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Debt - Schedule of Contractual Interest Expense and Amortization of Discount on Notes (Detail) - USD ($) $ in Millions | 3 Months Ended
--- | ---
Sep. 30, 2018 | Sep. 30, 2017
Debt Instrument [Line Items] |  |
Amortization of discount and debt issuance costs | $ 4.4 | $ 4.3
0.50% Convertible Senior Notes due 2022 [Member] |  |
Debt Instrument [Line Items] |  |
Interest expense | 0.7 |
Amortization of discount and debt issuance costs | 4.4 |
Total interest | $ 5.1 |

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- Definition Amount of amortization expense attributable to debt discount (premium) and debt issuance costs. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399 + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition Amount of the cost of borrowed funds accounted for as interest expense for debt. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6036836-161870 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.8) -URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227 + Details
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- Definition Represents the portion of interest incurred in the period on debt arrangements that was charged against earnings, excluding amortization of debt discount (premium) and financing costs. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph 8 -URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227 + Details
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- Details
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