Income Taxes	9 Months Ended
Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Accounting rules governing income taxes require that deferred tax assets and liabilities be recognized using enacted tax rates for the effect of temporary differences between the book and tax bases of recorded assets and liabilities. These rules also require that deferred tax assets be reduced by a valuation allowance if it is more likely than not that some portion or the entire deferred tax asset will not be realized. The company evaluates the realizability of its deferred tax assets by assessing its valuation allowance and by adjusting the amount of such allowance, if necessary. The factors used to assess the likelihood of realization are the company’s historical profitability, forecast of future taxable income and available tax-planning strategies that could be implemented to realize the net deferred tax assets. The company uses tax-planning strategies to realize or renew net deferred tax assets to avoid the potential loss of future tax benefits. A full valuation allowance is currently maintained for all U.S. and certain foreign deferred tax assets in excess of deferred tax liabilities. The company will record a tax provision or benefit for those international subsidiaries that do not have a full valuation allowance against their net deferred tax assets. Any profit or loss recorded for the company’s U.S. operations will have no provision or benefit associated with it due to such valuation allowance, except with respect to withholding taxes not creditable against future taxable income. As a result, the company’s provision or benefit for taxes may vary significantly depending on the geographic distribution of income. During the three months ended September 30, 2018, the company recognized a benefit of $6.6 million due to the release of a valuation allowance on certain foreign deferred tax assets (net operating losses) as a result of the identification of an additional source of taxable income available in prior periods. In the second quarter of 2017, the company elected to receive cash refunds of a portion of its U.S. alternative minimum tax (AMT) credit carryforwards in lieu of claiming bonus depreciation as provided by Internal Revenue Code Section 168(k)(4). The decision to make this election resulted in a tax benefit of $21.1 million in 2017.

Income Taxes

Accounting rules governing income taxes require that deferred tax assets and liabilities be recognized using enacted tax rates for the effect of temporary differences between the book and tax bases of recorded assets and liabilities. These rules also require that deferred tax assets be reduced by a valuation allowance if it is more likely than not that some portion or the entire deferred tax asset will not be realized.

The company evaluates the realizability of its deferred tax assets by assessing its valuation allowance and by adjusting the amount of such allowance, if necessary. The factors used to assess the likelihood of realization are the company’s historical profitability, forecast of future taxable income and available tax-planning strategies that could be implemented to realize the net deferred tax assets. The company uses tax-planning strategies to realize or renew net deferred tax assets to avoid the potential loss of future tax benefits.

A full valuation allowance is currently maintained for all U.S. and certain foreign deferred tax assets in excess of deferred tax liabilities. The company will record a tax provision or benefit for those international subsidiaries that do not have a full valuation allowance against their net deferred tax assets. Any profit or loss recorded for the company’s U.S. operations will have no provision or benefit associated with it due to such valuation allowance, except with respect to withholding taxes not creditable against future taxable income. As a result, the company’s provision or benefit for taxes may vary significantly depending on the geographic distribution of income.

During the three months ended September 30, 2018, the company recognized a benefit of $6.6 million due to the release of a valuation allowance on certain foreign deferred tax assets (net operating losses) as a result of the identification of an additional source of taxable income available in prior periods. In the second quarter of 2017, the company elected to receive cash refunds of a portion of its U.S. alternative minimum tax (AMT) credit carryforwards in lieu of claiming bonus depreciation as provided by Internal Revenue Code Section 168(k)(4). The decision to make this election resulted in a tax benefit of $21.1 million in 2017.