K.”). Except where otherwise noted, references to North America include only the continental United States (the “U.S.”) and Canada, and references to the U.K. include only England, Scotland and Wales. References to the “Company,” “Compass,” “Compass Minerals,” “we,” “us” and “our” refer to Compass Minerals International, Inc. (“CMI,” the parent holding company) and its consolidated subsidiaries. The Company’s principal products are salt, consisting of sodium chloride and magnesium chloride, and sulfate of potash (“SOP”), a specialty fertilizer the Company markets under the trade name Protassium+™. Additionally, the Company sells various premium micronutrient products under its Wolf Trax® brand. The Company provides highway deicing products to customers in North America and the U.K. and plant nutrients to growers and fertilizer distributors worldwide. The Company also produces and markets consumer deicing and water conditioning products, ingredients used in consumer and commercial food preparation, and other mineral-based products for consumer, agricultural and industrial applications. Compass Minerals also provides records management services to businesses located in the U.K. CMI is a holding company with no significant operations other than those of its wholly-owned subsidiaries. The consolidated financial statements include the accounts of CMI and its wholly-owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. The Company uses the equity method of accounting for equity securities when it has significant influence or when it has more than a minor ownership interest or more than a minor influence over the investee’s operations but does not have a controlling financial interest. The Company recognizes its share of the investee’s earnings or losses on a three -month lag as the investee’s financial information is not available on a timely basis. The accompanying unaudited consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. These unaudited consolidated financial statements should be read in conjunction with the consolidated financial statements of the Company for the year ended December 31, 2015 , as filed with the Securities and Exchange Commission in its Annual Report on Form 10-K. In the opinion of management, all adjustments, consisting of normal recurring accruals considered necessary for a fair presentation, have been included. The Company experiences a substantial amount of seasonality in its sales, primarily with respect to its deicing salt products. As a result, sales and operating income are generally higher in the first and fourth quarters and lower during the second and third quarters of each year. In particular, sales of highway and consumer deicing salt and magnesium chloride products vary based on the severity of the winter conditions in areas where the product is used. Following industry practice in North America and the U.K., the Company seeks to stockpile sufficient quantities of deicing salt throughout the second, third and fourth quarters to meet the estimated requirements for the upcoming winter season. Production of deicing salt can also vary based on the severity or mildness of the preceding winter season. Due to the seasonal nature of the deicing product lines, operating results for the interim periods are not necessarily indicative of the results that may be expected for the full year. Reclassifications Certain prior year amounts have been reclassified from other noncurrent assets to long-term debt, net of current portion, to conform to the current year presentation as required by the new accounting standard on debt issuance costs (see Note 7). Recent Accounting Pronouncements In June 2016, the Financial Accounting Standards Board (the “FASB”) issued guidance for estimating credit losses on certain types of financial instruments, including trade receivables, by introducing an approach based on expected losses. The expected loss approach will require entities to incorporate considerations of historical information, current information and reasonable and supportable forecasts. The guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The guidance requires a modified retrospective transition method and early adoption is permitted. The Company is currently evaluating the impact of the adoption of this guidance on its consolidated financial statements. In March 2016, the FASB issued guidance to simplify several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. The guidance is effective for fiscal years ending after December 15, 2016, and early adoption is permitted. The Company is currently evaluating the impact of the adoption of this guidance on its consolidated financial statements. In February 2016, the FASB issued guidance which requires lessees to recognize on their balance sheet a right-of-use asset which represents a lessee’s right to use the underlying asset. Under this guidance, an entity must also recognize a lease liability which represents a lessee’s obligation to make lease payments for the right to use the asset. In addition, the standard requires expanded qualitative and quantitative disclosures. The guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, and requires a modified retrospective transition method. The Company is currently evaluating the impact of the adoption of this guidance on its consolidated financial statements. In July 2015, the FASB issued guidance that requires entities to measure inventory within the scope of the standard at the lower of cost or net realizable value. “Net realizable value” is defined as the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation. The guidance is effective for fiscal years, and interim periods within those years, beginning after December 15, 2016. Early adoption is permitted. The Company does not plan to early adopt, and the Company does not expect that this guidance will have a material impact on its consolidated financial statements. In August 2014, the FASB issued guidance which requires management to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and to provide disclosure in the footnotes under certain circumstances. This guidance is effective for fiscal years ending after December 15, 2016, and interim periods within annual periods beginning after December 15, 2016, with early adoption permitted. The Company does not plan to early adopt, and the Company does not expect that this guidance will have a material impact on its consolidated financial statements. In May 2014, the FASB issued guidance to provide a single, comprehensive revenue recognition model for all contracts with customers. The new revenue recognition model supersedes existing revenue recognition guidance and requires revenue recognition to depict the transfer of promised goods or services to customers in an amount that reflects the consideration an entity expects to receive in exchange for those goods or services. This guidance is effective for fiscal years and interim periods with those years beginning after December 15, 2017, and early adoption is permitted. The guidance permits the use of either a full or modified retrospective or cumulative effect transition method. The Company is currently evaluating the impact of this guidance on its consolidated financial statements.

Equity Investment

Equity Investment	6 Months Ended
	Jun. 30, 2016
Equity Method Investments and Joint Ventures [Abstract]
Equity Investment	Equity Investment: In December 2015, the Company entered into a subscription agreement with Produquímica Indústria e Comércio S.A.(“Produquímica”), a Brazilian corporation, and a sale and purchase agreement with certain shareholders of Produquímica. Pursuant to these agreements, the Company acquired, in the aggregate, 35% of the issued and outstanding capital stock of Produquímica for an aggregate purchase price of $452.4 million Brazilian reals, or $114.1 million U.S. dollars at closing. Of the 35% capital stock, 6% consisted of common shares at closing, and the remaining 29% consisted of preferred shares that converted to common shares upon the settlement of certain post-closing adjustments, including additional consideration paid by the Company based upon Produquímica’s 2015 financial performance. The additional consideration of $4.7 million U.S. dollars was paid in the second quarter of 2016 and was recorded as an increase in investment in equity investee in the Company’s consolidated financial statements. The subscription agreement also contains a put option, allowing the majority shareholders to notify the Company of their intent to sell the remaining equity interests in Produquímica to the Company during October 2016, 2017 or 2018, and a call option, allowing the Company to notify the Produquímica shareholders of its intent to purchase the remaining equity interests in Produquímica during October 2018, in each case at the price and on other terms and conditions set forth in the subscription agreement. The exercise price of either the put or call option will be based on the adjusted EBITDA of Produquímica for the fiscal year in which the option is exercised, and the transaction is expected to close after the applicable fiscal year end, subject to regulatory approval. In connection with this transaction, the Company entered into a new U.S. dollar-denominated $100.0 million term loan in the fourth quarter of 2015 with certain existing lenders to fund the acquisition of the 35% equity stake in Produquímica. The term loan was refinanced in the second quarter of 2016 (see Note 7). In connection with the acquisition, the Company completed a purchase price allocation for the Company’s investment in Produquímica. As of the acquisition date, the cost basis of the Company’s equity interest in Produquímica exceeded the Company’s proportional interest in the underlying net assets of Produquímica. This basis difference of approximately $115 million represents the Company’s share of the amount by which the fair market value of Produquímica’s net identifiable assets exceeded their book value and equity method goodwill. The portion of the basis difference related to property, plant and equipment and intangible assets is being amortized based on the remaining estimated useful lives of the various underlying net assets, as appropriate. The portion of the basis difference related to finished goods inventory is being expensed as the inventory is sold. The additional expense associated with these basis differences is included as a component of the Company’s share of the equity investee’s earnings or loss. These basis differences were based on preliminary calculations and valuations, and the estimates and assumptions are subject to change as additional information is obtained. The Company recognizes its share of earnings or losses from Produquímica on a three-month lag. The Company has recognized losses of $1.7 million and $1.3 million related to its share of earnings for the three and six months ended June 30, 2016 , respectively, in its consolidated statements of operations.

Inventories

Inventories	6 Months Ended
	Jun. 30, 2016
Inventory Disclosure [Abstract]
Inventories	Inventories: Inventories consist of the following (in millions): June 30, December 31, Finished goods $ 186.0 $ 223.1 Raw materials and supplies 54.9 52.2 Total inventories $ 240.9 $ 275.3

Property, Plant and Equipment,

Property, Plant and Equipment, Net	6 Months Ended
	Jun. 30, 2016
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment, Net	Property, Plant and Equipment, Net: Property, plant and equipment, net, consists of the following (in millions): June 30, December 31, Land, buildings and structures and leasehold improvements $ 362.2 $ 347.3 Machinery and equipment 741.4 701.5 Office furniture and equipment 24.9 25.4 Mineral interests 171.2 169.6 Construction in progress 261.2 191.5 1,560.9 1,435.3 Less accumulated depreciation and depletion (670.4 ) (634.6 ) Property, plant and equipment, net $ 890.5 $ 800.7

