Stock-Based Compensation - Assumptions Used for Restricted Stock Grants (Detail) - Restricted Stock Units (Market Condition) [Member] - $ / shares |
12 Months Ended | |
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Mar. 31, 2018 |
Mar. 31, 2017 |
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||
| Date of grant | Aug. 21, 2017 | Sep. 16, 2016 |
| Dividend yield (per annum) | 3.00% | 2.30% |
| Expected volatility | 30.10% | 31.50% |
| Risk free interest rate | 1.50% | 1.10% |
| Expected life in years | 3 years 3 months 24 days | 3 years |
| JHX stock price at grant date (A$ per share)) | $ 17.91 | $ 20.82 |
| Number of restricted stock units (in shares) | 932,393 | 456,819 |
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- Definition Share based compensation arrangement by share based payment award fair value assumptions date of grant. No definition available.
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- Definition Share based compensation arrangement by share based payment award fair value assumptions grant date stock price. No definition available.
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- Definition Share based compensation arrangement by share based payment award restricted stock units number. No definition available.
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- Definition The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition The risk-free interest rate assumption that is used in valuing an option on its own shares. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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. No definition available.
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- Definition Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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