CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - 9 months ended Dec. 31, 2015 - 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]
Balance (in shares) at Mar. 31, 2015		3,967		1
Balance at Mar. 31, 2015	$ 21,710	$ 40	$ 27,468	$ (7)	$ (5,383)	$ (408)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(1,441)				(1,441)
Other Comprehensive Income (Loss), Net of Tax	(11)					(11)
Stock Issued During Period, Shares, New Issues		3
Stock Issued During Period, Value, New Issues	10		3
Stock Issued During Period, Shares, Treasury Stock Reissued				(1)
Stock Issued During Period, Value, Treasury Stock Reissued				$ 7
Share-based compensation expense	55		55
Capital Contribution By SoftBank	10		10
Balance (in shares) at Dec. 31, 2015		3,970		0
Balance at Dec. 31, 2015	$ 20,333	$ 40	$ 27,536	$ 0	$ (6,824)	$ (419)