Convertible Debt - Additional Information (Detail) (USD $)	0 Months Ended	1 Months Ended	3 Months Ended
	Jan. 09, 2012	Nov. 30, 2006	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011	Dec. 31, 2010
Issuance date		11/13/2006
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 2013 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 2013 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, fair value			3,191,887,000
Semi annual Interest rate			1.75%
Debt Instrument, frequency of periodic payment			Semi-annually
Debt amortization period			will be fully amortized by December 31, 2013.
Effective interest rate			5.60%		5.60%
Cash payment to noteholders for outstanding principle of converted Notes	1,699,816,000		1,699,816,000		0
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
Aggregate notional amount of interest rate swap contracts designated as cash flow hedges						900,000,000
Realized loss on replaced interest rate swap contracts				141,000,000
Convertible Notes 1 Point 75 Percent Due 2013
Convertible debt, carrying amount			1,710,300,000
Convertible debt, fair value			3,191,887,000
Carrying amount of the equity component			279,200,000
Debt Instrument, unamortized discount			103,600,000
Amount of converted Notes			14,700,000
Purchased Options
Aggregate amount paid for purchased options		669,100,000
Purchased Options Shares Received				29,500,000
Description of derivative transaction associated with convertible debt			In connection with the issuance of the 2011 Notes and 2013 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 2011 Notes and 2013 Notes upon conversion. The Purchased Options will cover, subject to customary anti-dilution adjustments, approximately 215 million shares of our common stock.
Sold Warrants
Common stock at an exercise price		$ 19.55
Proceeds from the sale of the warrants		$ 391,100,000
Description of derivative transaction associated with convertible debt			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. We received aggregate proceeds of $391.1 million from the sale of the associated warrants. Upon exercise, the value of the warrants is required to be settled in shares. Half of the associated warrants were exercised 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.
Exercised Warrants
Shares issues for exercised warrants			32,300,000
Group 1 | Purchased Options
Purchased Options Exercised				107,500,000
Group 2 | Purchased Options
Purchased Options Exercised				107,500,000