Share-Based Compensation (Stock Option Activity) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Share-based Compensation [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	6		7
Granted, Shares	1
Exercised, Shares	(2)
Vested and Expected to Vest, Shares	5	[1]
Vested and Exercisable, Shares	3
Outstanding, Weighted-Average Exercise Price, Beginning of Period	$ 65.79
Granted, Weighted-Average Exercise Price	$ 120.79
Exercised, Weighted-Average Exercise Price	$ 56.74
Outstanding, Weighted-Average Exercise Price, End of Period	$ 78.07		$ 65.79
Vested and Expected to Vest, Weighted-Average Exercise Price	$ 77.27	[1]
Vested and Exercisable, Weighted-Average Exercise Price	$ 61.07
Outstanding, Weighted-Average Remaining Contractual Term, Beginning of Period, Years	4 years		4 years
Outstanding, Weighted-Average Remaining Contractual Term, End of Period, Years	4 years		4 years
Vested and Expected to Vest, Weighted-Average Remaining Contractual Term, Years	4 years	[1]
Vested and Exercisable, Weighted-Average Remaining Contractual Term, Years	3 years
Outstanding, Aggregate Intrinsic Value, Beginning of Period	$ 260	[2]
Outstanding, Aggregate Intrinsic Value, End of Period	473	[2]	260	[2]
Vested and Expected to Vest, Aggregate Intrinsic Value	472	[1],[2]
Vested and Exercisable, Aggregate Intrinsic Value	$ 281	[2]

[1] The number of options expected to vest takes into account an estimate of expected forfeitures.

[2] The intrinsic value is calculated as the difference between the period-end market price of the Company’s common stock and the exercise price of “in-the-money” options.