Stockholder's Equity (Computation Of Basic And Diluted EPS) (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011
Basic earnings per share:
Net earnings allocated to common shares	$ 106.3	$ 119.9	$ 258.3	$ 330.3
Weighted average number of common shares outstanding	149.7	167.2	155.8	172.0
Basic earnings per share	$ 0.71	$ 0.72	$ 1.66	$ 1.92
Diluted earnings per share:
Net earnings allocated to common shares	$ 106.3	$ 119.9	$ 258.3	$ 330.3
Weighted average number of common shares outstanding	149.7	167.2	155.8	172.0
Incremental shares from assumed conversions of share-based awards	2.9	2.3	3.1	3.2
Adjusted weighted average number of common shares outstanding	152.6	169.5	158.9	175.2
Diluted earnings per share	$ 0.70	$ 0.71	$ 1.63	$ 1.88