Derivatives and Foreign Exchange Risk Management, Fair Value Hedges (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended				12 Months Ended			1 Months Ended	12 Months Ended				1 Months Ended	12 Months Ended
	Apr. 27, 2012	Apr. 29, 2011	Apr. 27, 2012 March 2012 Agreement	Apr. 27, 2012 March 2011 Agreements	Apr. 27, 2012 March 2011 Agreement 1	Apr. 27, 2012 March 2011 Agreement 2	Apr. 27, 2012 March 2010 Agreements 1 & 2	Aug. 31, 2011 March 2010 Agreement 1	Apr. 27, 2012 March 2010 Agreement 1	Apr. 27, 2012 March 2010 Agreement 2	Apr. 27, 2012 March 2010 Agreement 3	Apr. 29, 2011 March 2010 Agreement 3	Jul. 31, 2011 March 2010 Agreement 3 and 2009 Agreements	Apr. 27, 2012 March 2010 Agreement 3 and 2009 Agreements	Apr. 27, 2012 December 2009 Agreement 1	Apr. 27, 2012 December 2009 Agreement 2	Apr. 27, 2012 December 2009 Agreement 3	Apr. 27, 2012 June 2009 Agreement 1	Apr. 27, 2012 June 2009 Agreement 2	Apr. 27, 2012 Interest Rate Swap	Apr. 29, 2011 Interest Rate Swap
Fair Value Hedges
Inception date			Mar. 01, 2012		Mar. 01, 2011	Mar. 01, 2011			Mar. 01, 2010	Mar. 01, 2010	Mar. 01, 2010				Dec. 01, 2009	Dec. 01, 2009	Dec. 01, 2009	Jun. 01, 2009	Jun. 01, 2009
Interest rate derivatives hedged items			2012 Senior Notes due 2022		2011 Senior Notes due 2016	2011 Senior Notes due 2021			$1.250 billion 3.000 percent 2010 Senior Notes due 2015	$600 million 4.750 percent 2010 Senior Notes due 2015	$2.200 billion 1.625 percent 2013 Senior Convertible Notes				$550 million 4.500 percent 2009 Senior Notes due 2014	$550 million 4.500 percent 2009 Senior Notes due 2014	$550 million 4.500 percent 2009 Senior Notes due 2014	$550 million 4.500 percent 2009 Senior Notes due 2014	$550 million 4.500 percent 2009 Senior Notes due 2014
Debt variable rate basis			one-month LIBOR		LIBOR	LIBOR			three-month LIBOR	LIBOR	three-month LIBOR				three-month LIBOR	three-month LIBOR	three-month LIBOR	one-month LIBOR	one-month LIBOR
Basis spread on debt variable rate			0.92%		0.37%	0.66%			0.36%	1.85%	(0.197%)				1.8125%	1.965%	1.981%	1.34%	1.3725%
Fixed interest rate received			3.125%		2.625%	4.125%			3.00%	4.75%	1.625%				4.50%	4.50%	4.50%	4.50%	4.50%
Termination date									Aug. 01, 2011					Jul. 01, 2011
Notional amount of interest rate fair value hedges terminated			$ 675	$ 750			$ 1,850	$ 650			$ 2,200	$ 1,850	$ 900		$ 75	$ 75	$ 100	$ 150	$ 150
Cash receipts upon termination of hedge								42				51	46
Derivative interest accrued on hedge								7				11	10
Unrealized gain on interest rate fair value hedging instruments																				167	109
Unrealized loss on interest rate fair value hedged items																				(167)	(110)
Interest rate fair value hedge ineffectiveness	$ 1	$ 4