Consolidated Statement of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 244	$ 326	$ 335	$ 803
Other comprehensive income, net of tax:
Net unrealized gains (losses) on available-for-sale marketable securities, net of tax	16	42	(38)	53
Reclassification adjustment for net losses (gains) on available-for-sale marketable securities included in net income, net of tax	9	(3)	25	(5)
Other comprehensive income (loss)	25	39	(13)	48
Comprehensive income	$ 269	$ 365	$ 322	$ 851

The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to the economic entity, including both controlling (parent) and noncontrolling interests. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, including any and all transactions which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

+ References+ Details

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

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-Glossary Other Comprehensive Income

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-Name Accounting Research Bulletin (ARB)

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+ Details

- Definition

Net of tax amount of unrealized holding gain (loss) before reclassification adjustments and transfers on available-for-sale securities.

+ References

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+ Details