Fair Value Option	9 Months Ended
Fair Value Option	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Option	8. Fair Value Option During the Current Nine Months, the Company elected to account for its 5.75% Convertible Notes under the fair value option. The fair value carrying amount and the contractual principal outstanding balance of the 5.75% Convertible Notes accounted for under the fair value option as of September 30, 2018 is $55.9 million and $111.0 million, respectively. The change of $17.2 million and $73.7 million in the fair value of the 5.75% Convertible Notes accounted for under the fair value option are included in the Company’s condensed consolidated statement of operations for the Current Quarter and Current Nine Months, respectively, within Other Income. The primary reason for electing the fair value option is for simplification and cost-benefit considerations of accounting for the 5.75% Convertible Notes (the hybrid financial instrument) at fair value in its entirety versus bifurcation of the embedded derivatives. The 5.75% Convertible Notes contain bifurcatable embedded derivatives and do not require settlement by physical delivery of non-financial assets. The significant inputs to the valuation of the 5.75% Convertible Notes at fair value are Level 1 inputs as they are based on the quoted prices of the notes in the active market.

The entire disclosure for a company's election to apply the fair value option for measurement and reporting of eligible financial assets and liabilities (as defined), as well as certain other eligible items (as defined) included in the statement of financial position, whether such option is elected for a single eligible item or a group of similar eligible items and is in addition to other disclosures concerning fair value which the company may be required to provide. Such disclosure might be expected to include: (1) for items included in the statement of financial position: (a) the reasons for electing a fair value option for each eligible item or group of similar eligible items; (b) if the fair value option is elected for some but not all eligible items within a group of similar eligible items: (i) a description of those similar items and the reasons for partial election and (ii) information of how the group of similar items relates to individual balance sheet line items; (c) for each line item in the statement of financial position that includes an item or items for which the fair value option has been elected: (i) information of how each line item in the statement of financial position relates to major categories of assets and liabilities presented in accordance with other fair value disclosures and (ii) the aggregate carrying amount of ineligible items included in each line item in the balance sheet, if any; (d) the difference between the aggregate fair value and the aggregate unpaid principal balance (assuming contractual principal amounts and fair value option elected) of: (i) loans and long-term receivables (other than securities otherwise reported at fair value) and (ii) long-term debt instruments; (e) for loans held as assets for which the fair value option has been elected: (i) the aggregate fair value of loans that are 90 days or more past due, (ii) if the policy is to recognize interest income separately from other changes in fair value, the aggregate fair value of loans in nonaccrual status, and (iii) the difference between the aggregate fair value and the aggregate unpaid principal balance for loans that are 90 days or more past due, in nonaccrual status, or both; (f) for investments that would have been accounted for under the equity method if the entity had not chosen to apply the fair value option, the information required for such investments, if material either individually or in the aggregate; (2) for items included in the income statement: (a) the amounts of gains and losses from fair value changes included in earnings and in which line in the income statement those gains and losses are reported whether or not combined with gains and losses from items required to be accounted for at fair value; (b) a description of how interest and dividends are measured and where they are reported in the income statement; (c) for loans and other receivables held as assets: (i) the estimated amount of gains or losses included in earnings attributable to changes in instrument-specific credit risk and (ii) how the gains or losses attributable to changes in instrument-specific credit risk were determined; (d) for liabilities with fair values that have been significantly affected during the reporting period by changes in the instrument-specific credit risk: (i) the estimated amount of gains and losses from fair value changes included in earnings that are attributable to changes in the instrument-specific credit risk, (ii) qualitative information about the reasons for those changes, and (iii) how the gains and losses attributable to changes in instrument-specific credit risk were determined; and (3) certain other disclosures as required or determined to be provided.