Goodwill and Intangible Assets,

Goodwill and Intangible Assets, Net	6 Months Ended
	Jun. 30, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets, Net	Goodwill and Intangible Assets, Net: The estimated lives of the Company’s intangible assets are as follows: Intangible asset Estimated Lives Supply agreement 50 years SOP production rights 25 years Patents 10-20 years Developed technology 5 years Lease rights 25 years Customer and distributor relationships 10 years Trademarks 10 years Noncompete agreements 5 years Trade names Indefinite Water rights Indefinite None of the finite-lived intangible assets have a residual value. Aggregate amortization expense was $1.1 million and $1.2 million in the second quarters of 2016 and 2015 , respectively, and $2.1 million and $2.3 million in the first six months of 2016 and 2015 , respectively. The Company had goodwill of $61.4 million and $58.1 million as of June 30, 2016 , and December 31, 2015 , respectively, in its consolidated balance sheets. $55.3 million and $51.7 million of the amounts recorded for goodwill as of June 30, 2016 , and December 31, 2015 , respectively, were recorded in the Company’s plant nutrition segment, and the remaining amounts in both periods were immaterial and recorded in the Company’s salt segment and corporate and other. The change in goodwill between December 31, 2015 , and June 30, 2016, was due to the impact from translating foreign-denominated amounts to U.S. dollars.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2016
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes: The Company’s effective income tax rate differs from the U.S. statutory federal income tax rate primarily due to U.S. statutory depletion, state income taxes (net of federal tax benefit), foreign income tax rate differentials, foreign mining taxes, domestic manufacturing deductions and interest expense recognition differences for book and tax purposes. The Company’s effective rate is impacted by permanent tax deductions which have a less favorable impact as pretax income increases. The Company had $5.1 million and $3.6 million as of June 30, 2016 , and December 31, 2015 , respectively, of gross foreign federal net operating loss (“NOL”) carryforwards that have no expiration date. In addition, the Company had $11.4 million and $6.4 million as of June 30, 2016 , and December 31, 2015 , respectively, of gross foreign federal NOL carryforwards which expire beginning in 2033 and $1.4 million and $0.8 million as of June 30, 2016 , and December 31, 2015 , respectively, of tax-effected state NOL carryforwards which expire beginning in 2033 . Canadian provincial tax authorities have challenged tax positions claimed by one of the Company’s Canadian subsidiaries and have issued tax reassessments for years 2002 - 2011 . The reassessments are a result of ongoing audits and total $94.4 million , including interest through June 30, 2016 . The Company disputes these reassessments and plans to continue to work with the appropriate authorities in Canada to resolve the dispute. There is a reasonable possibility that the ultimate resolution of this dispute, and any related disputes for other open tax years, may be materially higher or lower than the amounts the Company has reserved for such disputes. In connection with this dispute, local regulations require the Company to post security with the tax authority until the dispute is resolved. The Company has posted collateral in the form of a $61.2 million performance bond, has paid $29.2 million (most of which is recorded in other assets in its consolidated balance sheets) and the remaining balance (which is currently $4.0 million ) will be addressed later this year, which is necessary to proceed with future appeals or litigation. In addition, Canadian federal and provincial taxing authorities have reassessed the Company for years 2004 - 2006 , which have been previously settled by agreement among the Company, the Canadian federal taxing authority and the U.S. federal taxing authority. The Company has fully complied with the agreement since entering into it, and it believes this action is highly unusual. The Company is seeking to enforce the agreement which provided the basis upon which the returns were previously filed and settled. The total amount of the reassessments, including penalties and interest through June 30, 2016 , related to this matter is $95.6 million . The Company has posted collateral in the form of a $20.6 million performance bond and a $37.2 million bank letter guarantee, which is necessary to proceed with future appeals or litigation. A trial commenced in the Tax Court of Canada in July 2016 with respect to the Canadian federal tax issues for these matters, and the outcome of the trial is pending. The Company received Canadian income tax reassessments for years 2007 - 2008 . The total amount of the reassessments, including penalties and interest through June 30, 2016 , related to this matter is $33.8 million . The Company does not agree with these adjustments and is receiving assistance from the tax jurisdictions for relief from the impact of double taxation as available in the tax treaty between the U.S. and Canada. The Company has filed protective Notices of Objection and has agreed to post collateral in the form of a $9.2 million performance bond and a $10.1 million bank letter guarantee, which is necessary to proceed with future appeals or litigation. Although the outcome of examinations by taxing authorities is uncertain, the Company believes it has adequately reserved for this matter. The Company will be required by local regulations to provide security for additional interest on the above disputed amounts and for any future reassessments issued by these Canadian tax authorities in the form of cash, letters of credit, performance bonds, asset liens or other arrangements agreeable with the tax authorities until the dispute is resolved. The Company expects that the ultimate outcome of these matters will not have a material impact on its results of operations, cash flows or financial condition. However, the Company can provide no assurance as to the ultimate outcome of these matters and the impact could be material if they are not resolved in the Company’s favor. As of June 30, 2016 , the amount reserved related to these reassessments was immaterial to the Company’s consolidated financial statements. Additionally, the Company has other uncertain tax positions as well as assessments and disputed positions with taxing authorities in its various jurisdictions.

Long-term Debt

Long-term Debt	6 Months Ended
	Jun. 30, 2016
Debt Disclosure [Abstract]
Long-term Debt	Long-term Debt: Long-term debt consists of the following (in millions): June 30, December 31, Term Loan due July 2021 $ 396.0 $ — Term Loan due May 2017 — 471.9 Revolving Credit Facility due August 2017 — 4.5 Revolving Credit Facility due July 2021 107.5 — 4.875% Senior Notes due July 2024 246.7 246.5 750.2 722.9 Less current portion (4.0 ) (4.9 ) Long-term debt $ 746.2 $ 718.0 In April 2016, the Company refinanced its existing $471 million term loans and $125 million revolving credit facility with a new $400 million senior secured term loan and a $300 million senior secured revolving credit facility, which both mature July 1, 2021. The new term loan and revolving credit facility bear interest at LIBOR plus 1.5% based on the Company’s current leverage ratio and credit rating. In connection with the refinancing, the Company incurred $6.1 million of refinancing fees ( $1.5 million was recorded as an expense and $4.6 million was capitalized as deferred financing costs) and wrote-off $0.1 million of existing deferred financing costs related to the previous term loans and revolving credit facility. In the first quarter of 2016, the Company adopted guidance which requires debt issuance costs to be presented as a reduction to the carrying value of the related debt rather than as a deferred charge. In connection with this adoption, the Company reclassified $3.3 million and $3.5 million of debt issuance costs related to its 4.875% senior notes due July 2024 and $3.0 million and $0.6 million of debt costs related to its term loans in its consolidated balance sheets as of June 30, 2016 , and December 31, 2015 , respectively. As of June 30, 2016, the term loan and revolving credit facility were secured by substantially all existing and future U.S. assets, the Goderich mine in Ontario, Canada and capital stock of certain subsidiaries.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies: 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 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 $5.0 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 $2.0 million reserve for this matter in its consolidated financial statements. The Company is also recording interest on the amount reserved at approximately 4% per year. 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. Currently, the reserves that the Company has recorded for this matter are at the minimum of its estimated range of potential losses, and 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 may be present in soil and ground water at the Company’s 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 the Company’s 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 these investigations of the soil 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 soil and ground water at the site. All investigations and mitigation activities to date are being conducted, and any potential future remediation work may be conducted, under the Wisconsin Agricultural Chemical Cleanup Program (the “ACCP”), which would provide for reimbursement of some of the costs. The Company also 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 from DACTP and is required to conduct further investigation or remedial work that may not be eligible for reimbursement under the ACCP. In addition, from time to time, the Company is involved in various routine legal proceedings arising from the ordinary course of the Company’s business. These primarily involve commercial claims, product liability claims, personal injury claims and workers’ compensation claims. Management cannot predict the outcome of legal proceedings and claims with certainty. Nevertheless, management believes that the outcome of legal proceedings and claims, which are pending or known to be threatened, even if determined adversely, will not, either individually or in the aggregate, have a material adverse effect on the Company’s results of operations, cash flows or financial condition.

Operating Segments

Operating Segments	6 Months Ended
	Jun. 30, 2016
Segment Reporting [Abstract]
Operating Segments	Operating Segments: Segment information is as follows (in millions): Three Months Ended June 30, 2016 Salt Plant Nutrition (a) Corporate and Other (b) Total Sales to external customers $ 119.1 $ 47.8 $ 2.6 $ 169.5 Intersegment sales — 1.9 (1.9 ) — Shipping and handling cost 31.4 5.7 — 37.1 Operating earnings (loss) 23.3 4.7 (12.5 ) 15.5 Depreciation, depletion and amortization 11.3 8.4 1.3 21.0 Total assets (as of end of period) 899.1 702.7 54.8 1,656.6 Three Months Ended June 30, 2015 Salt Plant Nutrition (a) Corporate and Other (b) Total Sales to external customers $ 116.3 $ 64.1 $ 3.3 $ 183.7 Intersegment sales 0.1 2.8 (2.9 ) — Shipping and handling cost 35.1 5.7 — 40.8 Operating earnings (loss) 21.1 16.8 (13.9 ) 24.0 Depreciation, depletion and amortization 10.9 7.1 1.1 19.1 Total assets (as of end of period) 905.6 563.0 61.7 1,530.3 Six Months Ended June 30, 2016 Salt Plant Nutrition (a) Corporate and Other (b) Total Sales to external customers $ 411.2 $ 98.9 $ 5.1 $ 515.2 Intersegment sales — 2.1 (2.1 ) — Shipping and handling cost 114.4 12.1 — 126.5 Operating earnings (loss) 106.0 10.0 (26.2 ) 89.8 Depreciation, depletion and amortization 22.0 16.3 2.6 40.9 Six Months Ended June 30, 2015 Salt Plant Nutrition (a) Corporate and Other (b) Total Sales to external customers $ 433.0 $ 137.7 $ 6.0 $ 576.7 Intersegment sales 0.1 3.5 (3.6 ) — Shipping and handling cost 129.6 13.1 — 142.7 Operating earnings (loss) 98.1 37.6 (27.0 ) 108.7 Depreciation, depletion and amortization 21.8 14.1 2.3 38.2 (a) Plant nutrition segment assets include the investment in Produquímica. (b) Corporate and other includes corporate entities, records management operations and other incidental operations and eliminations. Operating earnings (loss) for corporate and other includes indirect corporate overhead, including costs for general corporate governance and oversight, as well as costs for the human resources, information technology, legal and finance functions.

