Summary of Significant Accouting Policies Summary of Significant Accounting Policies (Policies)	12 Months Ended
Dec. 31, 2016
Accounting Policies [Abstract]
SIGNIFICANT ESTIMATES	SIGNIFICANT ESTIMATES The preparation of financial statements in conformity with accounting principles generally accepted in the U.S., which we refer to in this report as GAAP, requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of net sales and expenses during the reporting period. Significant areas requiring the use of estimates and measurement of uncertainty include determination of valuation for deferred tax assets, uncertain income tax positions, assessment of impairment of long-lived assets and goodwill, assessment of environmental matters, allocation of purchase price and fair value estimates for business combinations, equity-based compensation and pension and postretirement obligation assumptions. Actual results could differ from those estimates and assumptions.
Cash and Cash Equivalents, Policy [Policy Text Block]	CASH AND CASH EQUIVALENTS We consider all highly liquid instruments with maturities of three months or less to be cash equivalents. As of December 31, 2016 and 2015, we had cash and cash equivalents of $23.0 million and $5.6 million, respectively, on our Consolidated Balance Sheets.
SHORT-TERM INVESTMENTS AND RESTRICTED CASH	SHORT-TERM INVESTMENTS AND RESTRICTED CASH Our short-term investments are invested primarily in demand deposits, which have very short maturity periods, and therefore earn an interest rate commensurate with low-risk instruments. We do not attempt to hedge our exposure to interest rate risk for our short-term investments. Our restricted cash in which the underlying instrument has a term of greater than twelve months from the balance sheet date is classified as non-current and is included in “Other assets, net” on our Consolidated Balance Sheet. In the third quarter of 2016, an indemnity escrow account established in connection with the December 2014 sale of our former specialty business and mills was settled, resulting in the release of $2.3 million from a restricted cash escrow account, and as of December 31, 2016, we had no restricted cash classified as current on our Consolidated Balance Sheet. As of December 31, 2015, we had $2.3 million of restricted cash classified as current on our Consolidated Balance Sheet.
TRADE ACCOUNTS RECEIVABLE	TRADE ACCOUNTS RECEIVABLE Trade accounts receivable are stated at the amount we expect to collect. Trade accounts receivable do not bear interest. The allowance for doubtful accounts is our best estimate of the losses we expect will result from the inability of our customers to make required payments. We generally determine the allowance based on a combination of actual historical write-off experience and an analysis of specific customer accounts. As of December 31, 2016 and 2015, we had allowances for doubtful accounts of $1.5 million and $1.4 million, respectively. Bad debt expense, net, charged to selling, general and administrative expenses during 2016, 2015 and 2014 was $0.7 million, $0.2 million, and $0.1 million, respectively. All other activity impacting the allowance for doubtful accounts was immaterial for all periods.
PROPERTY, PLANT AND EQUIPMENT	PROPERTY, PLANT AND EQUIPMENT Property, plant and equipment are stated at cost, including assets acquired under capital lease obligations and any interest costs capitalized, less accumulated depreciation. Depreciation of buildings, equipment and other depreciable assets is determined using the straight-line method. Estimated useful lives generally range from 10 to 40 years for land improvements; 10 to 40 years for buildings and improvements; 5 to 25 years for machinery and equipment; and 2 to 15 years for office and other equipment. Assets we acquire through business combinations have estimated lives that are typically shorter than the assets we construct or buy new. We review the carrying value of our property, plant and equipment for impairment when events or changes in circumstances indicate that the carrying amount of those assets may not be recoverable. An impairment of property, plant and equipment exists when the carrying value is not considered to be recoverable through future undiscounted cash flows from operations and the carrying value of the assets exceeds the estimated fair value. During the first quarter of 2014, we permanently closed our Consumer Products segment's Long Island converting and distribution facility, the Long Island Closure. As a result of this closure, we impaired certain plant and equipment. In addition, as a result of the December 30, 2014, sale of our specialty business and mills, the Specialty Business Sale, certain property, plant and equipment associated with the divested mills were written off and included in our loss on divested assets. See Note 5, "Asset Divestiture" and Note 7, "Property, Plant and Equipment" for further discussion.
Intangible Assets, Finite-Lived, Policy [Policy Text Block]	INTANGIBLE ASSETS We use estimates in determining and assigning the fair value of the useful lives of intangible assets, the amount and timing of related future cash flows and fair values of the related operations. Our intangible assets have definite lives and are amortized over their estimated useful lives. We assess our intangible assets for impairment annually and when events or changes in circumstances indicate that the carrying amount may not be recoverable. We recorded intangible assets as a result of our acquisition of Cellu Tissue Holdings, Inc., or Cellu Tissue, on December 27, 2010. We also recorded intangible assets as a result of our December 2012 acquisition of a wood chipping facility. As a result of the Long Island Closure, we impaired certain intangible assets. In addition, during the fourth quarter of 2014 we determined that a customer relationship intangible asset related to our Pulp and Paperboard segment's wood chipping facility was fully impaired. As a result of the Specialty Business Sale, certain intangible assets associated with the divested mills were written off and included in our loss on divested assets. Finally, we recorded intangible assets as a result of our December 2016 acquisition of Manchester Industries. See Note 4, "Business Combinations," Note 5, "Asset Divestiture" and Note 8, "Goodwill and Intangible Assets" for further discussion.
