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Business Combinations - Summary of Intangible Assets Acquired (Details) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Mar. 31, 2019 | Mar. 31, 2018 | Apr. 03, 2018
Finite-Lived Intangible Assets [Line Items] |  |  |
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life | 11 years 8 months | 6 years 1 month |
Fermacell |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Intangible assets |  |  | $ 187.0
Trade name [Member] | Fermacell |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Intangible assets |  |  | 126.8
Customer relationships [Member] |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life | 12 years | 0 years |
Customer relationships [Member] | Fermacell |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Intangible assets |  |  | 57.8
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life | 13 years |  |
Other intangible assets [Member] |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life | 7 years 6 months | 6 years 1 month |
Other intangible assets [Member] | Fermacell |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Intangible assets |  |  | $ 2.4
Minimum [Member] |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life | 2 years |  |
Minimum [Member] | Fermacell |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life | 2 years |  |
Maximum [Member] |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life | 13 years |  |
Maximum [Member] | Fermacell |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life | 13 years |  |

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- Definition Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275 + Details
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- Definition Amount of intangible assets, excluding goodwill, acquired at the acquisition date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84161108&loc=d3e4845-128472 + 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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