(Schedule Of Stock Option Activity) (Details) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Mar. 31, 2018 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options, Outstanding, Beginning Balance | shares	2,377
Options, Granted | shares	5
Options, Exercised | shares	(764)
Options, forfeited, cancelled or expired | shares	(3)
Options, Outstanding, Ending Balance | shares	1,615
Options, vested and expected to vest | shares	1,615
Options, Exercisable | shares	1,615
Weighted-average exercise price of options outstanding, beginning balance | $ / shares	$ 33.35
Weighted-average exercise price of options granted during period | $ / shares	113.39
Weighted-Average Exercise Prices, Exercised during period | $ / shares	40.30
Weighted-Average Exercise Prices, Forfeited, cancelled or expired during period | $ / shares	41.71
Weighted-average exercise price of options outstanding, ending balance | $ / shares	30.28
Weighted-average exercise price of options vested and expected to vest | $ / shares	30.28
Weighted-average exercise prices of options exercisable | $ / shares	$ 30.28
Weighted-average remaining contractual term of options outstanding	5 years 5 months 10 days
Weighted-average remaining contractual term of options vested and expected to vest	5 years 5 months 10 days
Weighted-average remaining contractual term of options exercisable	5 years 5 months 10 days
Aggregate intrinsic value of options outstanding | $	$ 147
Aggregate intrinsic value of options vested and expected to vest | $	147
Aggregate intrinsic value of options exercisable | $	$ 147