New accounting standards (Policies)	9 Months Ended
Sep. 30, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New accounting standards	New accounting standards In May 2014, the Financial Accounting Standards Board ("FASB"), in a joint effort with the International Accounting Standards Board ("IASB"), issued new accounting guidance to clarify the principles for recognizing revenue. This new guidance, as amended by additional guidance issued in 2015 and 2016, is encompassed in FASB Accounting Standards Codification Topic 606, Revenue from Contracts with Customers (“ASC 606”) and is designed to enhance the comparability of revenue recognition practices across entities, industries, jurisdictions and capital markets, and affects any entity that enters into contracts with customers or enters into contracts for the transfer of nonfinancial assets, unless those contracts are within the scope of other standards. The new guidance establishes principles for reporting information to users of financial statements about the nature, amount, timing, and uncertainty of revenue and cash flows arising from an entity's contracts with customers. The core principle of the new guidance is that an entity recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and services. The Company adopted the new standard on January 1, 2018, applying the modified retrospective method to all of its contracts; as a result, the Company recognized the cumulative effect of adopting the guidance as a $1.2 million increase to the Company's opening balance of retained earnings on the adoption date. In addition, in connection with its adoption of the new guidance, the Company reclassified the reserve for product returns from a reduction of receivables to a liability. The reserve for returns and allowances was $4.6 million at September 30, 2018. The adoption of this guidance did not have a material impact on the Company's consolidated results of operations, cash flows and financial position. Additional information and disclosures required by this new standard are contained in Note 3. In February 2016, the FASB issued guidance that will change the requirements for accounting for leases. Under the new guidance, lessees (including lessees under both leases classified as finance leases, which are to be classified based on criteria similar to that applicable to capital leases under current guidance, and leases classified as operating leases) will recognize a right-to-use asset and a lease liability on the balance sheet, initially measured as the present value of lease payments under the lease. Under current guidance, operating leases are not recognized on the balance sheet. The standard is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is permitted. The new standard must be adopted using a modified retrospective transition approach for leases, subject to an option to elect certain practical expedients. As a result, companies can elect to apply the transition approach either for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements or for leases existing at, or entered into after, the adoption date. The Company is currently evaluating this guidance to determine its impact on the Company’s consolidated results of operations, cash flows and financial position. In October 2016, the FASB issued new guidance requiring companies to recognize the income tax effects of intra-entity sales and transfers of assets, other than inventory, in the income statement as income tax expense (or benefit) in the period in which the transfer occurs. Previously, recognition was prohibited until the assets were sold to an outside party or otherwise utilized. The Company adopted the new standard on January 1, 2018 using the modified retrospective method of adoption; as a result, the Company recognized the cumulative effect of adopting the guidance as a $1.8 million increase to the Company's opening balance of retained earnings on the adoption date. The adoption of this guidance did not have a material impact on the Company's consolidated results of operations, cash flows and financial position. In March 2017, the FASB issued guidance for employers that sponsor defined benefit pension or other postretirement benefit plans. The guidance requires that these employers disaggregate specified components of net periodic pension cost and net periodic postretirement benefit cost (collectively, "net benefit cost"). Specifically, the guidance generally requires employers to present in the income statement the service cost component of net benefit cost in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost are required to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations. The Company adopted this guidance on January 1, 2018; the impact was not material to the consolidated financial statements. In August 2017, the FASB issued guidance with the objective of improving the financial reporting of hedging relationships to better portray the economic results of an entity's risk management activities in its financial statements. The new guidance provides for changes to current designation and measurement guidance for qualifying hedging relationships and to the method of presenting hedge results. In addition, the new guidance includes certain targeted improvements to ease the application of current guidance related to the assessment of hedge effectiveness. The new guidance is effective for reporting periods beginning after December 15, 2018, but the guidance permits early adoptions, and the Company adopted the guidance effective October 1, 2018; the adoption did not result in any cumulative-effect adjustments to retained earnings. In February 2018, the FASB issued new guidance to address a narrow-scope financial reporting issue that arose as a consequence of the Tax Cuts and Jobs Act ("the TCJA"). Existing guidance requires that deferred tax liabilities and assets be adjusted for a change in tax laws or rates with the effect included in income from continuing operations in the reporting period that includes the enactment date. The guidance is applicable even in situations in which the related income tax effects of items in accumulated other comprehensive income were originally recognized in other comprehensive income (rather than in net income), such as amounts related to benefit plans and hedging activity. As a result, the tax effects of items within accumulated other comprehensive income (referred to as stranded tax effects) do not reflect the appropriate tax rate. The new guidance permits a reclassification of these amounts from accumulated other comprehensive income to retained earnings, thereby eliminating the stranded tax effects. The new guidance also requires certain disclosures about the stranded tax effects. The guidance is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. The new guidance can be applied either in the period of adoption or retrospectively to each period (or periods) in which the effect of the change in the U.S. federal corporate income tax rate under the TCJA is recognized. The Company is currently evaluating the impact this guidance will have on its consolidated financial statements. From time to time, new accounting guidance is issued by the FASB or other standard setting bodies that is adopted by the Company as of the effective date or, in some cases where early adoption is permitted, in advance of the effective date. The Company has assessed the recently issued guidance that is not yet effective and, unless otherwise indicated above, believes the new guidance will not have a material impact on the its consolidated results of operations, cash flows or financial position.

