CONSOLIDATED STATEMENT OF SHAREHOLDER'S EQUITY (USD $) In Millions	Total	Capital stock	Additional paid-in capital	Accumulated other comprehensive income (loss)	Retained earnings [Member]
Balance at Mar. 31, 2010	$ 5,273	$ 915	$ 1	$ 104	$ 4,253
Net income	1,465	0	0	0	1,465
Net unrealized (loss) gain on available-for-sale marketable securities, net of tax	(16)	0	0	(16)	0
Reclassification adjustment for net loss (gain) on available-for-sale marketable securities, included in net income, net of tax	(2)	0	0	(2)	0
Total comprehensive income	1,447	0	0	(18)	1,465
Stock-based compensation	0
Dividends	(266)	0	0	0	(266)
Balance at Dec. 31, 2010	6,454	915	1	86	5,452
Balance at Mar. 31, 2011	6,856	915	1	100	5,840
Net income	1,348	0	0	0	1,348
Net unrealized (loss) gain on available-for-sale marketable securities, net of tax	(8)	0	0	(8)	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	1,357	0	0	9	1,348
Stock-based compensation	1	0	1	0	0
Dividends	(741)	0	0	0	(741)
Balance at Dec. 31, 2011	$ 7,473	$ 915	$ 2	$ 109	$ 6,447