Basis of Presentation and Significant Accounting Policies (Policies)	9 Months Ended
Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Change in Accounting Estimates	The preparation of financial statements in conformity with U.S. 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 revenues and expenses during the reporting period. Actual results could differ from those estimates. For further information, see Note 1 in our Annual Report on Form 10-K for the year ended December 31, 2016.
Reclassifications	Certain amounts reported in the condensed consolidated statements of cash flows for prior periods have been reclassified to conform to the current reporting presentation.
New Accounting Pronouncements	Standards adopted in 2017 Inventory Measurement: In July 2015, the FASB issued updated guidance that simplifies the subsequent measurement of inventory. It replaced the former lower of cost or market test with the lower of cost or net realizable value test. Net realizable value is defined as the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. We adopted this new guidance prospectively in the first quarter of 2017; however, the adoption did not have a material impact on our consolidated financial statements. Share-based Compensation: In March 2016, the FASB issued updated guidance that simplified several aspects of accounting for share-based payments transactions, including income tax consequences. We adopted this new guidance in the first quarter of 2017. The most significant impact of adopting this new guidance is the required change in accounting for excess tax benefits (“windfalls”) and deficiencies (“shortfalls”) related to share-based compensation. Beginning in the first quarter of 2017, such windfalls and shortfalls are now reflected in the consolidated statements of operations as a tax benefit or expense, respectively, whereas previously, they were generally recognized in additional paid in capital in the condensed consolidated balance sheets. For the first nine months of 2017, we recognized $0.2 million of expense in the provision for income taxes related to net shortfall tax deficiencies from share-based payments. For the first nine months of 2016, $1.5 million of net shortfall tax deficiencies were recognized in additional paid-in capital. The new guidance also impacts the calculation of diluted earnings per share. When applying the treasury stock method to share-based payment awards, entities shall no longer include tax windfalls or shortfalls when calculating assumed proceeds to determine the awards dilutive effect on earnings per share. The adoption of this guidance did not materially impact our diluted earnings per share in each of the periods presented. In addition to the income tax consequences described above, the new guidance requires all windfall tax benefits related to share-based payments be reported as cash flows from operating activities along with all other income tax cash flows. Previously, windfall tax benefits from share-based payment arrangements were reported as cash flows from financing activities. The new guidance allows companies to elect either a prospective or retrospective application with respect to this statement of cash flows presentation. We have elected to apply this classification amendment prospectively. Since we did not have any windfall tax benefits in 2016, the prospective adoption did not impact comparability with the prior year. Finally, the new guidance allows for the accounting policy option to account for forfeitures as they occur or continue estimating expected forfeitures over the course of the vesting period as required under previous guidance. We have elected the accounting policy option to continue estimating forfeitures in determining share-based compensation expense resulting in no impact to our financial statements from the adoption of the new guidance. Standards not yet adopted Revenue Recognition: In May 2014, the FASB amended the existing accounting standards for revenue recognition. The amendments are based on the principle that revenue should be recognized 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 or services. The new guidance is effective for us in the first quarter of 2018. The amendments are to be applied using a retrospective or modified retrospective approach. As part of our assessment work to date, we have formed an implementation work team and conducted assessments of the new guidance across our primary revenue streams. Our process includes performing a review of representative contracts across our primary revenue streams and comparing historical accounting practices to the new standard. While we have not fully completed our evaluation of the impacts of these amendments, our performance obligations under customer contracts are primarily short-term in nature. Therefore, we currently anticipate the adoption will not have a material impact on the timing or amounts of revenue recognized in our consolidated financial statements; however, we anticipate incremental disclosures to be included in our consolidated financial statements regarding our revenue recognition policies and related amounts. We currently anticipate adopting the new guidance utilizing the modified retrospective method with the cumulative effect recognized as of our adoption date, January 1, 2018. Leases: In February 2016, the FASB issued updated guidance regarding accounting for leases. The new accounting standard provides principles for the recognition, measurement, presentation and disclosure of leases and requires lessees to recognize both assets and liabilities arising from financing and operating leases. The classification as either a financing or operating lease will determine whether lease expense is recognized based on an effective interest method basis or on a straight-line basis over the term of the lease, respectively. The new guidance is effective for us in the first quarter of 2019 with early adoption permitted. Based on our current lease portfolio, we anticipate the new guidance will require us to reflect additional assets and liabilities in our consolidated balance sheet; however, we have not yet completed an estimation of such amount and we are still evaluating the overall impact of the new guidance on our consolidated financial statements. Credit Losses: In June 2016, the FASB issued new guidance which requires financial assets measured at amortized cost basis to be presented at the net amount expected to be collected, including trade receivables. The new standard requires an entity to estimate its lifetime “expected credit loss” for such assets at inception which will generally result in the earlier recognition of allowances for losses. The new guidance is effective for us in the first quarter of 2020 with early adoption permitted in 2019. This guidance should be applied using a modified retrospective basis through a cumulative-effect adjustment to retained earnings as of the beginning of the period of adoption. We are currently evaluating the impact of the new guidance on our consolidated financial statements. Statement of Cash Flows: In August 2016, the FASB issued updated guidance that clarifies how certain cash receipts and cash payments are presented and classified in the statement of cash flows. This update provides guidance on eight specific cash flow issues. This guidance is effective for us in the first quarter of 2018 and should be applied using the retrospective transition method to each period presented. Early adoption is permitted but all changes must be adopted in the same period. We do not expect the adoption of this new guidance to have a material impact on the presentation of our consolidated statements of cash flows. Deferred Taxes on Intra-Entity Asset Transfers: In October 2016, the FASB amended the guidance related to the recognition of current and deferred income taxes for intra-entity asset transfers. Under current U.S. GAAP, recognition of income taxes on intra-entity asset transfers is prohibited until the asset has been sold to an outside party. This update requires that entities recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. This update does not change U.S. GAAP for the pre-tax effects of an intra-entity asset transfer or for an intra-entity transfer of inventory. This guidance is effective for us in the first quarter of 2018 and should be applied using a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. We are currently evaluating the impact of the new guidance on our consolidated financial statements. Restricted Cash Presentation: In November 2016, the FASB issued updated guidance that requires that the statement of cash flows explain the change during the period in the total of cash, cash equivalents, restricted cash and restricted cash equivalents. Therefore, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. This guidance is effective for us in the first quarter of 2018 with early adoption permitted and should be applied using a retrospective transition method to each period presented. At September 30, 2017 and December 31, 2016, we had $93.0 million and $7.4 million of restricted cash included in prepaid expenses and other current assets in the accompanying balance sheet. In the first nine months of 2017, we increased our restricted cash balance by depositing $84.9 million of cash with an escrow agent for the October 1, 2017 maturity of the unsecured convertible senior notes. See “Note 8 - Financing Arrangements and Fair Value of Financial Instruments” for additional information. We are continuing to evaluate the impact of the new guidance on the presentation of our consolidated financial statements. Goodwill Impairment Test: In January 2017, the FASB amended the guidance related to the accounting for goodwill impairments by eliminating step two from the goodwill impairment test. Under the new guidance, if the carrying amount of a reporting unit exceeds its fair value, an impairment loss shall be recognized in an amount equal to that excess, limited to the total amount of goodwill allocated to that reporting unit. This guidance is effective for us for goodwill impairment tests beginning after December 15, 2019. This guidance should be applied prospectively and early adoption is permitted. We are currently evaluating the impact of the new guidance on our consolidated financial statements.

