Income Taxes	6 Months Ended
Mar. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The effective tax rates for the first half of fiscal 2019 and 2018 were (0.8)% and 11.0%, respectively. The tax rates for fiscal 2019 and 2018 reflect the impact of the comprehensive tax legislation enacted by the U.S. government on December 22, 2017, which is commonly referred to as the Tax Cuts and Jobs Act ("TCJA"). The TCJA significantly revised the U.S. corporate income tax regime by, among other things, lowering the U.S. corporate tax rate from 35% to 21% effective January 1, 2018, while also repealing the deduction for domestic production activities, limiting the deductibility of certain executive compensation, and implementing a modified territorial tax system with the introduction of the Global Intangible Low-Taxed Income (“GILTI”) tax rules. The TCJA also imposes a one-time transition tax on deemed repatriation of historical earnings of foreign subsidiaries. Based on our analysis of tax earnings and profits and tax deficits at the prescribed measurement dates, we have a cumulative net tax deficit and do not have any tax liability related to this tax. As we have a September 30 fiscal year-end, our U.S. federal corporate income tax rate was blended in fiscal 2018, resulting in a statutory federal rate of approximately 24.5% (3 months at 35% and 9 months at 21%), and will be 21% for fiscal 2019 and subsequent fiscal years. U.S. GAAP requires that the impact of tax legislation be recognized in the period in which the tax law was enacted. As a result of the TCJA, we reduced our deferred tax liabilities and recorded a one-time deferred tax benefit of approximately $10.1 million in the first quarter of fiscal 2018 to reflect our estimate of temporary differences in the United States that would be recovered or settled in fiscal 2018 based on the 24.5% blended corporate tax rate or based on the 21% tax rate in fiscal 2019 and beyond versus the previous enacted 35% corporate tax rate. We finalized this analysis in the first quarter of fiscal 2019 and recorded an additional deferred tax benefit of $2.6 million. Valuation allowances of $22.3 million in Australia were released due to sufficient positive evidence obtained during the second quarter of fiscal 2019. The valuation allowances are primarily related to net operating loss and R&D credit carryforwards and other temporary differences. We evaluated the positive evidence against any negative evidence and determined that it is more likely than not that the deferred tax assets will be realized. The factors used to assess the likelihood of realization were the past performance of the related entities, our forecast of future taxable income, and available tax planning strategies that could be implemented to realize the deferred tax assets. Excluding the net deferred tax benefits from the TCJA and valuation allowance releases, our effective tax rate in the first half of fiscal 2019 was 24.8% compared to 23.0% in first half of fiscal 2018. We have completed our measurement of the tax effects of the TCJA with respect to the one-time revaluation of our deferred tax liabilities and the one-time transition tax on foreign earnings pursuant to Staff Accounting Bulletin No. 118 in the first quarter of fiscal 2019. The amounts recorded for these two items incorporate assumptions made based on our current interpretation of the TCJA and should not materially change. With respect to the GILTI provisions of the TCJA, we have analyzed our structure and expected global results of operations and do not expect to have any adjustment related to potential GILTI tax in our consolidated financial statements. Because of the complexity of the new GILTI tax rules, we will continue to evaluate the impact of this provision and the application of Accounting Standards Codification 740, Income Taxes. As of March 31, 2019 and September 30, 2018, the liability for income taxes associated with uncertain tax positions was $12.1 million and $9.4 million, respectively. These uncertain tax positions substantially relate to ongoing examinations, which are reasonably likely to be resolved within the next 12 months.

Income Taxes

The effective tax rates for the first half of fiscal 2019 and 2018 were (0.8)% and 11.0%, respectively. The tax rates for fiscal 2019 and 2018 reflect the impact of the comprehensive tax legislation enacted by the U.S. government on December 22, 2017, which is commonly referred to as the Tax Cuts and Jobs Act ("TCJA"). The TCJA significantly revised the U.S. corporate income tax regime by, among other things, lowering the U.S. corporate tax rate from 35% to 21% effective January 1, 2018, while also repealing the deduction for domestic production activities, limiting the deductibility of certain executive compensation, and implementing a modified territorial tax system with the introduction of the Global Intangible Low-Taxed Income (“GILTI”) tax rules. The TCJA also imposes a one-time transition tax on deemed repatriation of historical earnings of foreign subsidiaries. Based on our analysis of tax earnings and profits and tax deficits at the prescribed measurement dates, we have a cumulative net tax deficit and do not have any tax liability related to this tax. As we have a September 30 fiscal year-end, our U.S. federal corporate income tax rate was blended in fiscal 2018, resulting in a statutory federal rate of approximately 24.5% (3 months at 35% and 9 months at 21%), and will be 21% for fiscal 2019 and subsequent fiscal years.

U.S. GAAP requires that the impact of tax legislation be recognized in the period in which the tax law was enacted. As a result of the TCJA, we reduced our deferred tax liabilities and recorded a one-time deferred tax benefit of approximately $10.1 million in the first quarter of fiscal 2018 to reflect our estimate of temporary differences in the United States that would be recovered or settled in fiscal 2018 based on the 24.5% blended corporate tax rate or based on the 21% tax rate in fiscal 2019 and beyond versus the previous enacted 35% corporate tax rate. We finalized this analysis in the first quarter of fiscal 2019 and recorded an additional deferred tax benefit of $2.6 million.

Valuation allowances of $22.3 million in Australia were released due to sufficient positive evidence obtained during the second quarter of fiscal 2019. The valuation allowances are primarily related to net operating loss and R&D credit carryforwards and other temporary differences. We evaluated the positive evidence against any negative evidence and determined that it is more likely than not that the deferred tax assets will be realized. The factors used to assess the likelihood of realization were the past performance of the related entities, our forecast of future taxable income, and available tax planning strategies that could be implemented to realize the deferred tax assets. Excluding the net deferred tax benefits from the TCJA and valuation allowance releases, our effective tax rate in the first half of fiscal 2019 was 24.8% compared to 23.0% in first half of fiscal 2018.

We have completed our measurement of the tax effects of the TCJA with respect to the one-time revaluation of our deferred tax liabilities and the one-time transition tax on foreign earnings pursuant to Staff Accounting Bulletin No. 118 in the first quarter of fiscal 2019. The amounts recorded for these two items incorporate assumptions made based on our current interpretation of the TCJA and should not materially change.

With respect to the GILTI provisions of the TCJA, we have analyzed our structure and expected global results of operations and do not expect to have any adjustment related to potential GILTI tax in our consolidated financial statements. Because of the complexity of the new GILTI tax rules, we will continue to evaluate the impact of this provision and the application of Accounting Standards Codification 740, Income Taxes.

As of March 31, 2019 and September 30, 2018, the liability for income taxes associated with uncertain tax positions was $12.1 million and $9.4 million, respectively. These uncertain tax positions substantially relate to ongoing examinations, which are reasonably likely to be resolved within the next 12 months.