Stockholders' Equity - Schedule of Share Repurchases (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014	Oct. 31, 2015	May. 31, 2015
Stockholders' Equity Note [Abstract]
Total Number of Shares Purchased	8.7	1.5	0.0
Average price paid per share (in dollars per share)	$ 173.64	$ 226.55	$ 0.00
Approximate Dollar Value of Shares that May Yet Be Purchased Under the Programs
Beginning balance	$ 0	$ 340	$ 340
Shares repurchased	(1,504)	(340)	0
Shares repurchase plans authorized				$ 2,000	$ 500
Ending balance	$ 996	$ 0	$ 340