New accounting standards

In May 2014, the Financial Accounting Standards Board ("FASB"), in a joint effort with the International Accounting Standards Board ("IASB"), issued new accounting guidance to clarify the principles for recognizing revenue. This new guidance, as amended by additional guidance issued in 2015 and 2016, is encompassed in FASB Accounting Standards Codification Topic 606, Revenue from Contracts with Customers (“ASC 606”) and is designed to enhance the comparability of revenue recognition practices across entities, industries, jurisdictions and capital markets, and affects any entity that enters into contracts with customers or enters into contracts for the transfer of nonfinancial assets, unless those contracts are within the scope of other standards. The new guidance establishes principles for reporting information to users of financial statements about the nature, amount, timing, and uncertainty of revenue and cash flows arising from an entity's contracts with customers. The core principle of the new guidance is that an entity recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and services. The Company adopted the new standard on January 1, 2018, applying the modified retrospective method to all of its contracts; as a result, the Company recognized the cumulative effect of adopting the guidance as a $1.2 million increase to the Company's opening balance of retained earnings on the adoption date. In addition, in connection with its adoption of the new guidance, the Company reclassified the reserve for product returns from a reduction of receivables to a liability. The reserve for returns and allowances was $4.6 million at September 30, 2018. The adoption of this guidance did not have a material impact on the Company's consolidated results of operations, cash flows and financial position. Additional information and disclosures required by this new standard are contained in Note 3.

In February 2016, the FASB issued guidance that will change the requirements for accounting for leases. Under the new guidance, lessees (including lessees under both leases classified as finance leases, which are to be classified based on criteria similar to that applicable to capital leases under current guidance, and leases classified as operating leases) will recognize a right-to-use asset and a lease liability on the balance sheet, initially measured as the present value of lease payments under the lease. Under current guidance, operating leases are not recognized on the balance sheet. The standard is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. Early adoption is permitted. The new standard must be adopted using a modified retrospective transition approach for leases, subject to an option to elect certain practical expedients. As a result, companies can elect to apply the transition approach either for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements or for leases existing at, or entered into after, the adoption date. The Company is currently evaluating this guidance to determine its impact on the Company’s consolidated results of operations, cash flows and financial position.

In October 2016, the FASB issued new guidance requiring companies to recognize the income tax effects of intra-entity sales and transfers of assets, other than inventory, in the income statement as income tax expense (or benefit) in the period in which the transfer occurs. Previously, recognition was prohibited until the assets were sold to an outside party or otherwise utilized. The Company adopted the new standard on January 1, 2018 using the modified retrospective method of adoption; as a result, the Company recognized the cumulative effect of adopting the guidance as a $1.8 million increase to the Company's opening balance of retained earnings on the adoption date. The adoption of this guidance did not have a material impact on the Company's consolidated results of operations, cash flows and financial position.

In March 2017, the FASB issued guidance for employers that sponsor defined benefit pension or other postretirement benefit plans. The guidance requires that these employers disaggregate specified components of net periodic pension cost and net periodic postretirement benefit cost (collectively, "net benefit cost"). Specifically, the guidance generally requires employers to present in the income statement the service cost component of net benefit cost in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost are required to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations. The Company adopted this guidance on January 1, 2018; the impact was not material to the consolidated financial statements.

In August 2017, the FASB issued guidance with the objective of improving the financial reporting of hedging relationships to better portray the economic results of an entity's risk management activities in its financial statements. The new guidance provides for changes to current designation and measurement guidance for qualifying hedging relationships and to the method of presenting hedge results. In addition, the new guidance includes certain targeted improvements to ease the application of current guidance related to the assessment of hedge effectiveness. The new guidance is effective for reporting periods beginning after December 15, 2018, but the guidance permits early adoptions, and the Company adopted the guidance effective October 1, 2018; the adoption did not result in any cumulative-effect adjustments to retained earnings.

In February 2018, the FASB issued new guidance to address a narrow-scope financial reporting issue that arose as a consequence of the Tax Cuts and Jobs Act ("the TCJA"). Existing guidance requires that deferred tax liabilities and assets be adjusted for a change in tax laws or rates with the effect included in income from continuing operations in the reporting period that includes the enactment date. The guidance is applicable even in situations in which the related income tax effects of items in accumulated other comprehensive income were originally recognized in other comprehensive income (rather than in net income), such as amounts related to benefit plans and hedging activity. As a result, the tax effects of items within accumulated other comprehensive income (referred to as stranded tax effects) do not reflect the appropriate tax rate. The new guidance permits a reclassification of these amounts from accumulated other comprehensive income to retained earnings, thereby eliminating the stranded tax effects. The new guidance also requires certain disclosures about the stranded tax effects. The guidance is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. The new guidance can be applied either in the period of adoption or retrospectively to each period (or periods) in which the effect of the change in the U.S. federal corporate income tax rate under the TCJA is recognized. The Company is currently evaluating the impact this guidance will have on its consolidated financial statements.

From time to time, new accounting guidance is issued by the FASB or other standard setting bodies that is adopted by the Company as of the effective date or, in some cases where early adoption is permitted, in advance of the effective date. The Company has assessed the recently issued guidance that is not yet effective and, unless otherwise indicated above, believes the new guidance will not have a material impact on the its consolidated results of operations, cash flows or financial position.