Income Taxes (Unrecognized Tax Benefits (Excluding Interest And Penalties)) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011
Income Tax Disclosure [Abstract]
Beginning of year	$ 56.8	$ 55.8	$ 106.4
Increases related to current year tax positions	3.6	3.1	6.6
Increases related to prior year tax positions	2.2	8.8	20.8
Decreases related to prior year tax positions	(7.0)	(8.1)	(58.9)
Decreases related to lapses of statutes of limitations	(0.6)	(2.6)	(19.0)
Impact of foreign currency exchange rate changes	(0.1)	(0.2)	(0.1)
End of year	$ 54.9	$ 56.8	$ 55.8

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Amount of income tax benefit or expense because of the current period translation adjustment resulting from translating foreign currency financial statements into the reporting currency.

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The gross amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns as of the balance sheet date.

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The gross amount of decreases in unrecognized tax benefits resulting from tax positions taken in prior period tax returns, excluding amounts pertaining to examined tax returns.

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The gross amount of increases in unrecognized tax benefits resulting from tax positions that have been or will be taken in the tax return for the current period, excluding amounts pertaining to examined tax returns.

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The gross amount of increases in unrecognized tax benefits resulting from tax positions taken in prior period tax returns, excluding amounts pertaining to examined tax returns.

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The gross amount of decreases in unrecognized tax benefits resulting from lapses of the applicable statutes of limitations.

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