| In millions, except per share items | Dec-31-17 | Dec-31-16 | Dec-31-15 | Dec-31-14 | Dec-31-13 | Dec-31-12 | Dec-31-11 | Dec-31-10 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| Cash flows from operating activities: | | | | | | | | |
| Net loss | -73.1 | -28.9 | -219.1 | -176.7 | -8.1 | -13.7 | -36.9 | -3.2 |
| Adjustments to reconcile net loss to net cash from (used in) operating activities: | | | | | | | | |
| Depreciation, depletion and amortization | 121.1 | 185.3 | 140.3 | 109.4 | 67.2 | 57.1 | 45.6 | 44.7 |
| Share-based compensation | 3.2 | 7.6 | 7.7 | 6.1 | 5.3 | 6.0 | 4.7 | 4.0 |
| Amortization of deferred financing costs | 10.8 | 11.5 | 10.6 | 3.5 | 3.7 | 4.4 | 2.5 | 2.3 |
| Gain on derivative instruments | -1.9 | -24.1 | 5.6 | 31.1 | | | 3.1 | 3.5 |
| (Gain) loss on foreign exchange | 3.1 | 0.7 | -3.7 | | | | | |
| Income from equity affiliates | -5.9 | -5.6 | -5.4 | | | | | |
| Changes in operating assets and liabilities: | | | | | | | | |
| Receivables | 35.6 | -4.4 | 2.0 | -0.4 | -7.6 | -12.9 | 5.5 | -4.7 |
| Inventories | 20.3 | 13.0 | 1.8 | 45.3 | -2.5 | -2.2 | -2.1 | 2.3 |
| Accounts payable and accrued expenses | -20.2 | 10.5 | -5.4 | -24.9 | 13.6 | 17.4 | 4.1 | 9.0 |
| Deferred revenue | -24.5 | -7.4 | -13.1 | -12.2 | -9.1 | -8.2 | -9.9 | -7.4 |
| Other assets and liabilities | 20.5 | 13.2 | -19.6 | 14.7 | 11.8 | -7.9 | 2.9 | -4.3 |
| Net cash provided by operating activities | 114.2 | 151.9 | 45.6 | 50.4 | 80.7 | 57.1 | 44.7 | 45.4 |
| |
| Cash flows from investing activities: | | | | | | | | |
| Additions to property, plant and equipment | -35.0 | -46.1 | -77.9 | -50.3 | -28.6 | -21.0 | -27.6 | -22.8 |
| Proceeds from sales of restricted investments | | | | 8.7 | 8.3 | 4.1 | 3.4 | 2.3 |
| Proceeds from sales of assets | | | | | | | | |
| Net cash (used in) provided by investing activities | 10.7 | -155.7 | -70.8 | -432.8 | -21.9 | -123.5 | -33.6 | -29.2 |
| |
| Cash flows from financing activities: | | | | | | | | |
| Borrowings from long-term debt, net of debt discount | | | | | | | | |
| Repayments of long-term debt | -82.1 | -70.4 | -148.1 | -955.2 | -28.1 | -44.8 | -73.6 | -20.4 |
| Borrowings on revolving lines of credit | 275.3 | 423.5 | 201.7 | 25.0 | 7.0 | 16.5 | 87.2 | 170.9 |
| Repayments of revolving lines of credit | -82.1 | -70.4 | -148.1 | -955.2 | -28.1 | -44.8 | -73.6 | -20.4 |
| Debt issuance costs and other refinancing costs | | -8.8 | -8.1 | -88.1 | -0.2 | -5.7 | -15.0 | -1.9 |
| Net cash provided by (used in) financing activities | -82.8 | 40.1 | 36.7 | 338.7 | -29.3 | 67.2 | 13.9 | -20.9 |
| |
| Supplemental disclosures of cash flow information: | | | | | | | | |
| Non-cash transactions: | | | | | | | | |
| Capital leases and other financing sources | 1.3 | 27.4 | 15.2 | 15.6 | 5.4 | 1.8 | 0.5 | 3.7 |
| Cash and cash equivalents, including restricted cash, end of period | | | | | | | | |
| Cash and cash equivalents | | | | | | | | |
| Restricted cash in Restricted investments, reclamation deposits and bond collateral | | | | | | | | |