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Asbestos - Summary of Net Unfunded AFFA Liability, Net of Tax (Detail) $ in Millions, $ in Millions | 12 Months Ended
--- | ---
Mar. 31, 2019 USD ($) | Mar. 31, 2019 AUD ($) | Mar. 31, 2018 USD ($) | Mar. 31, 2017 USD ($)
Asbestos Net Liability [Roll Forward] |  |  |  |
Asbestos Net Liability | $ (983.0) |  | $ (1,094.4) |
Deferred income taxes - Asbestos | 349.3 |  | 382.9 |
Income Tax Payable Asbestos | 25.3 |  | 21.1 |
Net Unfunded AFFA liability, net of tax, Beginning Balance | (690.4) |  |  |
AICF operating costs paid - non claims-handling | (1.5) |  | (1.9) | $ (1.5)
Change in claims handling cost estimate | 1.1 |  | (0.5) | $ 2.1
Net Unfunded AFFA liability, net of tax, Ending Balance | (608.4) |  | (690.4) |
Asbestos Liability |  |  |  |
Asbestos Net Liability [Roll Forward] |  |  |  |
Asbestos Net Liability | (1,089.6) |  | (1,215.1) |
Asbestos claims paid | 107.6 | $ 147.5 |  |
AICF claims-handling costs incurred (paid) | 1.2 |  |  |
Change in actuarial estimate | (73.9) |  |  |
Change in claims handling cost estimate | (1.1) |  |  |
Effect of foreign exchange | (89.5) |  |  |
Insurance Receivables |  |  |  |
Asbestos Net Liability [Roll Forward] |  |  |  |
Asbestos Net Liability | 51.2 |  | 57.9 |
Change in actuarial estimate | 0.0 |  |  |
Insurance recoveries | (2.5) |  |  |
Effect of foreign exchange | (4.2) |  |  |
Restricted Cash and Investments |  |  |  |
Asbestos Net Liability [Roll Forward] |  |  |  |
Asbestos Net Liability | 57.5 |  | 65.0 |
Asbestos claims paid | (107.6) |  |  |
Payment received in accordance with AFFA | 103.0 |  |  |
AICF claims-handling costs incurred (paid) | (1.2) |  |  |
AICF operating costs paid - non claims-handling | (1.5) |  |  |
Insurance recoveries | (4.8) |  |  |
Other movements | 1.6 |  |  |
Effect of foreign exchange | (6.6) |  |  |
Other Assets and Liabilities |  |  |  |
Asbestos Net Liability [Roll Forward] |  |  |  |
Asbestos Net Liability | (2.1) |  | $ (2.2) |
Other movements | 0.0 |  |  |
Effect of foreign exchange | (0.1) |  |  |
Net Unfunded AFFA Liability |  |  |  |
Asbestos Net Liability [Roll Forward] |  |  |  |
Payment received in accordance with AFFA | 103.0 | $ 138.4 |  |
AICF operating costs paid - non claims-handling | (1.5) |  |  |
Change in actuarial estimate | (73.9) |  |  |
Change in claims handling cost estimate | 1.1 |  |  |
Insurance recoveries | 2.3 |  |  |
Other movements | 1.6 |  |  |
Effect of foreign exchange | 78.8 |  |  |
Deferred Tax Assets |  |  |  |
Asbestos Net Liability [Roll Forward] |  |  |  |
Impact on deferred income tax due to change in actuarial estimate | (21.2) |  |  |
Movement in income tax payable | (26.0) |  |  |
Other movements | (0.2) |  |  |
Effect of foreign exchange | (28.6) |  |  |
Income Tax Payable |  |  |  |
Asbestos Net Liability [Roll Forward] |  |  |  |
Movement in income tax payable | (5.2) |  |  |
Other movements | (0.3) |  |  |
Effect of foreign exchange | (0.7) |  |  |
Net Unfunded AFFA Liability, net of tax |  |  |  |
Asbestos Net Liability [Roll Forward] |  |  |  |
Asbestos claims paid | 0.0 |  |  |
Payment received in accordance with AFFA | 103.0 |  |  |
AICF claims-handling costs incurred (paid) | 0.0 |  |  |
AICF operating costs paid - non claims-handling | (1.5) |  |  |
Change in actuarial estimate | (73.9) |  |  |
Change in claims handling cost estimate | 1.1 |  |  |
Impact on deferred income tax due to change in actuarial estimate | 21.2 |  |  |
Insurance recoveries | 2.3 |  |  |
Movement in income tax payable | (20.8) |  |  |
Other movements | 1.1 |  |  |
Effect of foreign exchange | $ 49.5 |  |  |

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