GOODWILL AND INTANGIBLES	GOODWILL Goodwill from an acquisition represents the excess of the cost of a business acquired over the net of the amounts assigned to assets acquired, including identifiable intangible assets and liabilities assumed. We use estimates in determining and assigning the fair value of goodwill, including the amount and timing of related future cash flows and fair values of the related operations. Goodwill is not amortized but is tested for impairment annually as of November 1, as well as any time when events suggest impairment may have occurred. In the event the carrying value of the reporting unit in which our goodwill is assigned exceeds the estimated fair value of that reporting unit, an impairment loss would be recognized to the extent the carrying amount of the reporting unit exceeds its implied fair value. We recorded $229.5 million of goodwill in connection with our acquisition of Cellu Tissue in December 2010. All of the recorded goodwill was assigned to our Consumer Products segment and reporting unit. As a result of the Specialty Business Sale, a portion of goodwill was allocated to the divested mills and included in our loss on divested assets. We recorded $35.2 million of goodwill in connection with our acquisition of Manchester Industries. The goodwill from this acquisition is included in our Pulp and Paperboard segment. See Note 4, "Business Combinations," Note 5, "Asset Divestiture" and Note 8, "Goodwill and Intangible Assets" for further discussion. As of December 31, 2016 and 2015, we had $244.3 million and $209.1 million of goodwill included on our Consolidated Balance Sheet.
PENSION AND OTHER POSTRETIREMENT PLANS, POLICY [Policy Text Block]	PENSION AND OTHER POSTRETIREMENT EMPLOYEE BENEFITS The determination of pension plan expense and the requirements for funding our pension plans are based on a number of actuarial assumptions. Three critical assumptions are the discount rate applied to pension plan obligations, the rate of return on plan assets and mortality rates. For other postretirement employee benefit, or OPEB, plans, which provide certain health care and life insurance benefits to qualified retired employees, critical assumptions in determining OPEB income are the discount rate applied to benefit obligations, the assumed health care cost trend rates used in the calculation of benefit obligations and mortality rates. We also participate in multiemployer defined benefit pension plans. We make contributions to these multiemployer plans, as well as make contributions to a trust fund established to provide retiree medical benefits for a portion of these employees. The discount rate used in the determination of pension benefit obligations and pension expense is determined based on a review of long-term high-grade bonds and management's expectations. To determine the expected long-term rate of return on pension assets, we employ a process that analyzes historical long-term returns for various investment categories, as measured by appropriate indices. These indices are weighted based upon the extent to which plan assets are invested in the particular categories in arriving at our determination of a composite expected return. An increase in the discount rate or the rate of expected return on plan assets, all other assumptions remaining the same, would decrease pension plan expense, and conversely, a decrease in either of these measures would increase plan expense. The actual rates of return on plan assets may vary significantly from the assumptions used because of unanticipated changes in financial markets. The estimated net loss and prior service cost (credit) for the defined benefit pension and OPEB plans is amortized from accumulated other comprehensive loss into net periodic cost (benefit) in accordance with current accounting guidance. Net periodic pension and OPEB expenses are included in “Cost of sales” and “Selling, general and administrative expenses” in the Consolidated Statements of Operations. The expense is allocated to all business segments. In accordance with current accounting guidance governing defined benefit pension and other postretirement plans, at December 31, 2016 and 2015, long-term assets are recorded for overfunded single-employer plans and liabilities are recorded for underfunded single-employer plans. The funded status of a benefit plan is measured as the difference between plan assets at fair value and the projected benefit obligation. For underfunded single-employer plans, the estimated liability to be payable in the next twelve months is recorded as a current liability, with the remaining portion recorded as a long-term liability.
