Income Taxes	6 Months Ended
Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes At the end of each interim period, we estimate a base effective tax rate that we expect for the full fiscal year based on our most recent forecast of pre-tax income, permanent book and tax differences and global tax planning strategies. We use this base rate to provide for income taxes on a year-to-date basis, excluding the effect of significant unusual items and items that are reported net of their related tax effects in the period in which they occur. Our base rate reflects a change in the U.S. federal statutory rate from 35 percent to 21 percent resulting from the enactment of the Tax Cuts and Jobs Act of 2017 (the “Tax Act”) on December 22, 2017. The rate change was effective for us at the beginning of our fiscal year, using a blended rate for the annual period. As a result, the blended statutory tax rate for our fiscal year 2018 is 24.53 percent. The effective tax rate was 24.1 percent and 101.5 percent in the three and six months ended March 31, 2018, respectively, compared to 17.7 percent and 17.2 percent in the three and six months ended March 31, 2017, respectively. The effective tax rate was lower than the U.S. statutory rate of 24.53 percent in the three months ended March 31, 2018 primarily because we benefited from lower non-U.S. tax rates, partially offset by provisional tax charges ($11.5 million or 3.8 percent) resulting from the Tax Act which are discussed below. The effective rate was higher than the U.S. statutory rate of 24.53 percent in the six months ended March 31, 2018 due to provisional tax charges ($491.2 million or 81.8 percent) resulting from the Tax Act. The effective tax rate was lower than the U.S. statutory rate of 35 percent in the three and six months ended March 31, 2017, primarily because we benefited from lower non-U.S. tax rates, and we also realized a benefit from discrete tax items. Provisional Amounts The Tax Act requires us to revalue our existing U.S. deferred tax balance to reflect the lower statutory tax rate and pay a one-time tax on earnings of certain foreign subsidiaries that were previously deferred from U.S. tax ("transition tax"). At March 31, 2018, we have not completed our accounting for the tax effects of the Tax Act; however, we have made reasonable estimates of its effects on our existing U.S. deferred tax balance and the transition tax and recorded provisional amounts which are included as a component of income tax expense from continuing operations, as discussed in more detail below. We revalued our U.S. deferred tax assets and liabilities based on the rate at which they are expected to reverse in the future, which is either 24.53 percent for reversals in 2018 or 21 percent for reversals in 2019 and subsequent years. However, we are still analyzing certain aspects of the Tax Act and refining our calculations, which could potentially affect the valuation of these balances or potentially give rise to new deferred tax amounts. We have recorded a provisional amount of $94.2 million in the six months ended March 31, 2018, of which the entire amount was recorded in the three months ended December 31, 2017. The Tax Act requires the transition tax to be computed based on our total post-1986 earnings and profits (“E&P”) at December 31, 2017, that were previously deferred from U.S. income tax. As a result, we are required to make reasonable estimates given our September 30 fiscal year. We have recorded provisional amounts of $11.5 million and $397.0 million for the transition tax liability for all of our foreign subsidiaries in the three and six months ended March 31, 2018, respectively. At March 31, 2018, we have recorded income taxes payable of $397.0 million related to the transition tax in the Condensed Consolidated Balance Sheet, of which $34.7 million is recorded within other current liabilities, and $362.3 million is recorded within other liabilities because that portion is payable greater than twelve months from March 31, 2018. 12. Income Taxes (continued) The transition tax is applied to the balance of post-1986 E&P at rates of 15.5 percent for cash assets (as defined in the Tax Act) and 8 percent for non-cash assets measured at the higher of the balance at September 30, 2018 or the average of the ending balances at September 30, 2016, and September 30, 2017. Our reasonable estimates will change as a result of adjustments impacting E&P, and distributions and other transactions impacting cash. The Company anticipates that it will complete its accounting for the transition tax at December 31, 2018. These uncertainties form the basis for the Company’s provisional reporting based upon reasonable estimates at March 31, 2018. The Company has historically accounted for the earnings of its foreign subsidiaries as being indefinitely reinvested under ASC 740-30. As a result of the broad changes to the U.S. international tax system under the Tax Act, the Company will begin to account for substantially all of its non-U.S. subsidiaries as being immediately subject to tax other than in certain limited circumstances. The Company has provided for taxes on the balance of historic and current earnings that may be subject to foreign withholding and U.S. state taxes. For future distributions related to historic earnings, we recorded deferred tax liabilities of $59.8 million related to foreign withholding taxes, and deferred tax assets of $59.8 million related to foreign tax credits attributable to the foreign withholding taxes. These provisional amounts are presented net within deferred income tax assets in the Condensed Consolidated Balance Sheet as of March 31, 2018. We have not yet completed our assessment of whether a portion of these assets and liabilities should be presented as gross amounts. Unrecognized Tax Benefits The amount of gross unrecognized tax benefits was $28.2 million and $31.1 million at March 31, 2018, and September 30, 2017, respectively, of which the entire amount would reduce our effective tax rate if recognized. Accrued interest and penalties related to unrecognized tax benefits were $4.1 million and $4.0 million at March 31, 2018, and September 30, 2017, respectively. We recognize interest and penalties related to unrecognized tax benefits in the income tax provision. We believe it is reasonably possible that the amount of gross unrecognized tax benefits could be reduced by up to $7.4 million in the next 12 months as a result of the resolution of tax matters in various global jurisdictions and the lapses of statutes of limitations. If all of the unrecognized tax benefits were recognized, the net reduction to our income tax provision, including the recognition of interest and penalties and offsetting tax assets, could be up to $8.5 million. We conduct business globally and are routinely audited by the various tax jurisdictions in which we operate. We are no longer subject to U.S. federal income tax examinations for years before 2014 and are no longer subject to state, local and foreign income tax examinations for years before 2003.

