Income Taxes (Notes)	3 Months Ended
Dec. 31, 2017
Income Taxes [Abstract]
Income Tax Disclosure [Text Block]	Income Taxes The income tax provision for interim periods is comprised of tax on ordinary income (loss) provided at the most recent estimated annual effective tax rate, adjusted for the tax effect of discrete items. Management uses an estimated annual effective tax rate based on the forecasted pretax income (loss) and statutory tax rates in the various jurisdictions in which it operates. The Company’s effective tax rate differs from the U.S. statutory rate primarily due to state and local taxes, and differing statutory tax rates applied to the income of non-U.S. subsidiaries. The Company records the tax effect of certain discrete items, including the effects of changes in tax laws, tax rates and adjustments with respect to valuation allowances or other unusual or nonrecurring tax adjustments, in the interim period in which they occur, as an addition to, or reduction from, the income tax provision, rather than being included in the estimated effective annual income tax rate. In addition, jurisdictions with a projected loss for the year or a year-to-date loss where no tax benefit can be recognized are excluded from the estimated annual effective income tax rate. The Company is required to assess its deferred tax assets and the need for a valuation allowance at each reporting period. This assessment requires judgment on the part of management with respect to benefits that may be realized. The Company will record a valuation allowance against deferred tax assets when it is considered more likely than not that all or a portion of the deferred tax assets will not be realized. Effects of the Tax Cuts and Jobs Act On December 22, 2017, the President of the United States signed and enacted into law H.R. 1, the Tax Cuts and Jobs Act (“the Tax Reform”). Among the significant changes to the U.S. Internal Revenue Code, the Tax Reform lowers the U.S. federal corporate income tax rate from 35% to 21%, effective January 1, 2018. The Company will compute its income tax expense (benefit) for the September 30, 2018 tax year using a U.S. statutory tax rate of 24.5%. The 21% U.S. statutory tax rate will apply to fiscal years ending September 30, 2019 and thereafter. For the three months ended December 31, 2017, the Company recorded tax expense of $8.9 million related to the remeasurement of deferred tax assets and liabilities. The provisional remeasurement amount is anticipated to change as data becomes available allowing more accurate scheduling of certain deferred tax assets and liabilities. The Tax Reform also includes a one-time mandatory repatriation transition tax on previously untaxed accumulated and current earnings and profits (E&P) of certain of the Company’s foreign subsidiaries. To determine the amount of the transition tax, the Company must determine, in addition to other factors, the amount of post 1986 E&P of the relevant subsidiaries, as well as the amount of non-US income taxes paid on such earnings. The Company made a reasonable estimate of the transition tax and recorded a provisional transition tax obligation of $12.0 million. The Company continues to gather additional information to more precisely compute the amount of the transition tax. The SEC staff issued Staff Accounting Bulletin No. 118 (SAB 118), which provides guidance on accounting for the tax effects of the Tax Reform. SAB 118 provides a measurement period that should not extend beyond one year from the Tax Reform enactment date for companies to complete the accounting under ASC 740. In accordance with SAB 118, a company must reflect the income tax effects of those aspects of the Tax Reform for which the accounting under ASC 740 is complete. To the extent that a company’s accounting for certain income tax effects of the Tax Reform is incomplete but it can determine a reasonable estimate, it must record a provisional estimate in the financial statements. If a company cannot determine a provisional estimate to be included in the financial statements, it should continue to apply ASC 740 based on the tax laws that were in effect immediately before the enactment of the Tax Reform. While the Company can make reasonable estimates of the impact of the reduction in corporate rate and the deemed repatriation transition tax, the final impact of the Tax Reform may differ from these estimates, due to, among other things, changes in our interpretations and assumptions, additional guidance that may be issued by taxing authorities, and actions the Company may take. The Tax Reform also establishes new tax laws that will affect the fiscal year ending September 30, 2019, including, but not limited to, (1) elimination of the corporate alternative minimum tax, (2) a new provision designed to tax global intangible low-taxed income (GILTI), (3) limitations on the utilization of net operating losses generated after December 31, 2017 to 80 percent of taxable income per tax year, (4) the creation of the base erosion anti-abuse tax (BEAT), (5) a general elimination of U.S. federal income taxes on dividends from foreign subsidiaries, and (6) limitations on the deductibility of certain executive compensation. Effects of tax law changes where a reasonable estimate of the accounting effects has not yet been made include additional limitations on certain meals and entertainment expenses and the unlimited carryforward of net operating losses. The Company has also not yet determined the potential tax impact of provisions that are not yet effective, such as GILTI, BEAT, elimination of U.S. tax on dividends of future foreign earnings, and a limitation of the utilization of net operating losses generated after fiscal 2018 to 80 percent of taxable income per tax year. The Company expects to make the policy election to treat GILTI as a period expense in the fiscal year ending September 30, 2018. Current and Prior Period Tax Expense Income tax expense of $25.5 million and $2.1 million for the three months ended December 31, 2017 and 2016, respectively, reflect estimated federal, foreign, state and local taxes. The Company recorded discrete expense of $20.9 million related to the Tax Reform. Tax expense, excluding the discrete expense related to the Tax Reform, was $4.6 million. For the three months ended December 31, 2017 and 2016, the Company’s effective tax rate was 137% and 25%, respectively. The discrete expense of $20.9 million related to tax reform, increased the effective tax rate by 112%. The effective rate for the first quarter of 2018 was 24.5%, excluding the impacts of the Tax Reform. The Company’s effective tax rate decreased 1.2% due to excess tax benefits on share-based compensation recognized during the period related to the adoption of ASU 2016-09. See Note 1 for more information regarding the adoption of ASU 2016-09. The effective rate during the first quarter of fiscal year 2017 was lower than the U.S. federal statutory rate primarily due to a higher mix of earnings taxed at lower rates in foreign jurisdictions. The valuation allowance for deferred tax assets as of December 31, 2017 and September 30, 2017 was $4.5 million and $4.0 million, respectively. The valuation allowances as of December 31, 2017 and September 30, 2017 were primarily related to U.S. state and local and foreign net operating loss carryforwards that, in the judgment of management, are not more likely than not to be realized. In assessing the realizability of deferred tax assets, management considers whether it is more likely than not that some or all of the deferred tax assets will not be realized. The Company incurred U.S. federal, state, and local taxable income (losses) for the fiscal years ended September 30, 2017, 2016, and 2015 of $(24.7) million, $(9.7) million and $16.5 million, respectively. The differences between actual levels of past taxable income (losses) and pre-tax book income (losses) are primarily attributable to temporary differences in these jurisdictions. When evaluating if U.S. federal, state, and local deferred tax assets are realizable, the Company considered deferred tax liabilities of $5.5 million that are scheduled to reverse from 2018 to 2020 and $2.3 million of deferred tax liabilities associated with unrealized gains in securities which the Company could sell, if necessary. Furthermore, the Company considered its ability to implement business and tax planning strategies that would allow the remaining U.S. federal, state, and local deferred tax assets, net of valuation allowances, to be realized within approximately 5 years. Based on the tax planning strategies that are prudent and feasible, management believes that it is more likely than not that the Company will realize the tax benefit of the deferred tax assets, net of the existing valuation allowance, in the future. However, the realization of deferred income taxes is dependent on future events, and changes in estimates in future periods could result in adjustments to the valuation allowance. The Company and its subsidiaries file income tax returns with the U.S. federal jurisdiction and various state, local and foreign jurisdictions. The Company has open tax years ranging from September 30, 2010 through September 30, 2017 with U.S. federal and state and local taxing authorities. In the U.K., the Company has open tax years ending September 30, 2016 to September 30, 2017. In Brazil, the Company has open tax years ranging from December 31, 2012 through December 31, 2017. In Argentina, the Company has open tax years ranging from September 30, 2010 to September 30, 2017. In Singapore, the Company has open tax years ranging from September 30, 2012 to September 30, 2017.

