Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock
Beginning balance at Mar. 31, 2015	$ 5,625	$ 59	$ 3,631	$ 6,221	$ (418)	$ (3,868)
Net income	783			783
Other comprehensive income (loss)	2				2
Comprehensive income	785
Share-based compensation	97		97
Dividends declared	(429)			(429)
Release of restricted stock, exercise of common stock options, ESPP and other items	7		(64)			71
Treasury stock purchased	(707)					(707)
Ending balance at Mar. 31, 2016	5,378	59	3,664	6,575	(416)	(4,504)
Net income	775			775
Other comprehensive income (loss)	(67)				(67)
Comprehensive income	708
Share-based compensation	108		108
Dividends declared	(428)			(428)
Release of restricted stock, exercise of common stock options, ESPP and other items	23		(70)	1		92
Treasury stock purchased	(100)					(100)
Ending balance at Mar. 31, 2017	5,689	59	3,702	6,923	(483)	(4,512)
Net income	476			476
Other comprehensive income (loss)	193				193
Comprehensive income	669
Share-based compensation	120		120
Dividends declared	(428)			(428)
Release of restricted stock, exercise of common stock options, ESPP and other items	8		(78)			86
Treasury stock purchased	(163)					(163)
Ending balance at Mar. 31, 2018	$ 5,895	$ 59	$ 3,744	$ 6,971	$ (290)	$ (4,589)