Share-Based Compensation - Schedule of Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Shares
Beginning balance (in shares)	5
Granted (in shares)	1
Cancelled (in shares)	(1)
Exercised (in shares)	(1)
Ending balance (in shares)	4	5
Weighted- Average Exercise Price
Beginning balance (in dollars per share)	$ 95.01
Granted (in dollars per share)	236.77
Cancelled (in dollars per share)	149.19
Exercised (in dollars per share)	63.75
Ending balance (in dollars per share)	$ 118.95	$ 95.01
Weighted- Average Remaining Contractual Term (Years)
Stock options outstanding, remaining contractual term	3 years	4 years
Stock options outstanding, aggregate intrinsic value	$ 201	$ 539
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest [Abstract]
Stock options vested and expected to vest (in shares)	3
Stock options vested and exercisable (in shares)	2
Stock options vested and expected to vest, weighted average exercise price (in dollars per share)	$ 118.21
Stock options vested and exercisable, weighted average exercise price (in dollars per share)	$ 85.15
Stock options vested and expected to vest, weighted average remaining contractual term	3 years
Stock options vested and exercisable, weighted average remaining contractual term	2 years
Stock options vested and expected to vest, aggregate intrinsic value	$ 200
Stock options vested and exercisable, aggregate intrinsic value	$ 173