INCOME TAXES	INCOME TAXES Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the consolidated financial statement carrying amounts of existing assets and liabilities and their respective tax basis and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. The determination of our provision for income taxes requires significant judgment, the use of estimates, and the interpretation and application of complex tax laws. Significant judgment is required in assessing the timing and amounts of deductible and taxable items and the probability of sustaining uncertain tax positions. The benefits of uncertain tax positions are recorded in our consolidated financial statements only after determining a more-likely-than-not probability that the uncertain tax positions will withstand challenge, if any, from tax authorities. When facts and circumstances change, we reassess these probabilities and record any changes in the consolidated financial statements as appropriate.
REVENUE RECOGNITION	REVENUE RECOGNITION We recognize net sales when there is persuasive evidence of a sales agreement, the price to the customer is fixed and determinable, collection is reasonably assured, and title and the risk of loss passes to the customer. Shipping terms generally indicate when title and the risk of loss have passed. Revenue is recognized at shipment for sales when shipping terms are free on board, or FOB, shipping point. For sales where shipping terms are FOB destination, revenue is recognized when the goods are received by the customer. Revenue from both domestic and foreign sales of our products can involve shipping terms of either FOB shipping point or FOB destination or other shipping terms, depending upon the sales agreement with the customer. We had one customer in the Consumer Products segment, the Kroger Company, that accounted for approximately $232 million, or 13.4%, of our total company net sales in 2016 and approximately $215 million, or 12.3%, of our total company net sales in 2015. In 2014, we did not have any single customer that accounted for 10% or more of our total net sales. We provide for trade promotions, customer cash discounts, customer returns and other deductions as reductions to net sales in the same period as the related revenues are recognized. Provisions for these items are determined based on historical experience or specific customer arrangements. Revenue is recognized net of any sales taxes collected. Sales taxes, when collected, are recorded as a current liability and remitted to the appropriate governmental entities.
ENVIRONMENTAL	ENVIRONMENTAL As part of our corporate policy, we have an ongoing process to monitor, report on and comply with environmental requirements. Based on this ongoing process, accruals for environmental liabilities that are not within the scope of specific authoritative guidance related to accounting for asset retirement obligations or conditional asset retirement obligations are established in accordance with guidance related to accounting for contingencies. We estimate our environmental liabilities based on various assumptions and judgments, the specific nature of which varies in light of the particular facts and circumstances surrounding each environmental liability. These estimates typically reflect assumptions and judgments as to the probable nature, magnitude and timing of required investigation, remediation and monitoring activities and the probable cost of these activities. Currently, we are not aware of any material environmental liabilities and have accrued only for specific costs related to environmental matters that we have determined are probable and for which an amount can be reasonably estimated. Fees for professional services associated with environmental and legal issues are expensed as incurred.
STOCKHOLDERS' EQUITY	STOCKHOLDERS’ EQUITY On December 15, 2015, we announced that our Board of Directors had approved a stock repurchase program authorizing the repurchase of up to $100 million of our common stock. The repurchase program authorizes purchases of our common stock from time to time through open market purchases, negotiated transactions or other means, including accelerated stock repurchases and 10b5-1 trading plans in accordance with applicable securities laws and other restrictions. In 2016, we repurchased 1,355,946 shares of our outstanding common stock at an average price of $48.18 per share under this program. On December 15, 2014, we announced that our Board of Directors had approved a stock repurchase program authorizing the repurchase of up to $100 million of our common stock. We completed this program during the fourth quarter of 2015. In total, we repurchased 1,881,921 shares of our outstanding common stock at an average price of $53.13 per share under this program. On February 5, 2014, we announced that our Board of Directors had approved a stock repurchase program authorizing the repurchase of up to $100 million of our common stock. We completed this program during the third quarter of 2014. In total, we repurchased 1,574,748 shares of our outstanding common stock at an average price of $63.50 per share under this program.
DERIVATIVES	DERIVATIVES We had no activity during the years ended December 31, 2016, 2015 and 2014 that required hedge or derivative accounting treatment. However, to partially mitigate our exposure to market risk for changes in utility commodity pricing, we use firm price contracts to supply a portion of the natural gas requirements for our manufacturing facilities. As of December 31, 2016, these contracts covered approximately 20% of the expected average monthly requirements for 2017, including approximately 28% of the expected average monthly requirements for the first quarter. For the years ended December 31, 2016, 2015 and 2014, approximately 45%, 57%, and 58%, respectively, of our natural gas volumes were supplied through firm price contracts. These contracts qualify for treatment as “normal purchases or normal sales” under authoritative guidance and thus require no mark-to-market adjustment.