Income Taxes

The income tax provision for interim periods is comprised of tax on ordinary income (loss) provided at the most recent estimated annual effective tax rate, adjusted for the tax effect of discrete items. Management uses an estimated annual effective tax rate based on the forecasted pretax income (loss) and statutory tax rates in the various jurisdictions in which it operates. The Company’s effective tax rate differs from the U.S. statutory rate primarily due to state and local taxes, and differing statutory tax rates applied to the income of non-U.S. subsidiaries. The Company records the tax effect of certain discrete items, including the effects of changes in tax laws, tax rates and adjustments with respect to valuation allowances or other unusual or nonrecurring tax adjustments, in the interim period in which they occur, as an addition to, or reduction from, the income tax provision, rather than being included in the estimated effective annual income tax rate. In addition, jurisdictions with a projected loss for the year or a year-to-date loss where no tax benefit can be recognized are excluded from the estimated annual effective income tax rate.

The Company is required to assess its deferred tax assets and the need for a valuation allowance at each reporting period. This assessment requires judgment on the part of management with respect to benefits that may be realized. The Company will record a valuation allowance against deferred tax assets when it is considered more likely than not that all or a portion of the deferred tax assets will not be realized.

Effects of the Tax Cuts and Jobs Act

On December 22, 2017, the President of the United States signed and enacted into law H.R. 1, the Tax Cuts and Jobs Act (“the Tax Reform”). Among the significant changes to the U.S. Internal Revenue Code, the Tax Reform lowers the U.S. federal corporate income tax rate from 35% to 21%, effective January 1, 2018. The Company will compute its income tax expense (benefit) for the September 30, 2018 tax year using a U.S. statutory tax rate of 24.5%. The 21% U.S. statutory tax rate will apply to fiscal years ending September 30, 2019 and thereafter. For the three months ended December 31, 2017, the Company recorded tax expense of $8.9 million related to the remeasurement of deferred tax assets and liabilities. The provisional remeasurement amount is anticipated to change as data becomes available allowing more accurate scheduling of certain deferred tax assets and liabilities. The Tax Reform also includes a one-time mandatory repatriation transition tax on previously untaxed accumulated and current earnings and profits (E&P) of certain of the Company’s foreign subsidiaries. To determine the amount of the transition tax, the Company must determine, in addition to other factors, the amount of post 1986 E&P of the relevant subsidiaries, as well as the amount of non-US income taxes paid on such earnings. The Company made a reasonable estimate of the transition tax and recorded a provisional transition tax obligation of $12.0 million. The Company continues to gather additional information to more precisely compute the amount of the transition tax.

The SEC staff issued Staff Accounting Bulletin No. 118 (SAB 118), which provides guidance on accounting for the tax effects of the Tax Reform. SAB 118 provides a measurement period that should not extend beyond one year from the Tax Reform enactment date for companies to complete the accounting under ASC 740. In accordance with SAB 118, a company must reflect the income tax effects of those aspects of the Tax Reform for which the accounting under ASC 740 is complete. To the extent that a company’s accounting for certain income tax effects of the Tax Reform is incomplete but it can determine a reasonable estimate, it must record a provisional estimate in the financial statements. If a company cannot determine a provisional estimate to be included in the financial statements, it should continue to apply ASC 740 based on the tax laws that were in effect immediately before the enactment of the Tax Reform.

While the Company can make reasonable estimates of the impact of the reduction in corporate rate and the deemed repatriation transition tax, the final impact of the Tax Reform may differ from these estimates, due to, among other things, changes in our interpretations and assumptions, additional guidance that may be issued by taxing authorities, and actions the Company may take.

The Tax Reform also establishes new tax laws that will affect the fiscal year ending September 30, 2019, including, but not limited to, (1) elimination of the corporate alternative minimum tax, (2) a new provision designed to tax global intangible low-taxed income (GILTI), (3) limitations on the utilization of net operating losses generated after December 31, 2017 to 80 percent of taxable income per tax year, (4) the creation of the base erosion anti-abuse tax (BEAT), (5) a general elimination of U.S. federal income taxes on dividends from foreign subsidiaries, and (6) limitations on the deductibility of certain executive compensation.

