00100 - Statement - CONSOLIDATED BALANCE SHEETS link:presentationLink link:calculationLink link:definitionLink 00200 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME link:presentationLink link:calculationLink link:definitionLink 00400 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS link:presentationLink link:calculationLink link:definitionLink 40105 - Disclosure - Description of the business and recent developments: Basic and diluted net (loss) income per common share (Details) link:presentationLink link:calculationLink link:definitionLink 40201 - Disclosure - Property and equipment: Property and equipment, Table (Details) link:presentationLink link:calculationLink link:definitionLink 40301 - Disclosure - Accrued and other liabilities: (Details) link:presentationLink link:calculationLink link:definitionLink 40405 - Disclosure - Long-term debt: Convertible senior notes (Details) link:presentationLink link:calculationLink link:definitionLink 40406 - Disclosure - Long-term debt: Long-term debt maturities (Details) link:presentationLink link:calculationLink link:definitionLink 40501 - Disclosure - Income taxes: Components of (loss) income before income taxes (Details) link:presentationLink link:calculationLink link:definitionLink 40502 - Disclosure - Income taxes: Temporary differences comprising our net deferred tax assets (Details) link:presentationLink link:calculationLink link:definitionLink 40506 - Disclosure - Income taxes: Effective Income Tax Rate Reconciliation (Details) link:presentationLink link:calculationLink link:definitionLink 40602 - Disclosure - Commitments and contingencies: Future minimum payments under capital lease agreements (Details) link:presentationLink link:calculationLink link:definitionLink 40603 - Disclosure - Commitments and contingencies: Future minimum payments under capital lease agreements, continued (Details) link:presentationLink link:calculationLink link:definitionLink 40606 - Disclosure - Commitments and contingencies: Future minimum annual payments under operating lease arrangements (Details) link:presentationLink link:calculationLink link:definitionLink 00090 - Document - Document and Entity Information link:presentationLink link:calculationLink link:definitionLink 00105 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) link:presentationLink link:calculationLink link:definitionLink 00205 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) link:presentationLink link:calculationLink link:definitionLink 00300 - Statement - CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY link:presentationLink link:calculationLink link:definitionLink 00405 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS link:presentationLink link:calculationLink link:definitionLink 10101 - Disclosure - Description of the business and summary of significant accounting policies: link:presentationLink link:calculationLink link:definitionLink 10201 - Disclosure - Property and equipment: link:presentationLink link:calculationLink link:definitionLink 10301 - Disclosure - Accrued and other liabilities: link:presentationLink link:calculationLink link:definitionLink 10401 - Disclosure - Long-term debt: link:presentationLink link:calculationLink link:definitionLink 10501 - Disclosure - Income taxes: link:presentationLink link:calculationLink link:definitionLink 10601 - Disclosure - Commitments and contingencies: link:presentationLink link:calculationLink link:definitionLink 10701 - Disclosure - Stockholders' equity: link:presentationLink link:calculationLink link:definitionLink 10801 - Disclosure - Stock option and award plan: link:presentationLink link:calculationLink link:definitionLink 10901 - Disclosure - Related party transactions: link:presentationLink link:calculationLink link:definitionLink 11001 - Disclosure - Geographic information: link:presentationLink link:calculationLink link:definitionLink 11101 - Disclosure - Quarterly financial information (unaudited): link:presentationLink link:calculationLink link:definitionLink 11201 - Disclosure - Subsequent Events: link:presentationLink link:calculationLink link:definitionLink 11301 - Disclosure - Schedule II VALUATION AND QUALIFYING ACCOUNTS link:presentationLink link:calculationLink link:definitionLink 20102 - Disclosure - Description of the business and summary of significant accounting policies: (Policies) link:presentationLink link:calculationLink link:definitionLink 30103 - Disclosure - Description of the business and summary of significant accounting policies: (Tables) link:presentationLink link:calculationLink link:definitionLink 30203 - Disclosure - Property and equipment: (Tables) link:presentationLink link:calculationLink link:definitionLink 30303 - Disclosure - Accrued and other liabilities: (Tables) link:presentationLink link:calculationLink link:definitionLink 30403 - Disclosure - Long-term debt: (Tables) link:presentationLink link:calculationLink link:definitionLink 30503 - Disclosure - Income taxes: (Tables) link:presentationLink link:calculationLink link:definitionLink 30603 - Disclosure - Commitments and contingencies: (Tables) link:presentationLink link:calculationLink link:definitionLink 30703 - Disclosure - Stockholders' equity: (Tables) link:presentationLink link:calculationLink link:definitionLink 30803 - Disclosure - Stock option and award plan: (Tables) link:presentationLink link:calculationLink link:definitionLink 31003 - Disclosure - Geographic information: (Tables) link:presentationLink link:calculationLink link:definitionLink 31103 - Disclosure - Quarterly financial information (unaudited): (Tables) link:presentationLink link:calculationLink link:definitionLink 40101 - Disclosure - Description of the business and summary of significant accounting policies: (Details) link:presentationLink link:calculationLink link:definitionLink 40102 - Disclosure - Description of the business and recent developments: Financial Instruments (Details) link:presentationLink link:calculationLink link:definitionLink 40103 - Disclosure - Description of the business and recent developments: Property, Plant and Equipment (Details) link:presentationLink link:calculationLink link:definitionLink 40104 - Disclosure - Description of the business and recent developments: Number of shares yield after conversion (Details) link:presentationLink link:calculationLink link:definitionLink 40106 - Disclosure - Description of the business and recent developments: Recent accounting pronouncements (Details) link:presentationLink link:calculationLink link:definitionLink 40202 - Disclosure - Property and equipment: Property and equipment addiional information (Details) link:presentationLink link:calculationLink link:definitionLink 40203 - Disclosure - Property and equipment: Purchase and installment payment agreements (Details) link:presentationLink link:calculationLink link:definitionLink 40401 - Disclosure - Long-term debt: Debt extinguishment, redemption and new debt issuance- $250.0 million 2022 Notes (Details) link:presentationLink link:calculationLink link:definitionLink 40402 - Disclosure - Long-term debt: Senior unsecured notes- $200.0 million 2021 Notes (Details) link:presentationLink link:calculationLink link:definitionLink 40403 - Disclosure - Long-term debt: Limitations under the Indentures (Details) link:presentationLink link:calculationLink link:definitionLink 40404 - Disclosure - Long-term debt: Senior secured notes-2018 Notes (Details) link:presentationLink link:calculationLink link:definitionLink 40503 - Disclosure - Income taxes: Net operating loss carry-forwards (Details) link:presentationLink link:calculationLink link:definitionLink 40504 - Disclosure - Income taxes: Reconciliation of unrecognized tax benefits (Details) link:presentationLink link:calculationLink link:definitionLink 40601 - Disclosure - Commitments and contingencies: (Details) link:presentationLink link:calculationLink link:definitionLink 40604 - Disclosure - Commitments and contingencies: Gain on capital lease termination (Details) link:presentationLink link:calculationLink link:definitionLink 40605 - Disclosure - Commitments and contingencies: Current and potential litigation (Details) link:presentationLink link:calculationLink link:definitionLink 40607 - Disclosure - Commitments and contingencies: Unconditional purchase obligations (Details) link:presentationLink link:calculationLink link:definitionLink 40608 - Disclosure - Commitments and contingencies: Defined contribution plan (Details) link:presentationLink link:calculationLink link:definitionLink 40701 - Disclosure - Stockholders' equity: (Details) link:presentationLink link:calculationLink link:definitionLink 40702 - Disclosure - Stockholders' equity: Common stock buyback program: (Details) link:presentationLink link:calculationLink link:definitionLink 40703 - Disclosure - Stockholders' equity: Dividends on common stock and return of capital program (Details) link:presentationLink link:calculationLink link:definitionLink 40801 - Disclosure - Stock option and award plan: Incentive award plan (Details) link:presentationLink link:calculationLink link:definitionLink 40802 - Disclosure - Stock option and award plan: Incentive award plan, tables (Details) link:presentationLink link:calculationLink link:definitionLink 40803 - Disclosure - Stock option and award plan: Non-vested awards, tables (Details) link:presentationLink link:calculationLink link:definitionLink 40804 - Disclosure - Stock option and award plan: Incentive award plan, additional information (Details) link:presentationLink link:calculationLink link:definitionLink 40901 - Disclosure - Related party transactions: (Details) link:presentationLink link:calculationLink link:definitionLink 41001 - Disclosure - Geographic information (Details) link:presentationLink link:calculationLink link:definitionLink 41101 - Disclosure - Quarterly financial information (unaudited): (Details) link:presentationLink link:calculationLink link:definitionLink 41201 - Disclosure - Subsequent Events: (Details) link:presentationLink link:calculationLink link:definitionLink 41301 - Disclosure - Schedule II VALUATION AND QUALIFYING ACCOUNTS (Details) link:presentationLink link:calculationLink link:definitionLink