Stockholders' Equity and Equity

Stockholders' Equity and Equity Instruments	6 Months Ended
	Jun. 30, 2016
Equity [Abstract]
Stockholders' Equity and Equity Instruments	Stockholders’ Equity and Equity Instruments: In May 2015, the Company’s shareholders approved the 2015 Incentive Award Plan, which authorizes the issuance of 3,000,000 shares. Since the date the 2015 Incentive Award Plan was approved, the Company ceased issuing equity awards under the 2005 Incentive Award Plan. In 2016, the Company elected to move its grant date for annual grants of equity awards from March to April. For outstanding awards, the Company’s closing stock price on the grant date was used to set the exercise price for options and the fair value of restricted stock units (“RSUs”). In the first six months of 2016, the Company granted 157,887 options, 25,565 RSUs and 42,902 performance stock units (“PSUs”) to certain employees under its 2015 Incentive Award Plan. None of the granted equity awards have voting rights. Options Options granted in 2016 vest ratably on each anniversary date over a four -year service period. Unexercised options expire after seven years. Options do not have dividend rights. To estimate the fair value of options on the grant date, the Company uses the Black-Scholes option valuation model . Award recipients are grouped according to expected exercise behavior. Unless better information is available to estimate the expected term of the options, the estimate is based on historical exercise experience. The risk-free rate, using U.S. Treasury yield curves in effect at the time of grant, is selected based on the expected term of each group. The Company’s historical stock price is used to estimate expected volatility. The inputs used to calculate fair value for options granted in 2016 are included in the table below. Fair value of options granted $10.17 Exercise price $70.58 Expected term (years) 4.5 Expected volatility 24.4% Dividend yield 3.3% Risk-free rate of return 1.2% RSUs RSUs granted in 2016 vest on the third anniversary following the grant date and are earned after a performance hurdle tied to the Company’s 2016 financial performance has been satisfied. Holders of RSUs are entitled to receive non-forfeitable dividends or other distributions equal to those declared on the Company’s common stock for RSUs that are earned. PSUs PSUs granted in 2016 have a three -year performance period that begins on the grant date and vest on the third anniversary following the grant date. PSUs represent a target number of shares of Company common stock that may be earned before adjustment based upon the attainment of certain performance conditions. Holders of PSUs are entitled to receive non-forfeitable dividends or other distributions equal to those declared on the Company’s common stock for PSUs that are earned. The Company granted two types of PSUs in 2016, total shareholder return PSUs (“TSR PSUs”) and return on invested capital PSUs (“ROIC PSUs”). The actual number of shares of common stock that may be earned with respect to TSR PSUs is calculated by comparing the Company’s total shareholder return to the total shareholder return for each company comprising the Russell 3000 Index over the three -year performance period and may range from 0% to 150% of the target number of shares based upon the attainment of these performance conditions. The actual number of shares of common stock that may be earned with respect to ROIC PSUs is calculated by averaging the Company’s annual return on invested capital for each year in the three -year performance period and may range from 0% to 200% of the target number of shares based upon the attainment of these performance conditions. To estimate the fair value of the TSR PSUs on the grant date, the Company uses a Monte-Carlo simulation model, which simulates future stock prices of the Company as well as the companies comprising the Russell 3000 Index. This model uses historical stock prices to estimate expected volatility and the Company’s correlation to the Russell 3000 Index. The risk-free rate was determined using the same methodology as the option valuations as discussed above. The Company’s closing stock price on the grant date was used to estimate the fair value of the ROIC PSUs. The Company will adjust the expense of the ROIC PSUs based upon its estimate of the number of shares that will ultimately vest at each interim date during the three -year vesting period. During the six months ended June 30, 2016 , the Company reissued the following number of shares from treasury stock: 11,377 shares related to the exercise of stock options, 51,324 shares related to the release of RSUs which vested, 10,258 shares related to the release of PSUs which vested and 11,003 shares related to stock payments. The Company recognized a tax deficiency of $0.2 million from its equity compensation awards as a decrease to additional paid-in capital during the first six months of 2016 . During the first six months of 2016 and 2015 , the Company recorded $2.6 million and $3.3 million , respectively, of compensation expense pursuant to its stock-based compensation plans. No amounts have been capitalized. The following table summarizes stock-based compensation activity during the six months ended June 30, 2016 . Stock Options RSUs PSUs (a) Number Weighted-average exercise price Number Weighted-average fair value Number Weighted-average fair value Outstanding at December 31, 2015 353,087 $ 83.94 91,008 $ 80.65 77,365 $ 96.63 Granted 157,887 70.48 25,565 70.48 42,902 73.77 Exercised (b) (11,377 ) 62.52 — — — — Released from restriction (b) — — (51,324 ) 75.18 (10,258 ) 78.49 Cancelled/expired (17,033 ) 86.53 (2,265 ) 89.70 (9,219 ) 88.47 Outstanding at June 30, 2016 482,564 $ 79.95 62,984 $ 80.66 100,790 $ 89.50 (a) Until they vest, PSUs are included in the table at the target level at their grant date and at that level represent one share of common stock per PSU. The final performance period for the 2013 PSU grant was completed in 2015. The Company cancelled 5,263 PSUs in the first quarter of 2016 related to the 2013 PSU grant. (b) Common stock issued for exercised options and for vested and earned RSUs and PSUs was issued from treasury stock. Other Comprehensive Income (Loss) The Company’s comprehensive income (loss) is comprised of net earnings, net amortization of the unrealized loss of the pension obligation, the change in the unrealized gain (loss) on natural gas cash flow hedges and foreign currency translation adjustments. The components of and changes in accumulated other comprehensive income (loss) (“AOCI”) as of and for the three and six months ended June 30, 2016 , and 2015 , are as follows (in millions): Three Months Ended June 30, 2016 (a) Gains and (Losses) on Cash Flow Hedges Defined Benefit Pension Foreign Currency Total Beginning balance $ (1.4 ) $ (3.7 ) $ (68.5 ) $ (73.6 ) Other comprehensive income (loss) before reclassifications (b) 0.7 — (3.3 ) (2.6 ) Amounts reclassified from accumulated other comprehensive loss 0.5 0.1 — 0.6 Net current period other comprehensive income (loss) 1.2 0.1 (3.3 ) (2.0 ) Ending balance $ (0.2 ) $ (3.6 ) $ (71.8 ) $ (75.6 ) Three Months Ended June 30, 2015 (a) Gains and (Losses) on Cash Flow Hedges Defined Benefit Pension Foreign Currency Total Beginning balance $ (2.0 ) $ (8.7 ) $ (54.3 ) $ (65.0 ) Other comprehensive income (loss) before reclassifications (b) 0.1 — 11.2 11.3 Amounts reclassified from accumulated other comprehensive loss 0.4 0.3 — 0.7 Net current period other comprehensive income (loss) 0.5 0.3 11.2 12.0 Ending balance $ (1.5 ) $ (8.4 ) $ (43.1 ) $ (53.0 ) Six Months Ended June 30, 2016 (a) Gains and (Losses) on Cash Flow Hedges Defined Benefit Pension Foreign Currency Total Beginning balance $ (1.6 ) $ (3.8 ) $ (102.9 ) $ (108.3 ) Other comprehensive income (loss) before reclassifications (b) 0.2 — 31.1 31.3 Amounts reclassified from accumulated other comprehensive loss 1.2 0.2 — 1.4 Net current period other comprehensive income (loss) 1.4 0.2 31.1 32.7 Ending balance $ (0.2 ) $ (3.6 ) $ (71.8 ) $ (75.6 ) Six Months Ended June 30, 2015 (a) Gains and (Losses) on Cash Flow Hedges Defined Benefit Pension Foreign Currency Total Beginning balance $ (2.0 ) $ (9.0 ) $ (4.5 ) $ (15.5 ) Other comprehensive income (loss) before reclassifications (b) (0.6 ) — (38.6 ) (39.2 ) Amounts reclassified from accumulated other comprehensive loss 1.1 0.6 — 1.7 Net current period other comprehensive income (loss) 0.5 0.6 (38.6 ) (37.5 ) Ending balance $ (1.5 ) $ (8.4 ) $ (43.1 ) $ (53.0 ) (a) With the exception of the cumulative foreign currency translation adjustment, for which no tax effect is recorded, the changes in the components of accumulated other comprehensive gain (loss) presented in the tables above are reflected net of applicable income taxes. (b) The Company recorded foreign exchange (gains) losses of $(4.9) million and $(26.7) million in the three and six months ended June 30, 2016 , respectively, and $(2.7) million and $14.6 million in the three and six months ended June 30, 2015 , respectively, in accumulated other comprehensive income (loss) related to intercompany notes which were deemed to be of long-term investment nature. The amounts reclassified from AOCI to (income) expense for the three and six months ended June 30, 2016 , and 2015 , are shown below (in millions): Amount Reclassified from AOCI Three Months Ended Six Months Ended Line Item Impacted in the Consolidated Statement of Operations Gains and (losses) on cash flow hedges: Natural gas instruments $ 0.8 $ 1.9 Product cost (0.3 ) (0.7 ) Income tax expense (benefit) Reclassifications, net of income taxes 0.5 1.2 Amortization of defined benefit pension: Amortization of loss $ 0.1 $ 0.2 Product cost — — Income tax expense (benefit) Reclassifications, net of income taxes 0.1 0.2 Total reclassifications, net of income taxes $ 0.6 $ 1.4 Amount Reclassified from AOCI Three Months Ended Six Months Ended Line Item Impacted in the Consolidated Statement of Operations Gains and (losses) on cash flow hedges: Natural gas instruments $ 0.6 $ 1.7 Product cost (0.2 ) (0.6 ) Income tax expense (benefit) Reclassifications, net of income taxes 0.4 1.1 Amortization of defined benefit pension: Amortization of loss $ 0.3 $ 0.7 Product cost — (0.1 ) Income tax expense (benefit) Reclassifications, net of income taxes 0.3 0.6 Total reclassifications, net of income taxes $ 0.7 $ 1.7

