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Asbestos - Summary of Net Unfunded AFFA Liability, Net of Tax 2 (Detail) $ in Millions, $ in Millions |  | 12 Months Ended | 60 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Jul. 01, 2020 USD ($) | Mar. 31, 2020 USD ($) | Mar. 31, 2020 AUD ($) | Mar. 31, 2019 USD ($) | Mar. 31, 2019 AUD ($) | Mar. 31, 2018 USD ($) | Mar. 31, 2018 AUD ($) | Mar. 31, 2020 USD ($) | Mar. 31, 2020 AUD ($) | Mar. 31, 2020 AUD ($) | Jul. 31, 2019 AUD ($) | Mar. 31, 2019 AUD ($) | Jul. 01, 2018 AUD ($)
Asbestos Claims [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Translation of payments at exchange rate, number of days prior to payment date |  | 5 days | 5 days |  |  |  |  |  |  |  |  |  |
Payment to fund |  | $ 108.9 | $ 156.7 | $ 103.0 | $ 138.4 | $ 102.2 | $ 135.1 | $ 468.0 | $ 632.0 |  |  |  |
Net cash provided by operating activities |  | 451.2 |  | 304.0 |  | $ 308.5 |  |  |  |  |  |  |
Adjustment to Net Cash Provided by (Used in) Operating Activities |  | 13.2 |  |  |  |  |  |  |  |  |  |  |
Restricted short-term investments - Asbestos |  | 21.6 |  | $ 17.7 |  |  |  | $ 21.6 |  | $ 35.0 | $ 110.0 | $ 25.0 | $ 120.0
Restricted Short-Term Investments Asbestos Matured |  |  | 75.0 |  | $ 95.0 |  |  |  |  |  |  |  |
Asbestos Liability |  |  |  |  |  |  |  |  |  |  |  |  |
Asbestos Claims [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Asbestos claims paid |  | 104.6 | 153.3 |  |  |  |  |  |  |  |  |  |
Net Unfunded AFFA Liability |  |  |  |  |  |  |  |  |  |  |  |  |
Asbestos Claims [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Payment received in accordance with AFFA |  | 108.9 | $ 156.7 |  |  |  |  |  |  |  |  |  |
AICF Funding |  |  |  |  |  |  |  |  |  |  |  |  |
Asbestos Claims [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum percentage of Free Cash Flow contributed to AICF (as percent) |  |  |  | 35.00% | 35.00% |  |  |  |  |  |  |  |
Net cash provided by operating activities |  | $ 438.0 |  |  |  |  |  |  |  |  |  |  |
Scenario, Forecast [Member] | AICF Funding |  |  |  |  |  |  |  |  |  |  |  |  |
Asbestos Claims [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Payment to fund | $ 153.3 |  |  |  |  |  |  |  |  |  |  |  |

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