Effects of tax law changes where a reasonable estimate of the accounting effects has not yet been made include additional limitations on certain meals and entertainment expenses and the unlimited carryforward of net operating losses. The Company has also not yet determined the potential tax impact of provisions that are not yet effective, such as GILTI, BEAT, elimination of U.S. tax on dividends of future foreign earnings, and a limitation of the utilization of net operating losses generated after fiscal 2018 to 80 percent of taxable income per tax year. The Company expects to make the policy election to treat GILTI as a period expense in the fiscal year ending September 30, 2018.

Current and Prior Period Tax Expense

Income tax expense of $25.5 million and $2.1 million for the three months ended December 31, 2017 and 2016, respectively, reflect estimated federal, foreign, state and local taxes. The Company recorded discrete expense of $20.9 million related to the Tax Reform. Tax expense, excluding the discrete expense related to the Tax Reform, was $4.6 million.

For the three months ended December 31, 2017 and 2016, the Company’s effective tax rate was 137% and 25%, respectively. The discrete expense of $20.9 million related to tax reform, increased the effective tax rate by 112%. The effective rate for the first quarter of 2018 was 24.5%, excluding the impacts of the Tax Reform. The Company’s effective tax rate decreased 1.2% due to excess tax benefits on share-based compensation recognized during the period related to the adoption of ASU 2016-09. See Note 1 for more information regarding the adoption of ASU 2016-09. The effective rate during the first quarter of fiscal year 2017 was lower than the U.S. federal statutory rate primarily due to a higher mix of earnings taxed at lower rates in foreign jurisdictions.

The valuation allowance for deferred tax assets as of December 31, 2017 and September 30, 2017 was $4.5 million and $4.0 million, respectively. The valuation allowances as of December 31, 2017 and September 30, 2017 were primarily related to U.S. state and local and foreign net operating loss carryforwards that, in the judgment of management, are not more likely than not to be realized. In assessing the realizability of deferred tax assets, management considers whether it is more likely than not that some or all of the deferred tax assets will not be realized.

The Company incurred U.S. federal, state, and local taxable income (losses) for the fiscal years ended September 30, 2017, 2016, and 2015 of $(24.7) million, $(9.7) million and $16.5 million, respectively. The differences between actual levels of past taxable income (losses) and pre-tax book income (losses) are primarily attributable to temporary differences in these jurisdictions. When evaluating if U.S. federal, state, and local deferred tax assets are realizable, the Company considered deferred tax liabilities of $5.5 million that are scheduled to reverse from 2018 to 2020 and $2.3 million of deferred tax liabilities associated with unrealized gains in securities which the Company could sell, if necessary. Furthermore, the Company considered its ability to implement business and tax planning strategies that would allow the remaining U.S. federal, state, and local deferred tax assets, net of valuation allowances, to be realized within approximately 5 years. Based on the tax planning strategies that are prudent and feasible, management believes that it is more likely than not that the Company will realize the tax benefit of the deferred tax assets, net of the existing valuation allowance, in the future. However, the realization of deferred income taxes is dependent on future events, and changes in estimates in future periods could result in adjustments to the valuation allowance.

The Company and its subsidiaries file income tax returns with the U.S. federal jurisdiction and various state, local and foreign jurisdictions. The Company has open tax years ranging from September 30, 2010 through September 30, 2017 with U.S. federal and state and local taxing authorities. In the U.K., the Company has open tax years ending September 30, 2016 to September 30, 2017. In Brazil, the Company has open tax years ranging from December 31, 2012 through December 31, 2017. In Argentina, the Company has open tax years ranging from September 30, 2010 to September 30, 2017. In Singapore, the Company has open tax years ranging from September 30, 2012 to September 30, 2017.