Income Taxes

At the end of each interim period, we estimate a base effective tax rate that we expect for the full fiscal year based on our most recent forecast of pre-tax income, permanent book and tax differences and global tax planning strategies. We use this base rate to provide for income taxes on a year-to-date basis, excluding the effect of significant unusual items and items that are reported net of their related tax effects in the period in which they occur.

Our base rate reflects a change in the U.S. federal statutory rate from 35 percent to 21 percent resulting from the enactment of the Tax Cuts and Jobs Act of 2017 (the “Tax Act”) on December 22, 2017. The rate change was effective for us at the beginning of our fiscal year, using a blended rate for the annual period. As a result, the blended statutory tax rate for our fiscal year 2018 is 24.53 percent.

The effective tax rate was 24.1 percent and 101.5 percent in the three and six months ended March 31, 2018, respectively, compared to 17.7 percent and 17.2 percent in the three and six months ended March 31, 2017, respectively. The effective tax rate was lower than the U.S. statutory rate of 24.53 percent in the three months ended March 31, 2018 primarily because we benefited from lower non-U.S. tax rates, partially offset by provisional tax charges ($11.5 million or 3.8 percent) resulting from the Tax Act which are discussed below. The effective rate was higher than the U.S. statutory rate of 24.53 percent in the six months ended March 31, 2018 due to provisional tax charges ($491.2 million or 81.8 percent) resulting from the Tax Act. The effective tax rate was lower than the U.S. statutory rate of 35 percent in the three and six months ended March 31, 2017, primarily because we benefited from lower non-U.S. tax rates, and we also realized a benefit from discrete tax items.

Provisional Amounts

The Tax Act requires us to revalue our existing U.S. deferred tax balance to reflect the lower statutory tax rate and pay a one-time tax on earnings of certain foreign subsidiaries that were previously deferred from U.S. tax ("transition tax"). At March 31, 2018, we have not completed our accounting for the tax effects of the Tax Act; however, we have made reasonable estimates of its effects on our existing U.S. deferred tax balance and the transition tax and recorded provisional amounts which are included as a component of income tax expense from continuing operations, as discussed in more detail below.

