Convertible Debt - Additional Information (Detail) (USD $)	0 Months Ended	1 Months Ended	12 Months Ended					12 Months Ended	1 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended		1 Months Ended	12 Months Ended
	Jan. 09, 2012	Nov. 30, 2006	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011 Interest Rate Swap	Dec. 31, 2010 Interest Rate Swap	Dec. 31, 2011 Convertible Senior Notes 2013	Nov. 30, 2006 Purchased Options	Dec. 31, 2011 Purchased Options	Dec. 31, 2011 Purchased Options	Dec. 31, 2011 Purchased Options Group 1	Dec. 31, 2011 Purchased Options Group 2	Nov. 30, 2006 Sold Warrants	Dec. 31, 2011 Sold Warrants
Issuance date		11/1/2006
Proceed from issuance of senior unsecured obligations		$ 3,450,000,000
Debt instrument, convertible, terms of conversion feature			(1) during the five business-day period after any five consecutive trading-day period (the “measurement period”) in which the price per Note for each day of that measurement period was less than 98% of the product of the last reported sale price of our common stock and the conversion rate on each such day; (2) during any calendar quarter, if the last reported sale price of our common stock for 20 or more trading days in a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter exceeds 130% of the applicable conversion price in effect on the last trading day of the immediately preceding calendar quarter; or (3) upon the occurrence of certain events specified in the Notes. Additionally, the 2013 Notes will become convertible during the last three months prior to their maturity.
Shares of our common stock converted per one thousand dollars of principal amount of Notes		62.1978
Conversion premium		27.50%
Conversion price		$ 16.08
Conversion premium based on the closing price		55.00%
Closing price per share		$ 12.61
Convertible debt, carrying amount								1,724,500,000
Convertible debt, fair value								2,500,500,000
Carrying amount of the equity component								263,500,000
Semi annual Interest rate			1.75%
Debt Instrument, frequency of periodic payment			Semi-annually
Debt Instrument, unamortized discount								119,300,000
Debt amortization period			will be fully amortized by December 31, 2013.
Effective interest rate			5.60%	5.60%	5.60%
Common stock at an exercise price														$ 19.55
Proceeds from the sale of the warrants														391,100,000
Aggregate amount paid for purchased options			140,993,000	0	0				669,100,000
Cash payment to noteholders for outstanding principle of converted Notes	1,699,800,000
Shares issued to noteholders for the excess of the conversion value over the principle amount of converted Notes	29,500,000
Value of the conversion value over the principle amount of converted Notes	661,400,000
Converted Notes								500,000
Purchased Options Exercised												107,500,000
Purchased Options Shares Received										29,500,000
Purchased Options Expiration													107,500,000
Description of derivative transaction associated with convertible debt											In connection with the issuance of the Notes, we entered into separate convertible note hedge transactions with respect to our common stock (the “Purchased Options”). The Purchased Options allow us to receive shares of our common stock and/or cash related to the excess conversion value that we would pay to the holders of the Notes upon conversion. The Purchased Options will cover, subject to customary anti-dilution adjustments, approximately 215 million shares of our common stock.				We also entered into separate transactions in which we sold warrants to acquire, subject to customary anti-dilution adjustments, approximately 215 million shares of our common stock at an exercise price of approximately $19.55 per share of our common stock. Half of the associated warrants have expiration dates between February 15, 2012 and March 14, 2012 and the remaining half of the associated warrants have expiration dates between February 18, 2014 and March 18, 2014.
Notional amount of cash flow hedges							900,000,000
Realized loss on replaced interest rate swap contracts						$ 141,000,000