CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) shares in Millions, $ in Millions	Total	Common Stock [Member]	Paid-in Capital [Member]	Treasury Stock [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]	Noncontrolling Interest [Member]
Total stockholders' equity	$ 26,356			$ 0
Net Income (Loss) Attributable to Parent	176
Balance (in shares) at Mar. 31, 2018		4,005
Beginning Balance at Mar. 31, 2018	26,419	$ 40	$ 27,884		$ (1,255)	$ (313)	$ 63
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	173						(3)
Other Comprehensive Income, Other, Net of Tax						4
Stock Issued During Period, Shares, New Issues		8
Stock Issued During Period, Value, New Issues	(2)		2
Stock Issued During Period, Shares, Treasury Stock Reissued				1
Stock Issued During Period, Value, Treasury Stock Reissued				$ (4)
Share-based compensation expense	40		40
Capital contribution by SoftBank	1		1
Cumulative effect of accounting changes	1,307				1,315	(8)
Other, net	3		3
Increase (decrease) attributable to noncontrolling interests	0		8				(8)
Balance (in shares) at Jun. 30, 2018		4,013		1
Ending Balance at Jun. 30, 2018	27,945	$ 40	$ 27,938		$ 236	$ (317)	$ 52
Total stockholders' equity	$ 27,893			$ (4)