Derivative Financial Instrument

Derivative Financial Instruments	6 Months Ended
	Jun. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	Derivative Financial Instruments: The Company is subject to various types of market risks, including interest rate risk, foreign currency exchange rate transaction and translation risk and commodity pricing risk. Management may take actions to mitigate the exposure to these types of risks, including entering into forward purchase contracts and other financial instruments. Currently, the Company manages a portion of its commodity pricing risk by using derivative instruments. The Company does not seek to engage in trading activities or take speculative positions with any financial instrument arrangements. The Company has entered into natural gas derivative instruments with counterparties it views as creditworthy. However, management does attempt to mitigate its counterparty credit risk exposures by, among other things, entering into master netting agreements with these counterparties. Cash Flow Hedges As of June 30, 2016 , the Company has entered into natural gas derivative instruments. The Company records derivative financial instruments as either assets or liabilities at fair value in the consolidated balance sheets. Derivatives qualify for treatment as hedges when there is a high correlation between the change in fair value of the derivative instrument and the related change in value of the underlying hedged item. Depending on the exposure being hedged, the Company must designate the hedging instrument as a fair value hedge, a cash flow hedge or a net investment in foreign operations hedge. All derivative instruments held by the Company as of June 30, 2016 , and December 31, 2015 , qualified as cash flow hedges. For these qualifying hedges, the effective portion of the change in fair value is recognized through earnings when the underlying transaction being hedged affects earnings, allowing a derivative’s gains and losses to offset related results from the hedged item in the statements of operations (see Note 10). For derivative instruments that are not accounted for as hedges, or for the ineffective portions of qualifying hedges, the change in fair value is recorded through earnings in the period of change. The Company formally documents, designates and assesses the effectiveness of transactions that receive hedge accounting treatment initially and on an ongoing basis. Any ineffectiveness related to these hedges was not material for any of the periods presented. Natural gas is consumed at several of the Company’s production facilities, and a change in natural gas prices impacts the Company’s operating margin. As of June 30, 2016 , the Company had entered into natural gas derivative instruments to hedge a portion of its natural gas purchase requirements through December 2017 . The Company’s objective is to reduce the earnings and cash flow impacts of changes in market prices of natural gas by fixing the purchase price of up to 90% of its forecasted natural gas usage. It is the Company’s policy to consider hedging portions of its natural gas usage up to 36 months in advance of the forecasted purchase. As of June 30, 2016 , and December 31, 2015 , the Company had agreements in place to hedge forecasted natural gas purchases of 2.6 million and 2.8 million MMBtus, respectively. As of June 30, 2016 , the Company expects to reclassify from accumulated other comprehensive loss to earnings during the next twelve months $0.4 million of net losses on derivative instruments related to its natural gas hedges. The following tables present the fair value of the Company’s hedged items as of June 30, 2016 , and December 31, 2015 (in millions): Asset Derivatives Liability Derivatives Derivatives designated as hedging instruments (a) Balance Sheet Location June 30, Balance Sheet Location June 30, Commodity contracts Other current assets $ 0.5 Accrued expenses $ 0.8 Commodity contracts Other assets 0.1 Other noncurrent liabilities 0.1 Total derivatives designated as hedging instruments $ 0.6 $ 0.9 (a) As of June 30, 2016 , the Company had commodity hedge agreements with two counterparties. Amounts recorded as liabilities for the Company’s commodity contracts were payable to one counterparty, and amounts recorded as assets were due from one counterparty. The Company has master netting agreements with its counterparties and accordingly has netted in its consolidated balance sheets $0.4 million of contracts that were in receivable positions against its contracts in payable positions. Asset Derivatives Liability Derivatives Derivatives designated as hedging instruments (a) Balance Sheet Location December 31, Balance Sheet Location December 31, Commodity contracts Other current assets $ 0.1 Accrued expenses $ 2.6 Commodity contracts Other assets — Other noncurrent liabilities 0.1 Total derivatives designated as hedging instruments $ 0.1 $ 2.7 (a) As of December 31, 2015, the Company had commodity hedge agreements with two counterparties. Amounts recorded as liabilities for the Company’s commodity contracts were payable to both counterparties. The Company has master netting agreements with its counterparties and accordingly has netted in its consolidated balance sheets $0.1 million of contracts that were in receivable positions against its contracts in payable positions.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2016
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements: The Company’s financial instruments are measured and reported at their estimated fair value. Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction. When available, the Company uses quoted prices in active markets to determine the fair values for its financial instruments (level one inputs) or, absent quoted market prices, observable market-corroborated inputs over the term of the financial instruments (level two inputs). The Company does not have any unobservable inputs that are not corroborated by market inputs (level three inputs). The Company holds marketable securities associated with its non-qualified retirement plan, which are valued based on readily available quoted market prices. The Company utilizes derivative instruments to manage its risk of changes in natural gas prices. The fair value of the natural gas derivative instruments are determined using market data of forward prices for all of the Company’s contracts. The estimated fair values for each type of instrument are presented below (in millions). June 30, Level One Level Two Level Three Asset Class: Mutual fund investments in a non-qualified retirement plan (a) $ 1.7 $ 1.7 $ — $ — Derivatives – natural gas instruments, net 0.2 — 0.2 — Total Assets $ 1.9 $ 1.7 $ 0.2 $ — Liability Class: Liabilities related to non-qualified retirement plan $ (1.7 ) $ (1.7 ) $ — $ — Derivatives – natural gas instruments, net (0.5 ) — (0.5 ) — Total Liabilities $ (2.2 ) $ (1.7 ) $ (0.5 ) $ — (a) Includes mutual fund investments of approximately 20% in the common stock of large-cap U.S. companies, 10% in the common stock of small to mid-cap U.S. companies, 5% in international companies, 10% in bond funds, 20% in short-term investments and 35% in blended funds. December 31, Level One Level Two Level Three Asset Class: Mutual fund investments in a non-qualified retirement plan (a) $ 1.6 $ 1.6 $ — $ — Total Assets $ 1.6 $ 1.6 $ — $ — Liability Class: Liabilities related to non-qualified retirement plan $ (1.6 ) $ (1.6 ) $ — $ — Derivatives – natural gas instruments, net (2.6 ) — (2.6 ) — Total Liabilities $ (4.2 ) $ (1.6 ) $ (2.6 ) $ — (a) Includes mutual fund investments of approximately 20% in the common stock of large-cap U.S. companies, 5% in the common stock of small to mid-cap U.S. companies, 5% in the common stock of international companies, 5% in bond funds, 35% in short-term investments and 30% in blended funds. Cash and cash equivalents, accounts receivable (net of allowance for bad debts) and payables are carried at cost, which approximates fair value due to their liquid and short-term nature. The Company’s investments related to its nonqualified retirement plan of $1.7 million and $1.6 million at June 30, 2016 , and December 31, 2015 , respectively, are stated at fair value based on quoted market prices. As of June 30, 2016 , the estimated amount a third-party would pay for the Company’s fixed-rate 4.875% senior notes due July 2024, based on available trading information, totaled $233.0 million (level two) compared with the aggregate principal amount at maturity of $250.0 million . The estimated amount a third-party would pay at June 30, 2016 , for the amounts outstanding under the Company’s term loan and revolving credit facility, based upon available bid information received from the Company’s lender, totaled $497.1 million (level two) compared with the aggregate principal balance of $506.5 million .

Earnings per Share

Earnings per Share	6 Months Ended
	Jun. 30, 2016
Earnings Per Share [Abstract]
Earnings per Share	Earnings per Share: The Company calculates earnings per share using the two-class method. The two-class method requires allocating the Company’s net earnings to both common shares and participating securities. The following table sets forth the computation of basic and diluted earnings per common share (in millions, except for share and per-share data): Three months ended Six Months Ended 2016 2015 2016 2015 Numerator: Net earnings $ 6.3 $ 13.2 $ 56.0 $ 73.8 Less: net earnings allocated to participating securities (a) (0.1 ) (0.2 ) (0.3 ) (0.5 ) Net earnings available to common shareholders $ 6.2 $ 13.0 $ 55.7 $ 73.3 Denominator (in thousands): Weighted-average common shares outstanding, shares for basic earnings per share 33,784 33,682 33,766 33,654 Weighted-average awards outstanding (b) 3 19 3 21 Shares for diluted earnings per share 33,787 33,701 33,769 33,675 Net earnings per common share, basic $ 0.18 $ 0.39 $ 1.65 $ 2.18 Net earnings per common share, diluted $ 0.18 $ 0.39 $ 1.65 $ 2.18 (a) Weighted participating securities include RSUs and PSUs that receive non-forfeitable dividends and consist of 146,000 and 149,000 weighted participating securities for the three and six months ended June 30, 2016 , respectively, and 192,000 and 204,000 weighted participating securities for the three and six months ended June 30, 2015 , respectively. (b) For the calculation of diluted earnings per share, the Company uses the more dilutive of either the treasury stock method or the two-class method to determine the weighted-average number of outstanding common shares. In addition, the Company had 580,000 and 491,000 weighted-average equity awards outstanding for the three and six months ended June 30, 2016 , respectively, and 463,000 and 413,000 weighted-average equity awards for the three and six months ended June 30, 2015 , respectively, which were anti-dilutive and therefore not included in the diluted earnings per-share calculation.

Accounting Policies and Basis22

Accounting Policies and Basis of Presentation (Policies)	6 Months Ended
	Jun. 30, 2016
Accounting Policies [Abstract]
Equity Method Investments	The Company uses the equity method of accounting for equity securities when it has significant influence or when it has more than a minor ownership interest or more than a minor influence over the investee’s operations but does not have a controlling financial interest. The Company recognizes its share of the investee’s earnings or losses on a three -month lag as the investee’s financial information is not available on a timely basis.
Reclassifications	Reclassifications Certain prior year amounts have been reclassified from other noncurrent assets to long-term debt, net of current portion, to conform to the current year presentation as required by the new accounting standard on debt issuance costs (see Note 7).
Recent Accounting Pronouncements	Recent Accounting Pronouncements In June 2016, the Financial Accounting Standards Board (the “FASB”) issued guidance for estimating credit losses on certain types of financial instruments, including trade receivables, by introducing an approach based on expected losses. The expected loss approach will require entities to incorporate considerations of historical information, current information and reasonable and supportable forecasts. The guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The guidance requires a modified retrospective transition method and early adoption is permitted. The Company is currently evaluating the impact of the adoption of this guidance on its consolidated financial statements. In March 2016, the FASB issued guidance to simplify several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. The guidance is effective for fiscal years ending after December 15, 2016, and early adoption is permitted. The Company is currently evaluating the impact of the adoption of this guidance on its consolidated financial statements. In February 2016, the FASB issued guidance which requires lessees to recognize on their balance sheet a right-of-use asset which represents a lessee’s right to use the underlying asset. Under this guidance, an entity must also recognize a lease liability which represents a lessee’s obligation to make lease payments for the right to use the asset. In addition, the standard requires expanded qualitative and quantitative disclosures. The guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, and requires a modified retrospective transition method. The Company is currently evaluating the impact of the adoption of this guidance on its consolidated financial statements. In July 2015, the FASB issued guidance that requires entities to measure inventory within the scope of the standard at the lower of cost or net realizable value. “Net realizable value” is defined as the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation. The guidance is effective for fiscal years, and interim periods within those years, beginning after December 15, 2016. Early adoption is permitted. The Company does not plan to early adopt, and the Company does not expect that this guidance will have a material impact on its consolidated financial statements. In August 2014, the FASB issued guidance which requires management to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and to provide disclosure in the footnotes under certain circumstances. This guidance is effective for fiscal years ending after December 15, 2016, and interim periods within annual periods beginning after December 15, 2016, with early adoption permitted. The Company does not plan to early adopt, and the Company does not expect that this guidance will have a material impact on its consolidated financial statements. In May 2014, the FASB issued guidance to provide a single, comprehensive revenue recognition model for all contracts with customers. The new revenue recognition model supersedes existing revenue recognition guidance and requires revenue recognition to depict the transfer of promised goods or services to customers in an amount that reflects the consideration an entity expects to receive in exchange for those goods or services. This guidance is effective for fiscal years and interim periods with those years beginning after December 15, 2017, and early adoption is permitted. The guidance permits the use of either a full or modified retrospective or cumulative effect transition method. The Company is currently evaluating the impact of this guidance on its consolidated financial statements.