Summary of Significant Accouting Policies Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2016

The preparation of financial statements in conformity with accounting principles generally accepted in the U.S., which we refer to in this report as GAAP, requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of net sales and expenses during the reporting period. Significant areas requiring the use of estimates and measurement of uncertainty include determination of valuation for deferred tax assets, uncertain income tax positions, assessment of impairment of long-lived assets and goodwill, assessment of environmental matters, allocation of purchase price and fair value estimates for business combinations, equity-based compensation and pension and postretirement obligation assumptions. Actual results could differ from those estimates and assumptions.

Cash and Cash Equivalents, Policy [Policy Text Block]

CASH AND CASH EQUIVALENTS

We consider all highly liquid instruments with maturities of three months or less to be cash equivalents. As of December 31, 2016 and 2015, we had cash and cash equivalents of $23.0 million and $5.6 million, respectively, on our Consolidated Balance Sheets.

SHORT-TERM INVESTMENTS AND RESTRICTED CASH

Our short-term investments are invested primarily in demand deposits, which have very short maturity periods, and therefore earn an interest rate commensurate with low-risk instruments. We do not attempt to hedge our exposure to interest rate risk for our short-term investments. Our restricted cash in which the underlying instrument has a term of greater than twelve months from the balance sheet date is classified as non-current and is included in “Other assets, net” on our Consolidated Balance Sheet. In the third quarter of 2016, an indemnity escrow account established in connection with the December 2014 sale of our former specialty business and mills was settled, resulting in the release of $2.3 million from a restricted cash escrow account, and as of December 31, 2016, we had no restricted cash classified as current on our Consolidated Balance Sheet. As of December 31, 2015, we had $2.3 million of restricted cash classified as current on our Consolidated Balance Sheet.

TRADE ACCOUNTS RECEIVABLE

Trade accounts receivable are stated at the amount we expect to collect. Trade accounts receivable do not bear interest. The allowance for doubtful accounts is our best estimate of the losses we expect will result from the inability of our customers to make required payments. We generally determine the allowance based on a combination of actual historical write-off experience and an analysis of specific customer accounts. As of December 31, 2016 and 2015, we had allowances for doubtful accounts of $1.5 million and $1.4 million, respectively. Bad debt expense, net, charged to selling, general and administrative expenses during 2016, 2015 and 2014 was $0.7 million, $0.2 million, and $0.1 million, respectively. All other activity impacting the allowance for doubtful accounts was immaterial for all periods.

PROPERTY, PLANT AND EQUIPMENT

Property, plant and equipment are stated at cost, including assets acquired under capital lease obligations and any interest costs capitalized, less accumulated depreciation. Depreciation of buildings, equipment and other depreciable assets is determined using the straight-line method. Estimated useful lives generally range from 10 to 40 years for land improvements; 10 to 40 years for buildings and improvements; 5 to 25 years for machinery and equipment; and 2 to 15 years for office and other equipment. Assets we acquire through business combinations have estimated lives that are typically shorter than the assets we construct or buy new.

We review the carrying value of our property, plant and equipment for impairment when events or changes in circumstances indicate that the carrying amount of those assets may not be recoverable. An impairment of property, plant and equipment exists when the carrying value is not considered to be recoverable through future undiscounted cash flows from operations and the carrying value of the assets exceeds the estimated fair value.

During the first quarter of 2014, we permanently closed our Consumer Products segment's Long Island converting and distribution facility, the Long Island Closure. As a result of this closure, we impaired certain plant and equipment. In addition, as a result of the December 30, 2014, sale of our specialty business and mills, the Specialty Business Sale, certain property, plant and equipment associated with the divested mills were written off and included in our loss on divested assets. See Note 5, "Asset Divestiture" and Note 7, "Property, Plant and Equipment" for further discussion.

Intangible Assets, Finite-Lived, Policy [Policy Text Block]

INTANGIBLE ASSETS

We use estimates in determining and assigning the fair value of the useful lives of intangible assets, the amount and timing of related future cash flows and fair values of the related operations. Our intangible assets have definite lives and are amortized over their estimated useful lives. We assess our intangible assets for impairment annually and when events or changes in circumstances indicate that the carrying amount may not be recoverable.

