Debt - Additional Information (Detail) (USD $) Share data in Millions, except Per Share data, unless otherwise specified		0 Months Ended	3 Months Ended		1 Months Ended	3 Months Ended	6 Months Ended	0 Months Ended	1 Months Ended		1 Months Ended		3 Months Ended		6 Months Ended
	Mar. 17, 2014 Warrant	Jan. 07, 2014 Convertible Senior Notes 2013	Jun. 30, 2014 Convertible Senior Notes 2013	Nov. 13, 2006 Convertible Senior Notes 2013	Nov. 30, 2006 Convertible Senior Notes 2011 and 2013	Jun. 30, 2013 Convertible Senior Notes 2011 and 2013	Jun. 30, 2013 Convertible Senior Notes 2011 and 2013	Jan. 07, 2014 Purchased Options	Nov. 30, 2006 Purchased Options	Dec. 31, 2013 Purchased Options	Nov. 30, 2006 Sold Warrants	Nov. 13, 2006 Sold Warrants	Jun. 30, 2014 Exercised Warrants	Jun. 30, 2014 Long-term Debt	Jun. 30, 2014 Long-term Debt	Jun. 30, 2013 Long-term Debt	Jun. 30, 2014 Interest Rate Swap	Dec. 31, 2010 Interest Rate Swap
Senior Notes			$ 1,725,000,000	$ 1,725,000,000
Proceeds from issuance of senior unsecured obligations					3,500,000,000
Cash payment to noteholders for outstanding principal of converted Notes		1,700,000,000
Shares issued to noteholders for the excess of the conversion value over the principal amount of converted Notes		35
Value of the conversion value over the principal amount of converted Notes		858,000,000
Observation period			20 days
Conversion rate for the 2013 Notes in shares of our common stock per one thousand dollars of principal amount of 2013 Notes			62.6978
Conversion premium			26.50%
Conversion price			$ 15.95
Long term debt, aggregate principal																5,500,000,000
Debt Instrument, unamortized discount														6,000,000	6,000,000
Debt Instrument, Interest Rate During Period						5.60%	5.60%							2.54%	2.54%
Semi-annual interest rate			1.75%	1.75%
Debt Instrument, frequency of periodic payment			semi-annually
Incremental common shares attributable to call options and warrants									215		215
Aggregate amount paid for purchased options									669,000,000
Purchased options shares received								35
Purchased Options Remaining										108
Common stock at an exercise price											$ 19.55	$ 19.31
Proceeds from issuance of warrants											391,000,000
Warrants and Rights Outstanding	109,000,000
Shares issues for exercised warrants													29
Conversion premium based on the closing price											53.00%
Closing price per share												$ 12.61
Aggregate notional amount of interest rate swap contracts designated as cash flow hedges																		900,000,000
Accumulated Other Comprehensive Income (Loss) related to realized losses on settled swaps																	$ 176,000,000