Standards adopted in 2017

Inventory Measurement: In July 2015, the FASB issued updated guidance that simplifies the subsequent measurement of inventory. It replaced the former lower of cost or market test with the lower of cost or net realizable value test. Net realizable value is defined as the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. We adopted this new guidance prospectively in the first quarter of 2017; however, the adoption did not have a material impact on our consolidated financial statements.

Share-based Compensation: In March 2016, the FASB issued updated guidance that simplified several aspects of accounting for share-based payments transactions, including income tax consequences. We adopted this new guidance in the first quarter of 2017.

The most significant impact of adopting this new guidance is the required change in accounting for excess tax benefits (“windfalls”) and deficiencies (“shortfalls”) related to share-based compensation. Beginning in the first quarter of 2017, such windfalls and shortfalls are now reflected in the consolidated statements of operations as a tax benefit or expense, respectively, whereas previously, they were generally recognized in additional paid in capital in the condensed consolidated balance sheets. For the first nine months of 2017, we recognized $0.2 million of expense in the provision for income taxes related to net shortfall tax deficiencies from share-based payments. For the first nine months of 2016, $1.5 million of net shortfall tax deficiencies were recognized in additional paid-in capital.

The new guidance also impacts the calculation of diluted earnings per share. When applying the treasury stock method to share-based payment awards, entities shall no longer include tax windfalls or shortfalls when calculating assumed proceeds to determine the awards dilutive effect on earnings per share. The adoption of this guidance did not materially impact our diluted earnings per share in each of the periods presented.

In addition to the income tax consequences described above, the new guidance requires all windfall tax benefits related to share-based payments be reported as cash flows from operating activities along with all other income tax cash flows. Previously, windfall tax benefits from share-based payment arrangements were reported as cash flows from financing activities. The new guidance allows companies to elect either a prospective or retrospective application with respect to this statement of cash flows presentation. We have elected to apply this classification amendment prospectively. Since we did not have any windfall tax benefits in 2016, the prospective adoption did not impact comparability with the prior year.

Finally, the new guidance allows for the accounting policy option to account for forfeitures as they occur or continue estimating expected forfeitures over the course of the vesting period as required under previous guidance. We have elected the accounting policy option to continue estimating forfeitures in determining share-based compensation expense resulting in no impact to our financial statements from the adoption of the new guidance.

