Share-Based Compensation - Summary of Options Outstanding (Details) shares in Millions	12 Months Ended
	Mar. 31, 2017 $ / shares shares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Options Outstanding at Year End (in shares) | shares	4
Number of Options Exercisable at Year End (in shares) | shares	2
Range One
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices lower limit (in dollars per share)	$ 67.81
Range of exercise prices upper limit (in dollars per share)	$ 153.87
Number of Options Outstanding at Year End (in shares) | shares	2
Weighted- Average Remaining Contractual Life (Years)	2 years
Weighted- Average Exercise Price (in dollars per share)	$ 95.74
Number of Options Exercisable at Year End (in shares) | shares	2
Weighted- Average Exercise Price (in dollars per share)	$ 93.13
Range Two
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices lower limit (in dollars per share)	153.88
Range of exercise prices upper limit (in dollars per share)	$ 239.93
Number of Options Outstanding at Year End (in shares) | shares	2
Weighted- Average Remaining Contractual Life (Years)	5 years
Weighted- Average Exercise Price (in dollars per share)	$ 196.35
Number of Options Exercisable at Year End (in shares) | shares	0
Weighted- Average Exercise Price (in dollars per share)	$ 196.78