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Summary of Significant Accounting Policies (Tables) | 12 Months Ended
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Mar. 31, 2020
Accounting Policies [Abstract] |
Property, Plant and Equipment Estimated Useful Lives | Depreciation of property, plant and equipment is computed using the straight-line method over the following estimated useful lives:
| Years
Buildings | 5 to 50
Buildings Improvements | 3 to 40
Leasehold Improvements | 4 to 40
Machinery and Equipment | 1 to 40
Basic and Dilutive Common Shares Outstanding Used in Determining Net Income Per Share | Basic and dilutive common shares outstanding used in determining net income per share are as follows:
| Years Ended 31 March
(Millions of shares) | 2020 |  | 2019 |  | 2018
Basic common shares outstanding | 442.6 |  |  | 441.9 |  |  | 441.2 |
Dilutive effect of stock awards | 1.5 |  |  | 1.1 |  |  | 1.1 |
Diluted common shares outstanding | 444.1 |  |  | 443.0 |  |  | 442.3 |
(US dollars) | 2020 |  | 2019 |  | 2018
Net income per share - basic | 0.55 |  |  | 0.52 |  |  | 0.33 |
Net income per share - diluted | 0.54 |  |  | 0.52 |  |  | 0.33 |
Schedule of Immaterial Change in Statement of Cash Flows Line Items | The amounts presented within this report in the consolidated statement of cash flows have been adjusted for the fiscal years ended 31 March 2019 and 2018, as set forth in the following table:
| Year Ended 31 March 2019 |  | Year Ended 31 March 2018
(Millions of US dollars) | As reported | As adjusted |  | As reported | As adjusted
Cash Flows From Operating Activities |  |  |  |  |
Accounts payable and accrued liabilities | $ | (12.9 | ) | $ | 3.5 |  |  | $ | 14.2 |  | $ | 20.7 |
Net cash provided by operating activities | 287.6 |  | 304.0 |  |  | 302.0 |  | 308.5 |
Cash Flows From Investing Activities |  |  |  |  |
Purchases of property, plant and equipment | (301.1 | ) | (317.5 | ) |  | (203.7 | ) | (210.2 | )
Net cash used in investing activities | (848.0 | ) | (864.4 | ) |  | (239.0 | ) | (245.5 | )

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- Definition Tabular disclosure of an entity's basic and diluted earnings per share calculations, including a reconciliation of numerators and denominators of the basic and diluted per-share computations for income from continuing operations. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 + Details
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- Definition Tabular disclosure of prior period adjustments to previously issued financial statements including (1) the effect of the correction on each financial statement line item and any per-share amounts affected for each prior period presented (2) the cumulative effect of the change on retained earnings or other appropriate components of equity or net assets in the statement of financial position, as of the beginning of the earliest period presented, and (3) the effect of the prior period adjustments (both gross and net of applicable income tax) on the net income of each prior period presented in the entity's annual report for the year in which the adjustments are made. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 9 -URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22663-107794 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22644-107794 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22658-107794 + Details
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