We recorded intangible assets as a result of our acquisition of Cellu Tissue Holdings, Inc., or Cellu Tissue, on December 27, 2010. We also recorded intangible assets as a result of our December 2012 acquisition of a wood chipping facility. As a result of the Long Island Closure, we impaired certain intangible assets. In addition, during the fourth quarter of 2014 we determined that a customer relationship intangible asset related to our Pulp and Paperboard segment's wood chipping facility was fully impaired. As a result of the Specialty Business Sale, certain intangible assets associated with the divested mills were written off and included in our loss on divested assets. Finally, we recorded intangible assets as a result of our December 2016 acquisition of Manchester Industries. See Note 4, "Business Combinations," Note 5, "Asset Divestiture" and Note 8, "Goodwill and Intangible Assets" for further discussion.

GOODWILL AND INTANGIBLES

GOODWILL

Goodwill from an acquisition represents the excess of the cost of a business acquired over the net of the amounts assigned to assets acquired, including identifiable intangible assets and liabilities assumed. We use estimates in determining and assigning the fair value of goodwill, including the amount and timing of related future cash flows and fair values of the related operations. Goodwill is not amortized but is tested for impairment annually as of November 1, as well as any time when events suggest impairment may have occurred. In the event the carrying value of the reporting unit in which our goodwill is assigned exceeds the estimated fair value of that reporting unit, an impairment loss would be recognized to the extent the carrying amount of the reporting unit exceeds its implied fair value.

We recorded $229.5 million of goodwill in connection with our acquisition of Cellu Tissue in December 2010. All of the recorded goodwill was assigned to our Consumer Products segment and reporting unit. As a result of the Specialty Business Sale, a portion of goodwill was allocated to the divested mills and included in our loss on divested assets. We recorded $35.2 million of goodwill in connection with our acquisition of Manchester Industries. The goodwill from this acquisition is included in our Pulp and Paperboard segment. See Note 4, "Business Combinations," Note 5, "Asset Divestiture" and Note 8, "Goodwill and Intangible Assets" for further discussion. As of December 31, 2016 and 2015, we had $244.3 million and $209.1 million of goodwill included on our Consolidated Balance Sheet.

PENSION AND OTHER POSTRETIREMENT PLANS, POLICY [Policy Text Block]

PENSION AND OTHER POSTRETIREMENT EMPLOYEE BENEFITS

The determination of pension plan expense and the requirements for funding our pension plans are based on a number of actuarial assumptions. Three critical assumptions are the discount rate applied to pension plan obligations, the rate of return on plan assets and mortality rates. For other postretirement employee benefit, or OPEB, plans, which provide certain health care and life insurance benefits to qualified retired employees, critical assumptions in determining OPEB income are the discount rate applied to benefit obligations, the assumed health care cost trend rates used in the calculation of benefit obligations and mortality rates. We also participate in multiemployer defined benefit pension plans. We make contributions to these multiemployer plans, as well as make contributions to a trust fund established to provide retiree medical benefits for a portion of these employees.

The discount rate used in the determination of pension benefit obligations and pension expense is determined based on a review of long-term high-grade bonds and management's expectations. To determine the expected long-term rate of return on pension assets, we employ a process that analyzes historical long-term returns for various investment categories, as measured by appropriate indices. These indices are weighted based upon the extent to which plan assets are invested in the particular categories in arriving at our determination of a composite expected return.

An increase in the discount rate or the rate of expected return on plan assets, all other assumptions remaining the same, would decrease pension plan expense, and conversely, a decrease in either of these measures would increase plan expense. The actual rates of return on plan assets may vary significantly from the assumptions used because of unanticipated changes in financial markets.

The estimated net loss and prior service cost (credit) for the defined benefit pension and OPEB plans is amortized from accumulated other comprehensive loss into net periodic cost (benefit) in accordance with current accounting guidance.

Net periodic pension and OPEB expenses are included in “Cost of sales” and “Selling, general and administrative expenses” in the Consolidated Statements of Operations. The expense is allocated to all business segments. In accordance with current accounting guidance governing defined benefit pension and other postretirement plans, at December 31, 2016 and 2015, long-term assets are recorded for overfunded single-employer plans and liabilities are recorded for underfunded single-employer plans. The funded status of a benefit plan is measured as the difference between plan assets at fair value and the projected benefit obligation. For underfunded single-employer plans, the estimated liability to be payable in the next twelve months is recorded as a current liability, with the remaining portion recorded as a long-term liability.

INCOME TAXES

Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the consolidated financial statement carrying amounts of existing assets and liabilities and their respective tax basis and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date.

The determination of our provision for income taxes requires significant judgment, the use of estimates, and the interpretation and application of complex tax laws. Significant judgment is required in assessing the timing and amounts of deductible and taxable items and the probability of sustaining uncertain tax positions. The benefits of uncertain tax positions are recorded in our consolidated financial statements only after determining a more-likely-than-not probability that the uncertain tax positions will withstand challenge, if any, from tax authorities. When facts and circumstances change, we reassess these probabilities and record any changes in the consolidated financial statements as appropriate.

REVENUE RECOGNITION

We recognize net sales when there is persuasive evidence of a sales agreement, the price to the customer is fixed and determinable, collection is reasonably assured, and title and the risk of loss passes to the customer. Shipping terms generally indicate when title and the risk of loss have passed. Revenue is recognized at shipment for sales when shipping terms are free on board, or FOB, shipping point. For sales where shipping terms are FOB destination, revenue is recognized when the goods are received by the customer. Revenue from both domestic and foreign sales of our products can involve shipping terms of either FOB shipping point or FOB destination or other shipping terms, depending upon the sales agreement with the customer.

We had one customer in the Consumer Products segment, the Kroger Company, that accounted for approximately $232 million, or 13.4%, of our total company net sales in 2016 and approximately $215 million, or 12.3%, of our total company net sales in 2015. In 2014, we did not have any single customer that accounted for 10% or more of our total net sales.

We provide for trade promotions, customer cash discounts, customer returns and other deductions as reductions to net sales in the same period as the related revenues are recognized. Provisions for these items are determined based on historical experience or specific customer arrangements.

Revenue is recognized net of any sales taxes collected. Sales taxes, when collected, are recorded as a current liability and remitted to the appropriate governmental entities.

ENVIRONMENTAL

As part of our corporate policy, we have an ongoing process to monitor, report on and comply with environmental requirements. Based on this ongoing process, accruals for environmental liabilities that are not within the scope of specific authoritative guidance related to accounting for asset retirement obligations or conditional asset retirement obligations are established in accordance with guidance related to accounting for contingencies. We estimate our environmental liabilities based on various assumptions and judgments, the specific nature of which varies in light of the particular facts and circumstances surrounding each environmental liability. These estimates typically reflect assumptions and judgments as to the probable nature, magnitude and timing of required investigation, remediation and monitoring activities and the probable cost of these activities. Currently, we are not aware of any material environmental liabilities and have accrued only for specific costs related to environmental matters that we have determined are probable and for which an amount can be reasonably estimated. Fees for professional services associated with environmental and legal issues are expensed as incurred.

STOCKHOLDERS' EQUITY

STOCKHOLDERS’ EQUITY

On December 15, 2015, we announced that our Board of Directors had approved a stock repurchase program authorizing the repurchase of up to $100 million of our common stock. The repurchase program authorizes purchases of our common stock from time to time through open market purchases, negotiated transactions or other means, including accelerated stock repurchases and 10b5-1 trading plans in accordance with applicable securities laws and other restrictions. In 2016, we repurchased 1,355,946 shares of our outstanding common stock at an average price of $48.18 per share under this program.

On December 15, 2014, we announced that our Board of Directors had approved a stock repurchase program authorizing the repurchase of up to $100 million of our common stock. We completed this program during the fourth quarter of 2015. In total, we repurchased 1,881,921 shares of our outstanding common stock at an average price of $53.13 per share under this program.

On February 5, 2014, we announced that our Board of Directors had approved a stock repurchase program authorizing the repurchase of up to $100 million of our common stock. We completed this program during the third quarter of 2014. In total, we repurchased 1,574,748 shares of our outstanding common stock at an average price of $63.50 per share under this program.

DERIVATIVES

We had no activity during the years ended December 31, 2016, 2015 and 2014 that required hedge or derivative accounting treatment. However, to partially mitigate our exposure to market risk for changes in utility commodity pricing, we use firm price contracts to supply a portion of the natural gas requirements for our manufacturing facilities. As of December 31, 2016, these contracts covered approximately 20% of the expected average monthly requirements for 2017, including approximately 28% of the expected average monthly requirements for the first quarter. For the years ended December 31, 2016, 2015 and 2014, approximately 45%, 57%, and 58%, respectively, of our natural gas volumes were supplied through firm price contracts. These contracts qualify for treatment as “normal purchases or normal sales” under authoritative guidance and thus require no mark-to-market adjustment.