Recently Adopted Standards and Issued Accounting Standards	12 Months Ended
Dec. 31, 2017
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recently Adopted Standards and Issued Accounting Standards	Recently Adopted and Issued Accounting Standards Recently Adopted Accounting Standards — In March 2017, the Financial Accounting Standards Board (FASB) issued new guidance on the presentation of net periodic benefit cost in the statement of operations. It requires entities to disaggregate the current service cost component from the other components of net benefit cost. The service cost is presented with other current compensation costs in the statement of operations, while the other components are presented outside of income from operations. We elected to retrospectively adopt this guidance as of January 1, 2017. We do not have any service cost associated with our net benefit cost, as such, the impact of adopting this new guidance was to reclassify our defined benefit pension plan expense out of operating costs and expenses and to classify it as a non-operating expense below operating income. In January 2017, the FASB issued new guidance to simplify the measurement of goodwill impairments by eliminating Step 2 from the impairment test, which requires a hypothetical purchase price allocation to measure the amount of impairment loss. Instead, if the carrying amount of a reporting unit exceeds its fair value, an impairment loss is recognized in an amount equal to that excess, limited to the total amount of goodwill allocated to the reporting unit. We have elected to adopt this guidance as of January 1, 2017. In March 2016, the FASB issued new guidance which simplifies the accounting for share-based compensation arrangements, including the related income tax consequences and classification in the statement of cash flows. We elected to adopt this guidance effective January 1, 2016. The adoption used the modified retrospective transition method which had no impact on prior years. The impact of adopting this guidance was to record $14.7 million of previously unrecognized tax benefits, increasing deferred tax assets and retained earnings as of December 31, 2015. In January 2017, the FASB issued new guidance to clarify the definition of a business for acquisitions, with the intent to make application of the guidance more consistent and cost-efficient. We elected to adopt this guidance as of June 30, 2017, for acquisitions subsequent to our adoption date. We do not expect the adoption of this guidance to affect the treatment of future acquisitions or dispositions. In February 2018, the FASB issued new guidance that permits companies to reclassify the disproportionate tax effect in accumulated other comprehensive income ("AOCI") caused by the Tax Cuts and Jobs Act of 2017. We have adopted this guidance as of December 31, 2017. The impact of the adoption was to reclassify $19.4 million of tax effects related to our defined benefits plans from AOCI to retained earnings. Recently Issued Accounting Standards — In August 2016, the FASB issued new guidance related to classification of certain cash receipts and payments in the statement of cash flows. This new guidance was issued with the objective of reducing diversity in practice around eight specific types of cash flows. The new guidance is effective for fiscal years, and interim periods within those years, beginning after December 15, 2017. We are currently evaluating the impact of this guidance on our consolidated statements of cash flows. In June 2016, the FASB issued new guidance that changes the impairment model for most financial assets and certain other instruments. For trade and other receivables, held-to-maturity debt securities, loans and other instruments, entities will be required to use a new forward-looking “expected loss” model that will replace today’s “incurred loss” model and generally will result in the earlier recognition of allowances for losses. For available-for-sale debt securities with unrealized losses, entities will measure credit losses in a manner similar to current practice, except that the losses will be recognized as an allowance. The guidance is effective in 2020 with early adoption permitted in 2019. We are currently evaluating the impact of this guidance on our consolidated financial statements and the timing of adoption. In February 2016, the FASB issued new guidance on the accounting for leases. Under this guidance, lessees will be required to recognize a lease liability and a right-of-use asset for all leases (with the exception of short-term leases) at the commencement date. The new guidance is effective for fiscal years, and interim periods within those years, beginning after December 15, 2018. We are currently evaluating the impact of this guidance on our consolidated financial statements. In January 2016, the FASB issued new guidance on the recognition and measurement of financial instruments. This guidance primarily affects the accounting for equity method investments, financial liabilities under the fair value option and the presentation and disclosure requirements for financial instruments. The standard is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017. We are currently evaluating the impact of this guidance on our consolidated financial statements. In May 2014, the FASB issued new guidance on revenue recognition. Under this standard, an entity shall recognize revenue when it transfers 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 standard creates a five-step process that requires entities to exercise judgment when considering the terms of the contract(s) and all relevant facts and circumstances. This standard permits the use of either the retrospective or cumulative effect transition method and will be effective for us beginning in 2018. We are finalizing our assessment of the impact this new guidance will have on our consolidated financial statements. We expect to retrospectively apply this guidance. We do not expect that the adoption of this guidance will impact the timing of our revenue recognition. We do expect to have no more than $20 million of additional revenues in prior years from the impact of recording some revenue transactions on a gross basis that were previously recorded on a net basis. We expect that the adoption of the new standard will also require expanded footnote disclosure.