Inventories (Tables)

Inventories (Tables)	6 Months Ended
	Jun. 30, 2016
Inventory Disclosure [Abstract]
Inventories	Inventories consist of the following (in millions): June 30, December 31, Finished goods $ 186.0 $ 223.1 Raw materials and supplies 54.9 52.2 Total inventories $ 240.9 $ 275.3

Property, Plant and Equipment24

Property, Plant and Equipment, Net (Tables)	6 Months Ended
	Jun. 30, 2016
Property, Plant and Equipment [Abstract]
Property, plant and equipment	Property, plant and equipment, net, consists of the following (in millions): June 30, December 31, Land, buildings and structures and leasehold improvements $ 362.2 $ 347.3 Machinery and equipment 741.4 701.5 Office furniture and equipment 24.9 25.4 Mineral interests 171.2 169.6 Construction in progress 261.2 191.5 1,560.9 1,435.3 Less accumulated depreciation and depletion (670.4 ) (634.6 ) Property, plant and equipment, net $ 890.5 $ 800.7

Goodwill and Intangible Asset25

Goodwill and Intangible Assets, Net (Tables)	6 Months Ended
	Jun. 30, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Estimated lives of intangible assets	The estimated lives of the Company’s intangible assets are as follows: Intangible asset Estimated Lives Supply agreement 50 years SOP production rights 25 years Patents 10-20 years Developed technology 5 years Lease rights 25 years Customer and distributor relationships 10 years Trademarks 10 years Noncompete agreements 5 years Trade names Indefinite Water rights Indefinite

Long-term Debt (Tables)

Long-term Debt (Tables)	6 Months Ended
	Jun. 30, 2016
Debt Disclosure [Abstract]
Long-term debt	Long-term debt consists of the following (in millions): June 30, December 31, Term Loan due July 2021 $ 396.0 $ — Term Loan due May 2017 — 471.9 Revolving Credit Facility due August 2017 — 4.5 Revolving Credit Facility due July 2021 107.5 — 4.875% Senior Notes due July 2024 246.7 246.5 750.2 722.9 Less current portion (4.0 ) (4.9 ) Long-term debt $ 746.2 $ 718.0

Operating Segments (Tables)

Operating Segments (Tables)	6 Months Ended
	Jun. 30, 2016
Segment Reporting [Abstract]
Segment information	Segment information is as follows (in millions): Three Months Ended June 30, 2016 Salt Plant Nutrition (a) Corporate and Other (b) Total Sales to external customers $ 119.1 $ 47.8 $ 2.6 $ 169.5 Intersegment sales — 1.9 (1.9 ) — Shipping and handling cost 31.4 5.7 — 37.1 Operating earnings (loss) 23.3 4.7 (12.5 ) 15.5 Depreciation, depletion and amortization 11.3 8.4 1.3 21.0 Total assets (as of end of period) 899.1 702.7 54.8 1,656.6 Three Months Ended June 30, 2015 Salt Plant Nutrition (a) Corporate and Other (b) Total Sales to external customers $ 116.3 $ 64.1 $ 3.3 $ 183.7 Intersegment sales 0.1 2.8 (2.9 ) — Shipping and handling cost 35.1 5.7 — 40.8 Operating earnings (loss) 21.1 16.8 (13.9 ) 24.0 Depreciation, depletion and amortization 10.9 7.1 1.1 19.1 Total assets (as of end of period) 905.6 563.0 61.7 1,530.3 Six Months Ended June 30, 2016 Salt Plant Nutrition (a) Corporate and Other (b) Total Sales to external customers $ 411.2 $ 98.9 $ 5.1 $ 515.2 Intersegment sales — 2.1 (2.1 ) — Shipping and handling cost 114.4 12.1 — 126.5 Operating earnings (loss) 106.0 10.0 (26.2 ) 89.8 Depreciation, depletion and amortization 22.0 16.3 2.6 40.9 Six Months Ended June 30, 2015 Salt Plant Nutrition (a) Corporate and Other (b) Total Sales to external customers $ 433.0 $ 137.7 $ 6.0 $ 576.7 Intersegment sales 0.1 3.5 (3.6 ) — Shipping and handling cost 129.6 13.1 — 142.7 Operating earnings (loss) 98.1 37.6 (27.0 ) 108.7 Depreciation, depletion and amortization 21.8 14.1 2.3 38.2 (a) Plant nutrition segment assets include the investment in Produquímica. (b) Corporate and other includes corporate entities, records management operations and other incidental operations and eliminations. Operating earnings (loss) for corporate and other includes indirect corporate overhead, including costs for general corporate governance and oversight, as well as costs for the human resources, information technology, legal and finance functions.

Stockholders' Equity and Equi28

Stockholders' Equity and Equity Instruments (Tables)	6 Months Ended
	Jun. 30, 2016
Equity [Abstract]
Weighted average assumptions and fair value for options granted	The inputs used to calculate fair value for options granted in 2016 are included in the table below. Fair value of options granted $10.17 Exercise price $70.58 Expected term (years) 4.5 Expected volatility 24.4% Dividend yield 3.3% Risk-free rate of return 1.2%
Stock-based compensation activity	The following table summarizes stock-based compensation activity during the six months ended June 30, 2016 . Stock Options RSUs PSUs (a) Number Weighted-average exercise price Number Weighted-average fair value Number Weighted-average fair value Outstanding at December 31, 2015 353,087 $ 83.94 91,008 $ 80.65 77,365 $ 96.63 Granted 157,887 70.48 25,565 70.48 42,902 73.77 Exercised (b) (11,377 ) 62.52 — — — — Released from restriction (b) — — (51,324 ) 75.18 (10,258 ) 78.49 Cancelled/expired (17,033 ) 86.53 (2,265 ) 89.70 (9,219 ) 88.47 Outstanding at June 30, 2016 482,564 $ 79.95 62,984 $ 80.66 100,790 $ 89.50 (a) Until they vest, PSUs are included in the table at the target level at their grant date and at that level represent one share of common stock per PSU. The final performance period for the 2013 PSU grant was completed in 2015. The Company cancelled 5,263 PSUs in the first quarter of 2016 related to the 2013 PSU grant. (b) Common stock issued for exercised options and for vested and earned RSUs and PSUs was issued from treasury stock.
Components of and changes in accumulated other comprehensive income	The components of and changes in accumulated other comprehensive income (loss) (“AOCI”) as of and for the three and six months ended June 30, 2016 , and 2015 , are as follows (in millions): Three Months Ended June 30, 2016 (a) Gains and (Losses) on Cash Flow Hedges Defined Benefit Pension Foreign Currency Total Beginning balance $ (1.4 ) $ (3.7 ) $ (68.5 ) $ (73.6 ) Other comprehensive income (loss) before reclassifications (b) 0.7 — (3.3 ) (2.6 ) Amounts reclassified from accumulated other comprehensive loss 0.5 0.1 — 0.6 Net current period other comprehensive income (loss) 1.2 0.1 (3.3 ) (2.0 ) Ending balance $ (0.2 ) $ (3.6 ) $ (71.8 ) $ (75.6 ) Three Months Ended June 30, 2015 (a) Gains and (Losses) on Cash Flow Hedges Defined Benefit Pension Foreign Currency Total Beginning balance $ (2.0 ) $ (8.7 ) $ (54.3 ) $ (65.0 ) Other comprehensive income (loss) before reclassifications (b) 0.1 — 11.2 11.3 Amounts reclassified from accumulated other comprehensive loss 0.4 0.3 — 0.7 Net current period other comprehensive income (loss) 0.5 0.3 11.2 12.0 Ending balance $ (1.5 ) $ (8.4 ) $ (43.1 ) $ (53.0 ) Six Months Ended June 30, 2016 (a) Gains and (Losses) on Cash Flow Hedges Defined Benefit Pension Foreign Currency Total Beginning balance $ (1.6 ) $ (3.8 ) $ (102.9 ) $ (108.3 ) Other comprehensive income (loss) before reclassifications (b) 0.2 — 31.1 31.3 Amounts reclassified from accumulated other comprehensive loss 1.2 0.2 — 1.4 Net current period other comprehensive income (loss) 1.4 0.2 31.1 32.7 Ending balance $ (0.2 ) $ (3.6 ) $ (71.8 ) $ (75.6 ) Six Months Ended June 30, 2015 (a) Gains and (Losses) on Cash Flow Hedges Defined Benefit Pension Foreign Currency Total Beginning balance $ (2.0 ) $ (9.0 ) $ (4.5 ) $ (15.5 ) Other comprehensive income (loss) before reclassifications (b) (0.6 ) — (38.6 ) (39.2 ) Amounts reclassified from accumulated other comprehensive loss 1.1 0.6 — 1.7 Net current period other comprehensive income (loss) 0.5 0.6 (38.6 ) (37.5 ) Ending balance $ (1.5 ) $ (8.4 ) $ (43.1 ) $ (53.0 ) (a) With the exception of the cumulative foreign currency translation adjustment, for which no tax effect is recorded, the changes in the components of accumulated other comprehensive gain (loss) presented in the tables above are reflected net of applicable income taxes. (b) The Company recorded foreign exchange (gains) losses of $(4.9) million and $(26.7) million in the three and six months ended June 30, 2016 , respectively, and $(2.7) million and $14.6 million in the three and six months ended June 30, 2015 , respectively, in accumulated other comprehensive income (loss) related to intercompany notes which were deemed to be of long-term investment nature.
Reclassifications out of Accumulated Other Comprehensive Income	The amounts reclassified from AOCI to (income) expense for the three and six months ended June 30, 2016 , and 2015 , are shown below (in millions): Amount Reclassified from AOCI Three Months Ended Six Months Ended Line Item Impacted in the Consolidated Statement of Operations Gains and (losses) on cash flow hedges: Natural gas instruments $ 0.8 $ 1.9 Product cost (0.3 ) (0.7 ) Income tax expense (benefit) Reclassifications, net of income taxes 0.5 1.2 Amortization of defined benefit pension: Amortization of loss $ 0.1 $ 0.2 Product cost — — Income tax expense (benefit) Reclassifications, net of income taxes 0.1 0.2 Total reclassifications, net of income taxes $ 0.6 $ 1.4 Amount Reclassified from AOCI Three Months Ended Six Months Ended Line Item Impacted in the Consolidated Statement of Operations Gains and (losses) on cash flow hedges: Natural gas instruments $ 0.6 $ 1.7 Product cost (0.2 ) (0.6 ) Income tax expense (benefit) Reclassifications, net of income taxes 0.4 1.1 Amortization of defined benefit pension: Amortization of loss $ 0.3 $ 0.7 Product cost — (0.1 ) Income tax expense (benefit) Reclassifications, net of income taxes 0.3 0.6 Total reclassifications, net of income taxes $ 0.7 $ 1.7