We revalued our U.S. deferred tax assets and liabilities based on the rate at which they are expected to reverse in the future, which is either 24.53 percent for reversals in 2018 or 21 percent for reversals in 2019 and subsequent years. However, we are still analyzing certain aspects of the Tax Act and refining our calculations, which could potentially affect the valuation of these balances or potentially give rise to new deferred tax amounts. We have recorded a provisional amount of $94.2 million in the six months ended March 31, 2018, of which the entire amount was recorded in the three months ended December 31, 2017.

The Tax Act requires the transition tax to be computed based on our total post-1986 earnings and profits (“E&P”) at December 31, 2017, that were previously deferred from U.S. income tax. As a result, we are required to make reasonable estimates given our September 30 fiscal year. We have recorded provisional amounts of $11.5 million and $397.0 million for the transition tax liability for all of our foreign subsidiaries in the three and six months ended March 31, 2018, respectively. At March 31, 2018, we have recorded income taxes payable of $397.0 million related to the transition tax in the Condensed Consolidated Balance Sheet, of which $34.7 million is recorded within other current liabilities, and $362.3 million is recorded within other liabilities because that portion is payable greater than twelve months from March 31, 2018.

12. Income Taxes (continued)

The transition tax is applied to the balance of post-1986 E&P at rates of 15.5 percent for cash assets (as defined in the Tax Act) and 8 percent for non-cash assets measured at the higher of the balance at September 30, 2018 or the average of the ending balances at September 30, 2016, and September 30, 2017. Our reasonable estimates will change as a result of adjustments impacting E&P, and distributions and other transactions impacting cash. The Company anticipates that it will complete its accounting for the transition tax at December 31, 2018. These uncertainties form the basis for the Company’s provisional reporting based upon reasonable estimates at March 31, 2018.

The Company has historically accounted for the earnings of its foreign subsidiaries as being indefinitely reinvested under ASC 740-30. As a result of the broad changes to the U.S. international tax system under the Tax Act, the Company will begin to account for substantially all of its non-U.S. subsidiaries as being immediately subject to tax other than in certain limited circumstances. The Company has provided for taxes on the balance of historic and current earnings that may be subject to foreign withholding and U.S. state taxes. For future distributions related to historic earnings, we recorded deferred tax liabilities of $59.8 million related to foreign withholding taxes, and deferred tax assets of $59.8 million related to foreign tax credits attributable to the foreign withholding taxes. These provisional amounts are presented net within deferred income tax assets in the Condensed Consolidated Balance Sheet as of March 31, 2018. We have not yet completed our assessment of whether a portion of these assets and liabilities should be presented as gross amounts.

Unrecognized Tax Benefits

The amount of gross unrecognized tax benefits was $28.2 million and $31.1 million at March 31, 2018, and September 30, 2017, respectively, of which the entire amount would reduce our effective tax rate if recognized.

Accrued interest and penalties related to unrecognized tax benefits were $4.1 million and $4.0 million at March 31, 2018, and September 30, 2017, respectively. We recognize interest and penalties related to unrecognized tax benefits in the income tax provision.

We believe it is reasonably possible that the amount of gross unrecognized tax benefits could be reduced by up to $7.4 million in the next 12 months as a result of the resolution of tax matters in various global jurisdictions and the lapses of statutes of limitations. If all of the unrecognized tax benefits were recognized, the net reduction to our income tax provision, including the recognition of interest and penalties and offsetting tax assets, could be up to $8.5 million.

We conduct business globally and are routinely audited by the various tax jurisdictions in which we operate. We are no longer subject to U.S. federal income tax examinations for years before 2014 and are no longer subject to state, local and foreign income tax examinations for years before 2003.