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Income Taxes - Reconciliation of Unrecognized Tax Benefits and Interest and Penalties (Detail) - USD ($) $ in Millions | 12 Months Ended
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Mar. 31, 2016 | Mar. 31, 2015 | Mar. 31, 2014
Income Tax Disclosure [Abstract] |  |  |
Unrecognized tax benefits, Beginning balance | $ 4.9 | $ 0.5 | $ 1.5
Unrecognized tax benefits, Additions for tax positions of the current year | 0.2 | 4.2 | 0.1
Unrecognized tax benefits, Additions for tax positions of prior year |  | 0.2 | 0.1
Unrecognized tax benefits, Reductions in tax positions of prior year | (4.1) |  |
Unrecognized tax benefits, Settlements paid during the current period | (0.3) |  | (1.2)
Unrecognized tax benefits, Other reductions for the tax positions of prior periods |  |  | 0.0
Unrecognized tax benefits, Ending Balance | 0.7 | 4.9 | 0.5
Interest and Penalties, Beginning balance | 0.3 |  | 0.1
Interest and Penalties, Additions for tax positions of the current year |  | 0.1 |
Interest and Penalties, Additions for tax positions of prior year |  | 0.2 |
Interest and Penalties, Reductions in tax positions of prior year | (0.3) |  |
Interest and Penalties, Settlements paid during the current period | $ 0.0 |  | 0.0
Interest and Penalties, Other reductions for the tax positions of prior periods |  |  | $ (0.1)
Interest and Penalties, Ending Balance |  | $ 0.3 |

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- Definition Unrecognized tax benefits other decreases resulting from prior period tax positions. + References No definition available. + Details
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- Definition Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15A -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6907707&loc=SL6600010-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Unrecognized Tax Benefit -URI http://asc.fasb.org/extlink&oid=6527854 + Details
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- Definition Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15A -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6907707&loc=SL6600010-109319 + Details
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- Definition Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15A -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=6907707&loc=SL6600010-109319 + Details
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- Definition Amount accrued for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32718-109319 + Details
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- Definition Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15A -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=6907707&loc=SL6600010-109319 + Details
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