CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Millions	Total	Common Stock [Member]	Paid-in Capital [Member]	Treasury Shares [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Noncontrolling Interest [Member]
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	$ (1,206)
Balance (in shares) at Mar. 31, 2016		3,974,000,000		1,000,000
Balance at Mar. 31, 2016	19,783	$ 40	$ 27,563	$ (3)	$ (7,378)	$ (439)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(1,206)
Other comprehensive (loss) income	35					35
Issuance of common stock, net (in shares)		15,000,000
Issuance of common stock, net	50		47
Issuance (repurchase) of common stock, net (in shares)				(1,000,000)
Issuance (repurchase) of common stock, net				$ 3
Share-based compensation expense	91		91
Capital contribution by SoftBank			6
Other, net			49
Balance (in shares) at Mar. 31, 2017		3,989,000,000		0
Balance at Mar. 31, 2017	18,808	$ 40	27,756	$ 0	(8,584)	(404)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest							$ (12)
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	7,377
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	7,389				7,389
Other comprehensive (loss) income	31					31
Issuance of common stock, net (in shares)		16,000,000
Issuance of common stock, net	21		21
Share-based compensation expense	182		182
Capital contribution by SoftBank			6
Other, net			(54)
Balance (in shares) at Mar. 31, 2018		4,005,000,000		0
Balance at Mar. 31, 2018	26,356	$ 40	27,884	$ 0	(1,255)	(313)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Tax Act reclassification					(60)	60
Noncontrolling Interest, Period Increase (Decrease)	48		$ (27)				75
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ 26,419						63
Common stock, shares, issued	4,005,000,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest							0
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	$ (1,943)
Net (loss) income	(1,943)				(1,943)
Other comprehensive (loss) income	(71)					(71)
Other Comprehensive Income (Loss), Net of Tax less cumulative effect of accounting changes	(71)
Issuance of common stock, net (in shares)		76,000,000	1,000,000
Issuance of common stock, net	291		$ 290
Share-based compensation expense	132		132
Capital contribution by SoftBank			6
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income	1,315
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Operating Results	(8)
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	1,307
Other, net			(14)
Balance (in shares) at Mar. 31, 2019		4,081,000,000		0
Balance at Mar. 31, 2019	26,072	$ 41	28,306	$ 0	$ (1,883)	$ (392)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Noncontrolling Interest, Period Increase (Decrease)	0		$ 8				(8)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ 26,127						$ 55
Common stock, shares, issued	4,081,000,000