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Summary of Significant Accounting Policies - Additional Information (Detail) shares in Millions, $ in Millions | 12 Months Ended
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Mar. 31, 2017 Directors shares | Mar. 31, 2016 USD ($) shares | Mar. 31, 2015 shares
Summary Of Significant Accounting Policies [Line Items] |  |  |
Ownership interest rate percentage | 100.00% |  |
Number of directors appointed by Company | Directors | 3 |  |
Number of Directors appointed by NSW Government | Directors | 2 |  |
Equity awards vested percentage after first year | 25.00% |  |
Equity awards vested percentage after second year | 25.00% |  |
Equity awards vested percentage after third year | 50.00% |  |
Potential diluted common shares outstanding | shares | 1.8 | 1.3 | 1.7
ASU No. 2015-03 [Member] | Prepaid Expenses and Other Current Assets [Member] |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Debt issuance cost | $ |  | $ 1.6 |
ASU No. 2015-03 [Member] | Other Assets [Member] |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Debt issuance cost | $ |  | $ 9.4 |
AICF Funding [Member] |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |
Ownership interest rate percentage | 0.00% |  |

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- Definition Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Antidilution -URI http://asc.fasb.org/extlink&oid=6505113 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Diluted Earnings Per Share -URI http://asc.fasb.org/extlink&oid=6510752 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Contingent Stock Agreement -URI http://asc.fasb.org/extlink&oid=6508534 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 + Details
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