Derivative Financial Instrume29

Derivative Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair value of hedged items	The following tables present the fair value of the Company’s hedged items as of June 30, 2016 , and December 31, 2015 (in millions): Asset Derivatives Liability Derivatives Derivatives designated as hedging instruments (a) Balance Sheet Location June 30, Balance Sheet Location June 30, Commodity contracts Other current assets $ 0.5 Accrued expenses $ 0.8 Commodity contracts Other assets 0.1 Other noncurrent liabilities 0.1 Total derivatives designated as hedging instruments $ 0.6 $ 0.9 (a) As of June 30, 2016 , the Company had commodity hedge agreements with two counterparties. Amounts recorded as liabilities for the Company’s commodity contracts were payable to one counterparty, and amounts recorded as assets were due from one counterparty. The Company has master netting agreements with its counterparties and accordingly has netted in its consolidated balance sheets $0.4 million of contracts that were in receivable positions against its contracts in payable positions. Asset Derivatives Liability Derivatives Derivatives designated as hedging instruments (a) Balance Sheet Location December 31, Balance Sheet Location December 31, Commodity contracts Other current assets $ 0.1 Accrued expenses $ 2.6 Commodity contracts Other assets — Other noncurrent liabilities 0.1 Total derivatives designated as hedging instruments $ 0.1 $ 2.7 (a) As of December 31, 2015, the Company had commodity hedge agreements with two counterparties. Amounts recorded as liabilities for the Company’s commodity contracts were payable to both counterparties. The Company has master netting agreements with its counterparties and accordingly has netted in its consolidated balance sheets $0.1 million of contracts that were in receivable positions against its contracts in payable positions.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2016
Fair Value Disclosures [Abstract]
Fair value measurements	The estimated fair values for each type of instrument are presented below (in millions). June 30, Level One Level Two Level Three Asset Class: Mutual fund investments in a non-qualified retirement plan (a) $ 1.7 $ 1.7 $ — $ — Derivatives – natural gas instruments, net 0.2 — 0.2 — Total Assets $ 1.9 $ 1.7 $ 0.2 $ — Liability Class: Liabilities related to non-qualified retirement plan $ (1.7 ) $ (1.7 ) $ — $ — Derivatives – natural gas instruments, net (0.5 ) — (0.5 ) — Total Liabilities $ (2.2 ) $ (1.7 ) $ (0.5 ) $ — (a) Includes mutual fund investments of approximately 20% in the common stock of large-cap U.S. companies, 10% in the common stock of small to mid-cap U.S. companies, 5% in international companies, 10% in bond funds, 20% in short-term investments and 35% in blended funds. December 31, Level One Level Two Level Three Asset Class: Mutual fund investments in a non-qualified retirement plan (a) $ 1.6 $ 1.6 $ — $ — Total Assets $ 1.6 $ 1.6 $ — $ — Liability Class: Liabilities related to non-qualified retirement plan $ (1.6 ) $ (1.6 ) $ — $ — Derivatives – natural gas instruments, net (2.6 ) — (2.6 ) — Total Liabilities $ (4.2 ) $ (1.6 ) $ (2.6 ) $ — (a) Includes mutual fund investments of approximately 20% in the common stock of large-cap U.S. companies, 5% in the common stock of small to mid-cap U.S. companies, 5% in the common stock of international companies, 5% in bond funds, 35% in short-term investments and 30% in blended funds.

Earnings per Share (Tables)

Earnings per Share (Tables)	6 Months Ended
	Jun. 30, 2016
Earnings Per Share [Abstract]
Computation of basic and diluted earnings per common share	The following table sets forth the computation of basic and diluted earnings per common share (in millions, except for share and per-share data): Three months ended Six Months Ended 2016 2015 2016 2015 Numerator: Net earnings $ 6.3 $ 13.2 $ 56.0 $ 73.8 Less: net earnings allocated to participating securities (a) (0.1 ) (0.2 ) (0.3 ) (0.5 ) Net earnings available to common shareholders $ 6.2 $ 13.0 $ 55.7 $ 73.3 Denominator (in thousands): Weighted-average common shares outstanding, shares for basic earnings per share 33,784 33,682 33,766 33,654 Weighted-average awards outstanding (b) 3 19 3 21 Shares for diluted earnings per share 33,787 33,701 33,769 33,675 Net earnings per common share, basic $ 0.18 $ 0.39 $ 1.65 $ 2.18 Net earnings per common share, diluted $ 0.18 $ 0.39 $ 1.65 $ 2.18 (a) Weighted participating securities include RSUs and PSUs that receive non-forfeitable dividends and consist of 146,000 and 149,000 weighted participating securities for the three and six months ended June 30, 2016 , respectively, and 192,000 and 204,000 weighted participating securities for the three and six months ended June 30, 2015 , respectively. (b) For the calculation of diluted earnings per share, the Company uses the more dilutive of either the treasury stock method or the two-class method to determine the weighted-average number of outstanding common shares. In addition, the Company had 580,000 and 491,000 weighted-average equity awards outstanding for the three and six months ended June 30, 2016 , respectively, and 463,000 and 413,000 weighted-average equity awards for the three and six months ended June 30, 2015 , respectively, which were anti-dilutive and therefore not included in the diluted earnings per-share calculation.

Accounting Policies and Basis32

Accounting Policies and Basis of Presentation - Additional Information (Details)	6 Months Ended
	Jun. 30, 2016
Accounting Policies [Abstract]
Lag period in recognizing investee's earnings	3 months

Equity Investment (Details)

Equity Investment (Details) BRL in Millions	1 Months Ended		3 Months Ended		6 Months Ended
	Dec. 31, 2015USD ($)	Dec. 31, 2015BRL	Jun. 30, 2016USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2016USD ($)	Jun. 30, 2015USD ($)
Schedule of Equity Method Investments [Line Items]
Aggregate purchase price					$ 4,700,000	$ 0
Net loss from equity investee			$ 1,700,000	$ 0	1,300,000	$ 0
Term Loan [Member] | Term Loan due May 2017 [Member]
Schedule of Equity Method Investments [Line Items]
Face amount	$ 100,000,000
Produquímica [Member]
Schedule of Equity Method Investments [Line Items]
Percentage of interest acquired	35.00%	35.00%
Aggregate purchase price	$ 114,100,000	BRL 452.4	4,700,000
Equity method investment basis difference	$ 115,000,000
Net loss from equity investee			$ 1,700,000		$ 1,300,000
Produquímica [Member] | Common Stock [Member]
Schedule of Equity Method Investments [Line Items]
Percentage of interest acquired	6.00%	6.00%
Produquímica [Member] | Preferred Stock [Member]
Schedule of Equity Method Investments [Line Items]
Percentage of interest acquired	29.00%	29.00%

Inventories (Details)

Inventories (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Inventory Disclosure [Abstract]
Finished goods	$ 186	$ 223.1
Raw materials and supplies	54.9	52.2
Total inventories	$ 240.9	$ 275.3

Property, Plant and Equipment35

Property, Plant and Equipment, Net (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 1,560.9	$ 1,435.3
Less accumulated depreciation and depletion	(670.4)	(634.6)
Property, plant and equipment, net	890.5	800.7
Land, Buildings and Structures and Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	362.2	347.3
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	741.4	701.5
Office Furniture and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	24.9	25.4
Mineral Interests [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	171.2	169.6
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 261.2	$ 191.5

Goodwill and Intangible Asset36

Goodwill and Intangible Assets, Net (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 1.1	$ 1.2	$ 2.1	$ 2.3
Acquired Indefinite-lived Intangible Assets [Line Items]
Goodwill	61.4		61.4		$ 58.1
Plant Nutrition [Member]
Acquired Indefinite-lived Intangible Assets [Line Items]
Goodwill	$ 55.3		$ 55.3		$ 51.7
Supply Agreement [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Lives			50 years
SOP Production Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Lives			25 years
Patents [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Lives			10 years
Patents [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Lives			20 years
Developed Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Lives			5 years
Lease Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Lives			25 years
Customer and Distributor Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Lives			10 years
Trademarks [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Lives			10 years
Noncompete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated Lives			5 years

