Per Share Data (Narrative) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended
	Jul. 10, 2018	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Class of Warrant or Right, Unissued			24
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			20
Options and RSUs [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Number of shares that had no effect on computation of dilutive weighted average number of shares outstanding			59
Options and Restricted Stock Units [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Number of shares that had no effect on computation of dilutive weighted average number of shares outstanding		47
Warrant [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Number of shares that had no effect on computation of dilutive weighted average number of shares outstanding		4
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 5.25
Warrant [Member] | Subsequent Event [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	55
Proceeds from Warrant Exercises	$ 287
Warrant [Member] | SoftBank [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Number of shares that had no effect on computation of dilutive weighted average number of shares outstanding		2
Employee Stock Option [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		9	4