Standards not yet adopted

Revenue Recognition: In May 2014, the FASB amended the existing accounting standards for revenue recognition. The amendments are based on the principle that revenue should be recognized 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 or services. The new guidance is effective for us in the first quarter of 2018. The amendments are to be applied using a retrospective or modified retrospective approach. As part of our assessment work to date, we have formed an implementation work team and conducted assessments of the new guidance across our primary revenue streams. Our process includes performing a review of representative contracts across our primary revenue streams and comparing historical accounting practices to the new standard. While we have not fully completed our evaluation of the impacts of these amendments, our performance obligations under customer contracts are primarily short-term in nature. Therefore, we currently anticipate the adoption will not have a material impact on the timing or amounts of revenue recognized in our consolidated financial statements; however, we anticipate incremental disclosures to be included in our consolidated financial statements regarding our revenue recognition policies and related amounts. We currently anticipate adopting the new guidance utilizing the modified retrospective method with the cumulative effect recognized as of our adoption date, January 1, 2018.

Leases: In February 2016, the FASB issued updated guidance regarding accounting for leases. The new accounting standard provides principles for the recognition, measurement, presentation and disclosure of leases and requires lessees to recognize both assets and liabilities arising from financing and operating leases. The classification as either a financing or operating lease will determine whether lease expense is recognized based on an effective interest method basis or on a straight-line basis over the term of the lease, respectively. The new guidance is effective for us in the first quarter of 2019 with early adoption permitted. Based on our current lease portfolio, we anticipate the new guidance will require us to reflect additional assets and liabilities in our consolidated balance sheet; however, we have not yet completed an estimation of such amount and we are still evaluating the overall impact of the new guidance on our consolidated financial statements.

Credit Losses: In June 2016, the FASB issued new guidance which requires financial assets measured at amortized cost basis to be presented at the net amount expected to be collected, including trade receivables. The new standard requires an entity to estimate its lifetime “expected credit loss” for such assets at inception which will generally result in the earlier recognition of allowances for losses. The new guidance is effective for us in the first quarter of 2020 with early adoption permitted in 2019. This guidance should be applied using a modified retrospective basis through a cumulative-effect adjustment to retained earnings as of the beginning of the period of adoption. We are currently evaluating the impact of the new guidance on our consolidated financial statements.

Statement of Cash Flows: In August 2016, the FASB issued updated guidance that clarifies how certain cash receipts and cash payments are presented and classified in the statement of cash flows. This update provides guidance on eight specific cash flow issues. This guidance is effective for us in the first quarter of 2018 and should be applied using the retrospective transition method to each period presented. Early adoption is permitted but all changes must be adopted in the same period. We do not expect the adoption of this new guidance to have a material impact on the presentation of our consolidated statements of cash flows.

Deferred Taxes on Intra-Entity Asset Transfers: In October 2016, the FASB amended the guidance related to the recognition of current and deferred income taxes for intra-entity asset transfers. Under current U.S. GAAP, recognition of income taxes on intra-entity asset transfers is prohibited until the asset has been sold to an outside party. This update requires that entities recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. This update does not change U.S. GAAP for the pre-tax effects of an intra-entity asset transfer or for an intra-entity transfer of inventory. This guidance is effective for us in the first quarter of 2018 and should be applied using a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. We are currently evaluating the impact of the new guidance on our consolidated financial statements.

Restricted Cash Presentation: In November 2016, the FASB issued updated guidance that requires that the statement of cash flows explain the change during the period in the total of cash, cash equivalents, restricted cash and restricted cash equivalents. Therefore, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. This guidance is effective for us in the first quarter of 2018 with early adoption permitted and should be applied using a retrospective transition method to each period presented. At September 30, 2017 and December 31, 2016, we had $93.0 million and $7.4 million of restricted cash included in prepaid expenses and other current assets in the accompanying balance sheet. In the first nine months of 2017, we increased our restricted cash balance by depositing $84.9 million of cash with an escrow agent for the October 1, 2017 maturity of the unsecured convertible senior notes. See “Note 8 - Financing Arrangements and Fair Value of Financial Instruments” for additional information. We are continuing to evaluate the impact of the new guidance on the presentation of our consolidated financial statements.

Goodwill Impairment Test: In January 2017, the FASB amended the guidance related to the accounting for goodwill impairments by eliminating step two from the goodwill impairment test. Under the new guidance, if the carrying amount of a reporting unit exceeds its fair value, an impairment loss shall be recognized in an amount equal to that excess, limited to the total amount of goodwill allocated to that reporting unit. This guidance is effective for us for goodwill impairment tests beginning after December 15, 2019. This guidance should be applied prospectively and early adoption is permitted. We are currently evaluating the impact of the new guidance on our consolidated financial statements.