Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Sep. 30, 2014	Mar. 31, 2014
Statement of Financial Position [Abstract]
Accumulated depreciation	$ 845	$ 828
Preferred stock, No par value (in dollars per share)	$ 0	$ 0
Preferred stock, Shares authorized	10,000,000	10,000,000
Preferred stock, Shares issued	0	0
Preferred stock, Shares outstanding	0	0
Common stock, Par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, Shares authorized	1,100,000,000	1,100,000,000
Common stock, Shares issued	589,695,081	589,695,081
Common stock, Shares outstanding	440,334,597	438,740,478
Treasury stock, Shares	149,360,484	150,954,603