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Income Taxes - Schedule of Reconciliation of Beginning and Ending Unrecognized Tax Benefits (Detail) - USD ($) $ in Millions | 12 Months Ended
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Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2016
Income Tax Disclosure [Abstract] |  |  |
Unrecognized tax benefits at the beginning of year | $ 25.2 | $ 24.2 | $ 26.3
Gross increases - current year tax positions | 0.6 | 0.7 | 0.6
Gross increases - prior year tax positions | 2.4 | 0.7 | 5.4
Gross decreases - prior year tax positions | (3.3) | (0.4) | (8.1)
Unrecognized tax benefits at end of year | 24.9 | 25.2 | 24.2
Interest and penalties in year-end balance | $ 1.5 | $ (0.9) | $ 0.5

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- Definition Unrecognized Tax Benefits Net Of Federal Benefits On State Income Tax Positions And Interest + References No definition available. + Details
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- Definition Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15A -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=84230637&loc=SL6600010-109319 + Details
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- Definition Amount of expense for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32718-109319 + Details
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- Definition Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15A -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=84230637&loc=SL6600010-109319 + Details
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