Recent Accounting Standards - Recent Accounting Standards (Policies)	6 Months Ended
Mar. 31, 2018
Accounting Policies [Abstract]
Recent Accounting Standards	Adoption of New Accounting Pronouncement In October 2016, the FASB issued amended guidance that improves the accounting for the income tax consequences of intra-entity transfers of assets other than inventory. Under the new guidance, an entity should recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. The new standard is required to be adopted in the first quarter of our fiscal 2019. We elected to early adopt the amended guidance in the first quarter of fiscal 2018. The effect of adoption is a decrease in our opening retained earnings by $6.1 million with a comparable decrease to our non-current prepaid income tax balance. In March 2016, the FASB issued amended guidance that simplifies several aspects of the accounting for employee share-based payment transactions, including the accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification in the statement of cash flows. Under the new guidance, an entity recognizes all excess tax benefits and tax deficiencies as income tax expense or benefit in the income statement. This change eliminates the notion of the APIC pool and significantly reduces the complexity and cost of accounting for excess tax benefits and tax deficiencies. Upon our adoption in the first quarter of fiscal 2018, we recognized a windfall tax benefit as a cumulative effect adjustment increase to our opening retained earnings of $19.8 million together with a comparable increase in deferred tax assets. With adoption occurring at the beginning of fiscal 2018, we recognized excess tax benefits from stock award exercises and restricted stock unit vesting as a discrete tax benefit which reduced the provision for income taxes for the three and six months ended March 31, 2018 by $0.3 million and $12.8 million, respectively. The adoption also changed the calculation of fully diluted shares outstanding for the three and six months ended March 31, 2018. The excess tax benefits have been excluded from the calculation of assumed proceeds in our calculation of diluted weighted average shares under the new standard. Our diluted weighted average shares outstanding for the three and six months ended March 31, 2018 increased by 74,891 and 99,577 shares, respectively, due to adoption of the new standard. Additionally, effective in the first quarter of fiscal 2018, excess tax benefits are classified as an operating activity in the statement of cash flows instead of as a financing activity where they were previously presented. We adopted this guidance on a prospective basis and, accordingly, prior periods have not been adjusted. We have elected to not estimate forfeitures expected to occur to determine the amount of compensation cost to be recognized in each period. The remaining provisions of this amended guidance did not have a material impact on our consolidated financial statements. Recently Issued Accounting Pronouncements In February 2018, the FASB issued amended guidance to allow a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act. Consequently, the amendments eliminate the stranded tax effects resulting from the Tax Cuts and Jobs Act and will improve the usefulness of information reported to financial statement users. However, because the amendments only relate to the reclassification of the income tax effects of the Tax Cuts and Jobs Act, the underlying guidance that requires that the effect of a change in tax laws or rates be included in income from continuing operations is not affected. The amendments in this Update also require certain disclosures about stranded tax effects. The new standard will become effective for our fiscal year 2020 which begins on September 29, 2019. We are currently assessing the impact of this amended guidance. In August 2017, the FASB issued amended guidance to address the current limitation on how an entity can designate the hedged risk in certain cash flow and fair value hedging relationships pursuant to U.S. GAAP. This amendment better aligns an entity's risk management activities and financial reporting for hedging relationships through changes to both designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results. The amendment made specific improvements on hedge accounting for risk components in hedging relationships involving nonfinancial risk and interest rate risk for cash flow hedges of forecasted purchases or sales of a nonfinancial asset, cash flow hedges of interest rate risk of variable-rate financial instruments and fair value hedges of interest rate risk. Upon adoption, for cash flow and net investment hedges existing, an entity should apply a cumulative-effect adjustment related to eliminating the separate measurement of ineffectiveness to other comprehensive income with a corresponding adjustment to the opening balance of retained earnings as of the beginning of the fiscal year that an entity adopts the amendment. The amended presentation and disclosure guidance is required only prospectively. The new standard will become effective for our fiscal year 2020 which begins on September 29, 2019. We are currently assessing the impact of this amended guidance. In May 2016, accounting guidance was issued to clarify the not yet effective revenue recognition guidance issued in May 2014. This additional guidance does not change the core principle of the revenue recognition guidance issued in May 2014, rather, it provides clarification of accounting for collections of sales taxes as well as recognition of revenue (i) associated with contract modifications, (ii) for non-cash consideration, and (iii) based on the collectability of the consideration from the customer. The guidance also specifies when a contract should be considered “completed” for purposes of applying the transition guidance. The effective date and transition requirements for this guidance are the same as the effective date and transition requirements for the guidance previously issued in 2014, which is effective for our fiscal year 2019 which begins on September 30, 2018. We have elected to not adopt the standard earlier. The guidance permits two methods of adoption: retrospectively to each prior reporting period presented (full retrospective method), or retrospectively with the cumulative effect of initially applying the guidance recognized at the date of initial application (modified retrospective method). We currently anticipate adopting the standard using the full retrospective method. However, our ability to apply the full retrospective method is dependent on the completion of our analysis that is on-going. We have established a cross-functional team to implement the new standard with respect to the recognition of revenue from contracts with customers. Based on our ongoing evaluation, we do not expect a material change to our current revenue recognition practices under the new guidance but such an expectation may change and will be further clarified as we complete our implementation of the new standard. We will continue to assess the new standard along with industry trends and additional interpretive guidance, and may adjust our implementation plan accordingly. In February 2016, the FASB issued amended guidance to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. The new guidance clarifies the criteria for distinguishing between a finance lease and operating lease, as well as classification between the two types of leases, which is substantially unchanged from the previous lease guidance. Further, the new guidance requires a lessee to recognize in the statement of financial position a liability to make lease payments (the lease liability) and a right-of-use asset, initially measured at the present value of the lease payments. For finance leases, a lessee should recognize interest on the lease liability separately from amortization of the right-of-use asset. For operating leases, a lessee should recognize a single lease cost, calculated so that the cost of the lease is allocated over the lease term on a generally straight-line basis. For leases with a term of 12 months or less, a lessee is permitted to make an accounting policy election not to recognize lease assets and lease liabilities. The new standard will become effective for our fiscal year 2020 which begins on September 29, 2019. We are currently assessing the impact of this amended guidance.

