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Operating Segment Information and Concentrations of Risk - Summary of Gross Sales by Major Customers (Detail) - Customer A [Member] - USA & Europe Fiber Cement [Member] - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Segment Reporting Information [Line Items]
Gross Sales of Major Customers	$ 197.0	$ 177.4	$ 174.2
Gross sales percentage	10.10%	10.70%	11.70%

X

- Definition

Gross sales of the Company's major customers that individually account for over 10% of the Company's net sales in one or all of the past three fiscal years.

+ References

No definition available.

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- Definition

Major customer percentage of the Company's total gross sales.

+ References

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X

- 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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- Details

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X

- Details

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