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Income Taxes - Additional Information (Detail) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2019 | Sep. 30, 2018 | Jun. 30, 2019
Income Tax Disclosure [Line Items] |  |  |
Provision/(benefit) for income taxes | $ (4.9) | $ (0.3) |
Gross unrecognized tax benefits | 20.1 |  | $ 18.9
Gross unrecognized tax benefits increased (decreased) during the year | 1.2 |  |
Interest and penalties accrued related to unrecognized tax benefits | 1.7 |  |
Increase (decrease) in interest and penalties accrued related to unrecognized tax benefits |  |  | $ (0.2)
Maximum [Member] |  |  |
Income Tax Disclosure [Line Items] |  |  |
Estimated increase in unrecognized tax benefit in next twelve months | $ 2.5 |  |

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- Definition Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 22 -Subparagraph (h) -URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(h)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 20 -Section 45 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109238882&loc=d3e38679-109324 + Details
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