Adoption of New Accounting Pronouncement

In October 2016, the FASB issued amended guidance that improves the accounting for the income tax consequences of intra-entity transfers of assets other than inventory. Under the new guidance, an entity should recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. The new standard is required to be adopted in the first quarter of our fiscal 2019. We elected to early adopt the amended guidance in the first quarter of fiscal 2018. The effect of adoption is a decrease in our opening retained earnings by $6.1 million with a comparable decrease to our non-current prepaid income tax balance.

In March 2016, the FASB issued amended guidance that simplifies several aspects of the accounting for employee share-based payment transactions, including the accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification in the statement of cash flows. Under the new guidance, an entity recognizes all excess tax benefits and tax deficiencies as income tax expense or benefit in the income statement. This change eliminates the notion of the APIC pool and significantly reduces the complexity and cost of accounting for excess tax benefits and tax deficiencies. Upon our adoption in the first quarter of fiscal 2018, we recognized a windfall tax benefit as a cumulative effect adjustment increase to our opening retained earnings of $19.8 million together with a comparable increase in deferred tax assets. With adoption occurring at the beginning of fiscal 2018, we recognized excess tax benefits from stock award exercises and restricted stock unit vesting as a discrete tax benefit which reduced the provision for income taxes for the three and six months ended March 31, 2018 by $0.3 million and $12.8 million, respectively. The adoption also changed the calculation of fully diluted shares outstanding for the three and six months ended March 31, 2018. The excess tax benefits have been excluded from the calculation of assumed proceeds in our calculation of diluted weighted average shares under the new standard. Our diluted weighted average shares outstanding for the three and six months ended March 31, 2018 increased by 74,891 and 99,577 shares, respectively, due to adoption of the new standard. Additionally, effective in the first quarter of fiscal 2018, excess tax benefits are classified as an operating activity in the statement of cash flows instead of as a financing activity where they were previously presented. We adopted this guidance on a prospective basis and, accordingly, prior periods have not been adjusted. We have elected to not estimate forfeitures expected to occur to determine the amount of compensation cost to be recognized in each period. The remaining provisions of this amended guidance did not have a material impact on our consolidated financial statements.

