Income Taxes (Narrative) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Jun. 30, 2011	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2010
Income Tax Disclosure [Abstract]
Foreign pre-tax earnings		$ 223.7	$ 235.9	$ 240.1
United States federal statutory rate		35.00%	35.00%	35.00%
Increase (decrease) in valuation allowance		(2.0)	10.4	1.0
Federal net operating loss carryforwards		84.8
Federal capital loss carryforwards		5.3
Foreign net operating loss carryforwards		21.4
Operating loss carryforwards, expiration dates		Between fiscal 2017 and fiscal 2031
Capital loss carryforwards expiration period		5 years
Capital loss carryforwards expiration year		2018
Unremitted earnings of foreign subsidiaries		747.1
Unrecognized tax benefits		54.9	56.8	55.8	106.4
Impact on effective tax rate if unrecognized tax benefits were recognized		53.8	50.3	49.7
Interest and penalties related to uncertain tax positions		2.7	3.9	7.7
Accrued interest and penalties related to uncertain tax positions		35.6	33.7
Net tax benefits related to the settlement of certain tax matters	$ 6.2		$ 6.2	$ 57.2