Stockholders' Equity (Details Textual) (USD $) Share data in Millions, unless otherwise specified	12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2010
Stockholders' Equity (Textual) [Abstract]
Weighted average potential anti-dilutive common shares excluded from the calculation of diluted EPS	1.6	1.4	5.2
Amount authorized by Board of Directors to repurchase common stock	$ 5,000,000,000
Shares repurchased, shares	19.2	10.6	7.5
Shares repurchased, amount	780,500,000	439,000,000	275,100,000
Remaining authorized amount in stock repurchase program	850,200,000
Shares repurchased to satisfy employee tax withholding obligations, shares	0.9	0.6	0.4
Shares repurchased to satisfy employee tax withholding obligations, amount	$ 38,200,000	$ 25,100,000	$ 13,000,000