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Foreign Federal [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 5.1	$ 3.6
Foreign Federal 2033 [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 11.4	6.4
Expiration date (beginning in 2033)	Dec. 31, 2033
State [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 1.4	$ 0.8
Expiration date (beginning in 2033)	Dec. 31, 2033
Canadian Provincial [Member]
Income Tax Examination [Line Items]
Total reassessments including interest	$ 94.4
Amount of security posted in the form of a performance bond	61.2
Amount of security posted in the form of cash	29.2
Amount of security payable	$ 4
Canadian Provincial [Member] | Minimum [Member]
Income Tax Examination [Line Items]
Years under examination	2,002
Canadian Provincial [Member] | Maximum [Member]
Income Tax Examination [Line Items]
Years under examination	2,011
Canadian Federal and Provincial [Member] | Tax Year 2004 Through 2006 [Member]
Income Tax Examination [Line Items]
Amount of security posted in the form of a performance bond	$ 20.6
Total reassessment amount including penalty and interest	95.6
Amount of security in the form of a bank letter guarantee	37.2
Canadian Federal and Provincial [Member] | Tax Year 2007 Through 2008 [Member]
Income Tax Examination [Line Items]
Amount of security posted in the form of a performance bond	9.2
Total reassessment amount including penalty and interest	33.8
Amount of security in the form of a bank letter guarantee	$ 10.1
Canadian Federal and Provincial [Member] | Minimum [Member] | Tax Year 2004 Through 2006 [Member]
Income Tax Examination [Line Items]
Years under examination	2,004
Canadian Federal and Provincial [Member] | Minimum [Member] | Tax Year 2007 Through 2008 [Member]
Income Tax Examination [Line Items]
Years under examination	2,007
Canadian Federal and Provincial [Member] | Maximum [Member] | Tax Year 2004 Through 2006 [Member]
Income Tax Examination [Line Items]
Years under examination	2,006
Canadian Federal and Provincial [Member] | Maximum [Member] | Tax Year 2007 Through 2008 [Member]
Income Tax Examination [Line Items]
Years under examination	2,008

Long-term Debt (Details)

Long-term Debt (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Long-term debt, total	$ 750.2	$ 722.9
Less current portion	(4)	(4.9)
Long-term debt	746.2	718
Revolving Credit Facility [Member] | Revolving Credit Facility due August 2017 [Member]
Debt Instrument [Line Items]
Long-term debt, total	$ 0	$ 4.5
Long term debt maturity date	Aug. 31, 2017	Aug. 31, 2017
Revolving Credit Facility [Member] | Revolving Credit Facility Due July 2021 [Member]
Debt Instrument [Line Items]
Long-term debt, total	$ 107.5	$ 0
Long term debt maturity date	Jul. 31, 2021	Jul. 31, 2021
Secured Debt [Member] | Term Loan Due July 2021 [Member]
Debt Instrument [Line Items]
Long-term debt, total	$ 396	$ 0
Long term debt maturity date	Jul. 31, 2021	Jul. 31, 2021
Secured Debt [Member] | Term Loan due May 2017 [Member]
Debt Instrument [Line Items]
Long-term debt, total	$ 0	$ 471.9
Long term debt maturity date	May 31, 2017	May 31, 2017
Senior Notes [Member] | 4.875% Senior Notes due July 2024 [Member]
Debt Instrument [Line Items]
Long-term debt, total	$ 246.7	$ 246.5
Long term debt maturity date	Jul. 31, 2024	Jul. 31, 2024
Senior notes, interest rate	4.875%	4.875%

Long-term Debt - Additional Inf

Long-term Debt - Additional Information (Details) - USD ($)	1 Months Ended		6 Months Ended
	Apr. 30, 2016	Apr. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Debt Instrument [Line Items]
Refinancing expense	$ 1,500,000		$ 1,500,000	$ 0
Debt issuance costs	4,600,000
Write-off of existing deferred financing costs	100,000
Secured Credit Agreement Due July 2021 [Member]
Debt Instrument [Line Items]
Debt issuance costs	6,100,000
Secured Credit Agreement Due July 2021 [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Variable interest rate		1.50%
Revolving Credit Facility [Member] | Revolving Credit Facility due August 2017 [Member]
Debt Instrument [Line Items]
Debt refinanced	125,000,000
Revolving Credit Facility [Member] | Secured Credit Agreement Due July 2021 [Member]
Debt Instrument [Line Items]
Face amount	300,000,000
Secured Debt [Member] | Term Loan due May 2017 [Member]
Debt Instrument [Line Items]
Debt refinanced	471,000,000
Secured Debt [Member] | Secured Credit Agreement Due July 2021 [Member]
Debt Instrument [Line Items]
Face amount	$ 400,000,000
Secured Debt [Member] | Term Loan [Member] | Accounting Standards Update 2015-03 [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Debt issuance costs			3,000,000		$ 600,000
Secured Debt [Member] | Term Loan [Member] | Accounting Standards Update 2015-03 [Member] | Deferred Charges [Member]
Debt Instrument [Line Items]
Debt issuance costs			$ (3,000,000)		$ (600,000)
Senior Notes [Member] | 4.875% Senior Notes due July 2024 [Member]
Debt Instrument [Line Items]
Senior notes, interest rate			4.875%		4.875%
Senior Notes [Member] | 4.875% Senior Notes due July 2024 [Member] | Accounting Standards Update 2015-03 [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Debt issuance costs			$ 3,300,000		$ 3,500,000
Senior Notes [Member] | 4.875% Senior Notes due July 2024 [Member] | Accounting Standards Update 2015-03 [Member] | Deferred Charges [Member]
Debt Instrument [Line Items]
Debt issuance costs			$ (3,300,000)		$ (3,500,000)

Commitments and Contingencies (

Commitments and Contingencies (Details) - Cote Blanche [Member] - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Mar. 31, 2015	Dec. 31, 2013
Loss Contingencies [Line Items]
Reserve for expected payments required to resolve the dispute			$ 5
Additional amount of reserve for expected payments required to resolve the dispute		$ 2
Interest rate	4.00%

Operating Segments (Details)

Operating Segments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Segment Reporting Information [Abstract]
Sales	$ 169.5	$ 183.7	$ 515.2	$ 576.7
Shipping and handling cost	37.1	40.8	126.5	142.7
Operating earnings (loss)	15.5	24	89.8	108.7
Depreciation, depletion and amortization	21	19.1	40.9	38.2
Total assets (as of end of period)	1,656.6	1,530.3	1,656.6	1,530.3	$ 1,624.8
Operating Segments [Member] | Salt [Member]
Segment Reporting Information [Abstract]
Sales	119.1	116.3	411.2	433
Shipping and handling cost	31.4	35.1	114.4	129.6
Operating earnings (loss)	23.3	21.1	106	98.1
Depreciation, depletion and amortization	11.3	10.9	22	21.8
Total assets (as of end of period)	899.1	905.6	899.1	905.6
Operating Segments [Member] | Plant Nutrition [Member]
Segment Reporting Information [Abstract]
Sales	47.8	64.1	98.9	137.7
Shipping and handling cost	5.7	5.7	12.1	13.1
Operating earnings (loss)	4.7	16.8	10	37.6
Depreciation, depletion and amortization	8.4	7.1	16.3	14.1
Total assets (as of end of period)	702.7	563	702.7	563
Corporate and Other [Member]
Segment Reporting Information [Abstract]
Sales	2.6	3.3	5.1	6
Shipping and handling cost	0	0	0	0
Operating earnings (loss)	(12.5)	(13.9)	(26.2)	(27)
Depreciation, depletion and amortization	1.3	1.1	2.6	2.3
Total assets (as of end of period)	54.8	61.7	54.8	61.7
Intersegment Sales [Member]
Segment Reporting Information [Abstract]
Sales	(1.9)	(2.9)	(2.1)	(3.6)
Intersegment Sales [Member] | Salt [Member]
Segment Reporting Information [Abstract]
Sales	0	0.1	0	0.1
Intersegment Sales [Member] | Plant Nutrition [Member]
Segment Reporting Information [Abstract]
Sales	$ 1.9	$ 2.8	$ 2.1	$ 3.5

Stockholders' Equity and Equi42

Stockholders' Equity and Equity Instruments - Plan Information (Details) $ in Millions	6 Months Ended
	Jun. 30, 2016USD ($)award_typeshares	Jun. 30, 2015USD ($)	May 31, 2015shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reissued shares of treasury stock (in shares)	11,003
Tax deficiency from equity compensation awards recorded as a reduction to additional paid-in capital | $	$ 0.2
Compensation expense recorded during period pursuant to stock-based compensation plans | $	$ 2.6	$ 3.3
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted (in shares)	157,887
Vesting period	4 years
Options expiration period	7 years
Fair value measurement method	Black-Scholes option valuation model
Reissued shares of treasury stock (in shares)	11,377
PSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs and PSUs granted (in shares)	42,902
Performance period of PSUs	3 years
Number of award types | award_type	2
Reissued shares of treasury stock (in shares)	10,258
TSR PSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value measurement method	Monte-Carlo simulation model
Performance period of PSUs	3 years
Minimum percentage of earnings (in hundredths)	0.00%
Maximum percentage of earnings (in hundredths)	150.00%
ROIC PSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Performance period of PSUs	3 years
Minimum percentage of earnings (in hundredths)	0.00%
Maximum percentage of earnings (in hundredths)	200.00%
RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs and PSUs granted (in shares)	25,565
Vesting period	3 years
Reissued shares of treasury stock (in shares)	51,324
2015 Incentive Award Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance (in shares)			3,000,000

Stockholders' Equity and Equi43

Stockholders' Equity and Equity Instruments - Summary of Fair Value Assumptions and Methodology (Details) - Stock Options [Member]	6 Months Ended
	Jun. 30, 2016$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of options granted (in dollars per share)	$ 10.17
Exercise price (in dollars per share)	$ 70.58
Expected term (years)	4 years 6 months
Expected volatility	24.40%
Dividend yield	3.30%
Risk-free rate of return	1.20%

