XML 128 R91.htm IDEA: XBRL DOCUMENT
v3.19.1

Capital Management and Dividends - Summary of Dividends Paid (Detail) - USD ($) $ / shares in Units, $ in Millions | 12 Months Ended
--- | ---
Mar. 31, 2019 | Mar. 31, 2018 | Mar. 31, 2017
Dividends Payable [Line Items] |  |  |
Dividend, Total Amount | $ 172.1 | $ 177.5 | $ 176.8
Dividend, Record Date |  | Jun. 06, 2019 |
Dividend, Payment Date |  | Aug. 02, 2019 |
FY 2019 first half dividend |  |  |
Dividends Payable [Line Items] |  |  |
Interim ordinary dividend to shareholders (in dollars per share) | $ 0.10 |  |
Dividend, Total Amount | $ 43.6 |  |
Dividend, Announcement Date | Nov. 08, 2018 |  |
Dividend, Record Date | Dec. 12, 2018 |  |
Dividend, Payment Date | Feb. 22, 2019 |  |
FY 2018 second half dividend |  |  |
Dividends Payable [Line Items] |  |  |
Interim ordinary dividend to shareholders (in dollars per share) | $ 0.30 |  |
Dividend, Total Amount | $ 128.5 |  |
Dividend, Announcement Date | May 22, 2018 |  |
Dividend, Record Date | Jun. 07, 2018 |  |
Dividend, Payment Date | Aug. 03, 2018 |  |
FY 2018 first half dividend |  |  |
Dividends Payable [Line Items] |  |  |
Interim ordinary dividend to shareholders (in dollars per share) | $ 0.10 |  |
Dividend, Total Amount | $ 46.2 |  |
Dividend, Announcement Date | Nov. 09, 2017 |  |
Dividend, Record Date | Dec. 13, 2017 |  |
Dividend, Payment Date | Feb. 23, 2018 |  |
FY 2017 second half dividend |  |  |
Dividends Payable [Line Items] |  |  |
Interim ordinary dividend to shareholders (in dollars per share) | $ 0.28 |  |
Dividend, Total Amount | $ 131.3 |  |
Dividend, Announcement Date | May 18, 2017 |  |
Dividend, Record Date | Jun. 08, 2017 |  |
Dividend, Payment Date | Aug. 04, 2017 |  |
FY 2017 first half dividend |  |  |
Dividends Payable [Line Items] |  |  |
Interim ordinary dividend to shareholders (in dollars per share) | $ 0.10 |  |
Dividend, Total Amount | $ 46.6 |  |
Dividend, Announcement Date | Nov. 17, 2016 |  |
Dividend, Record Date | Dec. 21, 2016 |  |
Dividend, Payment Date | Feb. 24, 2017 |  |
FY 2016 second half dividend |  |  |
Dividends Payable [Line Items] |  |  |
Interim ordinary dividend to shareholders (in dollars per share) | $ 0.29 |  |
Dividend, Total Amount | $ 130.2 |  |
Dividend, Announcement Date | May 19, 2016 |  |
Dividend, Record Date | Jun. 09, 2016 |  |
Dividend, Payment Date | Aug. 05, 2016 |  |

X
- Definition Aggregate dividends paid during the period for each share of common stock outstanding. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 + Details
Name: | us-gaap_CommonStockDividendsPerShareCashPaid
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Date the declared dividend will be paid, in CCYY-MM-DD format. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586 + Details
Name: | us-gaap_DividendPayableDateToBePaidDayMonthAndYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Date the dividend to be paid was declared, in CCYY-MM-DD format. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586 + Details
Name: | us-gaap_DividendsPayableDateDeclaredDayMonthAndYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Date the holder must own the stock to be entitled to the dividend, in CCYY-MM-DD format. + References No definition available. + Details
Name: | us-gaap_DividendsPayableDateOfRecordDayMonthAndYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

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
Name: | us-gaap_DividendsPayableLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of cash outflow in the form of ordinary dividends to common shareholders of the parent entity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3291-108585 + Details
Name: | us-gaap_PaymentsOfDividendsCommonStock
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_DividendsAxis=jhx_FiscalYearTwoThousandAndNineteenFirstHalfDividendMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DividendsAxis=jhx_FiscalYearTwoThousandAndEighteenSecondHalfDividendMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DividendsAxis=jhx_FiscalYearTwoThousandAndEighteenFirstHalfDividendMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DividendsAxis=jhx_FiscalYearTwoThousandAndSeventeenSecondHalfDividendMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DividendsAxis=jhx_FiscalYearTwoThousandAndSeventeenFirstHalfDividendMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DividendsAxis=jhx_FiscalYearTwoThousandAndSixteenSecondHalfDividendMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |