Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2017	Mar. 31, 2017
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 11	$ 11
Accumulated depreciation	$ 860	$ 841
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	412,196,271	413,409,346
Treasury stock, Shares	177,498,810	176,285,735