Consolidated Statement of Shareholder's Equity (USD $) In Millions	Total	Capital stock	Additional paid-in capital	Accumulated other comprehensive (loss) income	Retained earnings
BALANCE AT at Mar. 31, 2009	$ 4,093	$ 915	$ 1	$ (63)	$ 3,240
Net income	1,063	0	0	0	1,063
Net unrealized gain (loss) on available-for-sale marketable securities, net of tax benefit/provision	154	0	0	154	0
Reclassification adjustment for net loss (gain) on available-for-sale marketable securities included in net income, net of tax	13	0	0	13	0
Total comprehensive income	1,230	0	0	167	1,063
Stock-based compensation	0
Dividends	(50)	0	0	0	(50)
BALANCE AT at Mar. 31, 2010	5,273	915	1	104	4,253
Net income	1,853	0	0	0	1,853
Net unrealized gain (loss) on available-for-sale marketable securities, net of tax benefit/provision	4	0	0	4	0
Reclassification adjustment for net loss (gain) on available-for-sale marketable securities included in net income, net of tax	(8)	0	0	(8)	0
Total comprehensive income	1,849	0	0	(4)	1,853
Stock-based compensation	0
Dividends	(266)	0	0	0	(266)
BALANCE AT at Mar. 31, 2011	6,856	915	1	100	5,840
Net income	1,486	0	0	0	1,486
Net unrealized gain (loss) on available-for-sale marketable securities, net of tax benefit/provision	43	0	0	43	0
Reclassification adjustment for net loss (gain) on available-for-sale marketable securities included in net income, net of tax	17	0	0	17	0
Total comprehensive income	1,546	0	0	60	1,486
Stock-based compensation	1	0	1	0	0
Dividends	(741)	0	0	0	(741)
BALANCE AT at Mar. 31, 2012	$ 7,662	$ 915	$ 2	$ 160	$ 6,585