Stockholders' Equity and Equi44

Stockholders' Equity and Equity Instruments - Activity (Details) - $ / shares	3 Months Ended	6 Months Ended
	Mar. 31, 2016	Jun. 30, 2016
Stock Options [Member]
Number
Outstanding at beginning of period (in shares)	353,087	353,087
Granted (in shares)		157,887
Exercised (in shares)		(11,377)
Cancelled/Expired (in shares)		(17,033)
Outstanding at end of period (in shares)		482,564
Weighted-average exercise price
Weighted-average exercise price at beginning of period (in dollars per share)	$ 83.94	$ 83.94
Weighted-average exercise price, Granted (in dollars per share)		70.48
Weighted-average exercise price, Exercised (in dollars per share)		62.52
Weighted-average exercise price, Cancelled/Expired (in dollars per share)		86.53
Weighted-average exercise price at end of period (in dollars per share)		$ 79.95
RSUs [Member]
Number
Outstanding at beginning of period (in shares)	91,008	91,008
Granted (in shares)		25,565
Released from restriction (in shares)		(51,324)
Cancelled/Expired (in shares)		(2,265)
Outstanding at end of period (in shares)		62,984
Weighted-average fair value
Weighted-average fair value at beginning of period (in dollars per share)	$ 80.65	$ 80.65
Weighted-average fair value, Granted (in dollars per share)		70.48
Weighted-average fair value, Released from restriction (in dollars per share)		75.18
Weighted-average fair value, Cancelled/Expired (in dollars per share)		89.70
Weighted-average fair value at end of period (in dollars per share)		$ 80.66
PSUs [Member]
Number
Outstanding at beginning of period (in shares)	77,365	77,365
Granted (in shares)		42,902
Released from restriction (in shares)		(10,258)
Cancelled/Expired (in shares)		(9,219)
Outstanding at end of period (in shares)		100,790
Weighted-average fair value
Weighted-average fair value at beginning of period (in dollars per share)	$ 96.63	$ 96.63
Weighted-average fair value, Granted (in dollars per share)		73.77
Weighted-average fair value, Released from restriction (in dollars per share)		78.49
Weighted-average fair value, Cancelled/Expired (in dollars per share)		88.47
Weighted-average fair value at end of period (in dollars per share)		$ 89.50
PSU at grant date (in shares per unit)		1
PSUs [Member] | 2013 Grant [Member]
Number
Cancelled/Expired (in shares)	(5,263)

Stockholders' Equity and Equi45

Stockholders' Equity and Equity Instruments - Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance			$ 639.7
Ending balance	$ 684.4		684.4
Losses (gains) on foreign exchange of intercompany notes of long-term nature	(4.9)	$ (2.7)	(26.7)	$ 14.6
Gains and (Losses) on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(1.4)	(2)	(1.6)	(2)
Other comprehensive income (loss) before reclassifications	0.7	0.1	0.2	(0.6)
Amounts reclassified from accumulated other comprehensive loss	0.5	0.4	1.2	1.1
Net current period other comprehensive income (loss)	1.2	0.5	1.4	0.5
Ending balance	(0.2)	(1.5)	(0.2)	(1.5)
Defined Benefit Pension [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(3.7)	(8.7)	(3.8)	(9)
Other comprehensive income (loss) before reclassifications	0	0	0	0
Amounts reclassified from accumulated other comprehensive loss	0.1	0.3	0.2	0.6
Net current period other comprehensive income (loss)	0.1	0.3	0.2	0.6
Ending balance	(3.6)	(8.4)	(3.6)	(8.4)
Foreign Currency [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(68.5)	(54.3)	(102.9)	(4.5)
Other comprehensive income (loss) before reclassifications	(3.3)	11.2	31.1	(38.6)
Amounts reclassified from accumulated other comprehensive loss	0	0	0	0
Net current period other comprehensive income (loss)	(3.3)	11.2	31.1	(38.6)
Ending balance	(71.8)	(43.1)	(71.8)	(43.1)
Total [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(73.6)	(65)	(108.3)	(15.5)
Other comprehensive income (loss) before reclassifications	(2.6)	11.3	31.3	(39.2)
Amounts reclassified from accumulated other comprehensive loss	0.6	0.7	1.4	1.7
Net current period other comprehensive income (loss)	(2)	12	32.7	(37.5)
Ending balance	$ (75.6)	$ (53)	$ (75.6)	$ (53)

Stockholders' Equity and Equi46

Stockholders' Equity and Equity Instruments - Amount Reclassified from AOCI (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Product cost	$ 91.1	$ 92.3	$ 244.8	$ 270.2
Income tax expense (benefit)	1	6.7	21	28.9
Gains and (losses) from cash flow hedges [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications, net of income taxes	(0.5)	(0.4)	(1.2)	(1.1)
Amortization of defined benefit pension [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications, net of income taxes	(0.1)	(0.3)	(0.2)	(0.6)
Reclassifications, net of income taxes [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications, net of income taxes	0.6	0.7	1.4	1.7
Reclassifications, net of income taxes [Member] | Gains and (losses) from cash flow hedges [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Product cost	0.8	0.6	1.9	1.7
Income tax expense (benefit)	(0.3)	(0.2)	(0.7)	(0.6)
Total reclassifications, net of income taxes	0.5	0.4	1.2	1.1
Reclassifications, net of income taxes [Member] | Amortization of defined benefit pension [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Product cost	0.1	0.3	0.2	0.7
Income tax expense (benefit)	0	0	0	(0.1)
Total reclassifications, net of income taxes	$ 0.1	$ 0.3	$ 0.2	$ 0.6

Derivative Financial Instrume47

Derivative Financial Instruments (Details) MMBTU in Millions, $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2016USD ($)MMBTUcounterparty	Dec. 31, 2015USD ($)MMBTUcounterparty
Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives	$ 0.6	$ 0.1
Liability Derivatives	$ 0.9	$ 2.7
Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Underlying risk	change in natural gas prices
Period through which natural gas is hedged	Dec. 31, 2017
Percent of forecasted usage to be hedged (up to 90%)	90.00%
Maximum period which the Company hedges in advance of forecasted purchase	36 months
Notional amount (in MMBtus) | MMBTU	2.6	2.8
Net losses to be reclassified from accumulated other comprehensive loss to earnings during the next 12 months	$ 0.4
Number of counterparties | counterparty	2	2
Netting of contracts in a receivable position against contracts in payable positions	$ 0.4	$ 0.1
Commodity Contracts [Member] | Designated as Hedging Instruments [Member] | Other Current Asset [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives	0.5	0.1
Commodity Contracts [Member] | Designated as Hedging Instruments [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives	0.1	0
Commodity Contracts [Member] | Designated as Hedging Instruments [Member] | Accrued Expenses [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives	0.8	2.6
Commodity Contracts [Member] | Designated as Hedging Instruments [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives	$ 0.1	$ 0.1

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($)	Jun. 30, 2016	Dec. 31, 2015
Liability Class:
Mutual fund investments percentage of fund invested in common stock of large-cap U.S. (in hundredths)	20.00%	20.00%
Mutual fund investments percentage of fund invested in common stock small to mid-cap U.S. (in hundredths)	10.00%	5.00%
Mutual fund investments percentage of fund invested in common stock of international companies (in hundredths)	5.00%	5.00%
Mutual fund investments percentage of fund invested in bond funds (in hundredths)	10.00%	5.00%
Mutual fund investments percentage of fund invested in short-term investments (in hundredths)	20.00%	35.00%
Mutual fund investments percentage of fund invested in blended funds (in hundredths)	35.00%	30.00%
Fair Value, Measurements, Recurring [Member]
Asset Class:
Mutual fund investments in a non-qualified retirement plan	$ 1,700,000	$ 1,600,000
Derivatives – natural gas instruments, net	200,000
Total Assets	1,900,000	1,600,000
Liability Class:
Liabilities related to non-qualified retirement plan	(1,700,000)	(1,600,000)
Derivatives – natural gas instruments, net	(500,000)	(2,600,000)
Total Liabilities	(2,200,000)	(4,200,000)
Fair Value, Measurements, Recurring [Member] | Level One [Member]
Asset Class:
Mutual fund investments in a non-qualified retirement plan	1,700,000	1,600,000
Derivatives – natural gas instruments, net	0
Total Assets	1,700,000	1,600,000
Liability Class:
Liabilities related to non-qualified retirement plan	(1,700,000)	(1,600,000)
Derivatives – natural gas instruments, net	0	0
Total Liabilities	(1,700,000)	(1,600,000)
Fair Value, Measurements, Recurring [Member] | Level Two [Member]
Asset Class:
Mutual fund investments in a non-qualified retirement plan	0	0
Derivatives – natural gas instruments, net	200,000
Total Assets	200,000	0
Liability Class:
Liabilities related to non-qualified retirement plan	0	0
Derivatives – natural gas instruments, net	(500,000)	(2,600,000)
Total Liabilities	(500,000)	(2,600,000)
Fair Value, Measurements, Recurring [Member] | Level Three [Member]
Asset Class:
Mutual fund investments in a non-qualified retirement plan	0	0
Derivatives – natural gas instruments, net	0
Total Assets	0	0
Liability Class:
Liabilities related to non-qualified retirement plan	0	0
Derivatives – natural gas instruments, net	0	0
Total Liabilities	$ 0	$ 0
4.875% Senior Notes [Member]
Debt Instrument [Line Items]
Senior notes, interest rate	4.875%
Fair value of senior notes	$ 233,000,000
Aggregate principal amount due at maturity	250,000,000
Term loan [Member]
Debt Instrument [Line Items]
Aggregate principal amount due at maturity	506,500,000
Fair value of credit agreement debt	$ 497,100,000

Earnings per Share (Details)

Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Numerator:
Net earnings	$ 6.3	$ 13.2	$ 56	$ 73.8
Less: net earnings allocated to participating securities	(0.1)	(0.2)	(0.3)	(0.5)
Net earnings available to common shareholders	$ 6.2	$ 13	$ 55.7	$ 73.3
Denominator (in thousands):
Weighted-average common shares outstanding, shares for basic earnings per share (in shares)	33,784	33,682	33,766	33,654
Weighted-average awards outstanding (in shares)	3	19	3	21
Shares for diluted earnings per share (in shares)	33,787	33,701	33,769	33,675
Net earnings per common share, basic (in dollars per share)	$ 0.18	$ 0.39	$ 1.65	$ 2.18
Net earnings per common share, diluted (in dollars per share)	$ 0.18	$ 0.39	$ 1.65	$ 2.18
Participating securities (in shares)	146	192	149	204
Weighted anti-dilutive awards outstanding (in shares)	580	463	491	413