CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - 3 months ended Jun. 30, 2017 - USD ($) shares in Millions, $ in Millions	Total	Common Stock [Member]	Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]
Balance (in shares) at Mar. 31, 2017		3,989
Balance at Mar. 31, 2017	$ 18,808	$ 40	$ 27,756	$ (8,584)	$ (404)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	206			206
Other Comprehensive Income (Loss), Net of Tax	(4)				(4)
Stock Issued During Period, Shares, New Issues		7
Stock Issued During Period, Value, New Issues	9		9
Share-based compensation expense	40		40
Capital contribution by SoftBank	2		2
Other, net	(46)		(46)
Balance (in shares) at Jun. 30, 2017		3,996
Balance at Jun. 30, 2017	$ 19,015	$ 40	$ 27,761	$ (8,378)	$ (408)