Consolidated Statements of Stockholders' Equity (USD $) In Millions, except Share data in Thousands	Total	Common Class A	Common stock, Class B, nonvoting	Additional Paid-in Capital	Retained Earnings	Treasury Stock, at Cost	Accumulated Other Comprehensive (Loss) Income, Net of Tax
Beginning Balance at Apr. 30, 2009		$ 9	$ 15	$ 67	$ 2,189	$ (331)	$ (133)
Beginning Balance, shares at Apr. 30, 2009		56,590	93,537
Net income	449				449
Cash dividends ($1.18, $2.24, and $1.34 per share in 2010, 2011, and 2012, respectively)					(174)
Net other comprehensive (loss) income	(43)						(43)
Stock issued under compensation plans						13
Stock issued under compensation plans, shares		23	223
Stock-based compensation expense				8
Loss on issuance of treasury stock issued under compensation plans				(19)
Excess tax benefits from stock-based awards				3
Acquisition of treasury stock						(158)
Acquisition of treasury stock, shares		(12)	(3,398)
Total Common Shares Outstanding	146,963	56,601	90,362
Ending Balance at Apr. 30, 2010	1,895	9	15	59	2,464	(476)	(176)
Ending Balance, shares at Apr. 30, 2010	146,963	56,601	90,362
Net income	572				572
Cash dividends ($1.18, $2.24, and $1.34 per share in 2010, 2011, and 2012, respectively)					(326)
Net other comprehensive (loss) income	45						45
Stock issued under compensation plans						14
Stock issued under compensation plans, shares			267
Stock-based compensation expense				9
Loss on issuance of treasury stock issued under compensation plans				(21)
Excess tax benefits from stock-based awards				8
Acquisition of treasury stock						(136)
Acquisition of treasury stock, shares		(40)	(2,200)
Total Common Shares Outstanding	144,990	56,561	88,429
Ending Balance at Apr. 30, 2011	2,060	9	15	55	2,710	(598)	(131)
Ending Balance, shares at Apr. 30, 2011	144,990	56,561	88,429
Net income	513				513
Cash dividends ($1.18, $2.24, and $1.34 per share in 2010, 2011, and 2012, respectively)					(192)
Net other comprehensive (loss) income	(99)						(99)
Stock issued under compensation plans						13
Stock issued under compensation plans, shares			245
Stock-based compensation expense				9
Loss on issuance of treasury stock issued under compensation plans				(23)
Excess tax benefits from stock-based awards				8
Acquisition of treasury stock						(220)
Acquisition of treasury stock, shares		(310)	(2,851)
Total Common Shares Outstanding	142,074	56,251	85,823
Ending Balance at Apr. 30, 2012	$ 2,069			$ 49	$ 3,031	$ (805)	$ (230)
Ending Balance, shares at Apr. 30, 2012	142,074	56,251	85,823