Stock-Based Compensation (Schedule Of Stock Option Activity) (Details) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended
	Jun. 30, 2018 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Options, Outstanding, Beginning Balance | shares	1,615
Options, Granted | shares	1
Options, Exercised | shares	(24)
Options, Outstanding, Ending Balance | shares	1,592
Options, Vested and expected to vest | shares	1,592
Options, Exercisable | shares	1,592
Weighted-average exercise price of options outstanding, beginning balance | $ / shares	$ 30.28
Weighted-average exercise price of options granted during period | $ / shares	119.83
Weighted-average exercise price of options exercised during the period | $ / shares	30.17
Weighted-average exercise price of options outstanding, ending balance | $ / shares	30.34
Weighted-average exercise price of options vested and expected to vest | $ / shares	30.34
Weighted-average exercise price of options exercisable | $ / shares	$ 30.34
Weighted-average remaining contractual term of options outstanding	5 years 2 months 23 days
Weighted-average remaining contractual term of options vested and expected to vest	5 years 2 months 23 days
Weighted-average remaining contractual term of options exercisable	5 years 2 months 23 days
Aggregate intrinsic value of options outstanding | $	$ 176
Aggregate intrinsic value of options vested and expected to vest | $	176
Aggregate intrinsic value of options exercisable | $	$ 176