Recently Issued Accounting Pronouncements

In February 2018, the FASB issued amended guidance to allow a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act. Consequently, the amendments eliminate the stranded tax effects resulting from the Tax Cuts and Jobs Act and will improve the usefulness of information reported to financial statement users. However, because the amendments only relate to the reclassification of the income tax effects of the Tax Cuts and Jobs Act, the underlying guidance that requires that the effect of a change in tax laws or rates be included in income from continuing operations is not affected. The amendments in this Update also require certain disclosures about stranded tax effects. The new standard will become effective for our fiscal year 2020 which begins on September 29, 2019. We are currently assessing the impact of this amended guidance.

In August 2017, the FASB issued amended guidance to address the current limitation on how an entity can designate the hedged risk in certain cash flow and fair value hedging relationships pursuant to U.S. GAAP. This amendment better aligns an entity's risk management activities and financial reporting for hedging relationships through changes to both designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results. The amendment made specific improvements on hedge accounting for risk components in hedging relationships involving nonfinancial risk and interest rate risk for cash flow hedges of forecasted purchases or sales of a nonfinancial asset, cash flow hedges of interest rate risk of variable-rate financial instruments and fair value hedges of interest rate risk. Upon adoption, for cash flow and net investment hedges existing, an entity should apply a cumulative-effect adjustment related to eliminating the separate measurement of ineffectiveness to other comprehensive income with a corresponding adjustment to the opening balance of retained earnings as of the beginning of the fiscal year that an entity adopts the amendment. The amended presentation and disclosure guidance is required only prospectively. The new standard will become effective for our fiscal year 2020 which begins on September 29, 2019. We are currently assessing the impact of this amended guidance.

In May 2016, accounting guidance was issued to clarify the not yet effective revenue recognition guidance issued in May 2014. This additional guidance does not change the core principle of the revenue recognition guidance issued in May 2014, rather, it provides clarification of accounting for collections of sales taxes as well as recognition of revenue (i) associated with contract modifications, (ii) for non-cash consideration, and (iii) based on the collectability of the consideration from the customer. The guidance also specifies when a contract should be considered “completed” for purposes of applying the transition guidance. The effective date and transition requirements for this guidance are the same as the effective date and transition requirements for the guidance previously issued in 2014, which is effective for our fiscal year 2019 which begins on September 30, 2018. We have elected to not adopt the standard earlier. The guidance permits two methods of adoption: retrospectively to each prior reporting period presented (full retrospective method), or retrospectively with the cumulative effect of initially applying the guidance recognized at the date of initial application (modified retrospective method). We currently anticipate adopting the standard using the full retrospective method. However, our ability to apply the full retrospective method is dependent on the completion of our analysis that is on-going. We have established a cross-functional team to implement the new standard with respect to the recognition of revenue from contracts with customers. Based on our ongoing evaluation, we do not expect a material change to our current revenue recognition practices under the new guidance but such an expectation may change and will be further clarified as we complete our implementation of the new standard. We will continue to assess the new standard along with industry trends and additional interpretive guidance, and may adjust our implementation plan accordingly.

In February 2016, the FASB issued amended guidance to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. The new guidance clarifies the criteria for distinguishing between a finance lease and operating lease, as well as classification between the two types of leases, which is substantially unchanged from the previous lease guidance. Further, the new guidance requires a lessee to recognize in the statement of financial position a liability to make lease payments (the lease liability) and a right-of-use asset, initially measured at the present value of the lease payments. For finance leases, a lessee should recognize interest on the lease liability separately from amortization of the right-of-use asset. For operating leases, a lessee should recognize a single lease cost, calculated so that the cost of the lease is allocated over the lease term on a generally straight-line basis. For leases with a term of 12 months or less, a lessee is permitted to make an accounting policy election not to recognize lease assets and lease liabilities. The new standard will become effective for our fiscal year 2020 which begins on September 29, 2019. We are currently assessing the impact of this amended guidance.