Recently Adopted and Issued Accounting Standards

Recently Adopted Accounting Standards — In March 2017, the Financial Accounting Standards Board (FASB) issued new guidance on the presentation of net periodic benefit cost in the statement of operations. It requires entities to disaggregate the current service cost component from the other components of net benefit cost. The service cost is presented with other current compensation costs in the statement of operations, while the other components are presented outside of income from operations. We elected to retrospectively adopt this guidance as of January 1, 2017. We do not have any service cost associated with our net benefit cost, as such, the impact of adopting this new guidance was to reclassify our defined benefit pension plan expense out of operating costs and expenses and to classify it as a non-operating expense below operating income.

In January 2017, the FASB issued new guidance to simplify the measurement of goodwill impairments by eliminating Step 2 from the impairment test, which requires a hypothetical purchase price allocation to measure the amount of impairment loss. Instead, if the carrying amount of a reporting unit exceeds its fair value, an impairment loss is recognized in an amount equal to that excess, limited to the total amount of goodwill allocated to the reporting unit. We have elected to adopt this guidance as of January 1, 2017.

In March 2016, the FASB issued new guidance which simplifies the accounting for share-based compensation arrangements, including the related income tax consequences and classification in the statement of cash flows. We elected to adopt this guidance effective January 1, 2016. The adoption used the modified retrospective transition method which had no impact on prior years. The impact of adopting this guidance was to record $14.7 million of previously unrecognized tax benefits, increasing deferred tax assets and retained earnings as of December 31, 2015.

In January 2017, the FASB issued new guidance to clarify the definition of a business for acquisitions, with the intent to make application of the guidance more consistent and cost-efficient. We elected to adopt this guidance as of June 30, 2017, for acquisitions subsequent to our adoption date. We do not expect the adoption of this guidance to affect the treatment of future acquisitions or dispositions.

In February 2018, the FASB issued new guidance that permits companies to reclassify the disproportionate tax effect in accumulated other comprehensive income ("AOCI") caused by the Tax Cuts and Jobs Act of 2017. We have adopted this guidance as of December 31, 2017. The impact of the adoption was to reclassify $19.4 million of tax effects related to our defined benefits plans from AOCI to retained earnings.

Recently Issued Accounting Standards — In August 2016, the FASB issued new guidance related to classification of certain cash receipts and payments in the statement of cash flows. This new guidance was issued with the objective of reducing diversity in practice around eight specific types of cash flows. The new guidance is effective for fiscal years, and interim periods within those years, beginning after December 15, 2017. We are currently evaluating the impact of this guidance on our consolidated statements of cash flows.

In June 2016, the FASB issued new guidance that changes the impairment model for most financial assets and certain other instruments. For trade and other receivables, held-to-maturity debt securities, loans and other instruments, entities will be required to use a new forward-looking “expected loss” model that will replace today’s “incurred loss” model and generally will result in the earlier recognition of allowances for losses. For available-for-sale debt securities with unrealized losses, entities will measure credit losses in a manner similar to current practice, except that the losses will be recognized as an allowance. The guidance is effective in 2020 with early adoption permitted in 2019. We are currently evaluating the impact of this guidance on our consolidated financial statements and the timing of adoption.

In February 2016, the FASB issued new guidance on the accounting for leases. Under this guidance, lessees will be required to recognize a lease liability and a right-of-use asset for all leases (with the exception of short-term leases) at the commencement date. The new guidance is effective for fiscal years, and interim periods within those years, beginning after December 15, 2018. We are currently evaluating the impact of this guidance on our consolidated financial statements.

In January 2016, the FASB issued new guidance on the recognition and measurement of financial instruments. This guidance primarily affects the accounting for equity method investments, financial liabilities under the fair value option and the presentation and disclosure requirements for financial instruments. The standard is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017. We are currently evaluating the impact of this guidance on our consolidated financial statements.

In May 2014, the FASB issued new guidance on revenue recognition. Under this standard, an entity shall recognize revenue when it transfers 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 standard creates a five-step process that requires entities to exercise judgment when considering the terms of the contract(s) and all relevant facts and circumstances. This standard permits the use of either the retrospective or cumulative effect transition method and will be effective for us beginning in 2018. We are finalizing our assessment of the impact this new guidance will have on our consolidated financial statements. We expect to retrospectively apply this guidance. We do not expect that the adoption of this guidance will impact the timing of our revenue recognition. We do expect to have no more than $20 million of additional revenues in prior years from the impact of recording some revenue transactions on a gross basis that were previously recorded on a net basis. We expect that the adoption of the new standard will also require expanded footnote disclosure.