Common Equity Units (Details) (USD $)	12 Months Ended			1 Months Ended		1 Months Ended		1 Months Ended		1 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Oct. 31, 2012 Common Stock [Member]	Oct. 10, 2012 Common Stock [Member]	Oct. 31, 2012 Senior Notes [Member] Debt Remarketing Series C Tranche 1 [Member]	Oct. 04, 2012 Senior Notes [Member] Debt Remarketing Series C Tranche 1 [Member]	Oct. 31, 2012 Senior Notes [Member] Debt Remarketing Series C Tranche 2 [Member]	Oct. 04, 2012 Senior Notes [Member] Debt Remarketing Series C Tranche 2 [Member]	Oct. 31, 2012 Senior Notes [Member] Debt Remarketing Series C [Member]	Dec. 31, 2010 Estimated Fair Value [Member]	Dec. 31, 2010 Series C Purchase Contract [Member]	Dec. 31, 2010 Series D Purchase Contract [Member]	Dec. 31, 2010 Series E Purchase Contract [Member]	Dec. 31, 2010 Alico Transaction [Member]
Common Equity Units [Abstract]
Effective date of acquisition			Nov. 01, 2010
Equity Units, Shares Transferred			40,000,000
Equity Units Stated Interest Percentage			5.00%
Equity Units, Aggregate Purchase Price per Unit			$ 75
Common Stock, Par, Common Equity Units	$ 0.01	$ 0.01	$ 0.01
Equity Units, Purchase Price Per Contract Settlement			$ 25
Equity Units, Beneficial Interest Stated Percentage			2.50%
Weighted Average Share Price, Trading Day Periods			20 days
Equity Units, Stock Reference Price			$ 35.42
Equity Units, Stock Threshold Appreciation Price			$ 44.275
Proceeds from Purchase Contracts Settlement	2,000,000,000
Stock Purchase Contracts, Minimum Shares of Common Stock issued from Settlement	45,200,000
Stock Purchase Contracts, Maximum Shares of Common Stock issued from Settlement	56,500,000
Stock Purchase Contracts, Value at Issuance			247,000,000
Stock Purchase Contracts, Payments Made	84,000,000	102,000,000
Debt Instrument, Interest Rate, Average Stated			1.98%
Stock Purchase Contracts, Average Stated Interest Rate			3.02%
Issuance of stock purchase contracts related to common equity units			(69,000,000)
Class of Stock [Line Items]
Value of securities issued for business acquisition			3,000,000,000								3,200,000,000
Debt Security, Principle Amount															1,000,000,000
Purchase Contract Settlement Date												Oct. 10, 2012	Sep. 11, 2013	Oct. 08, 2014
Debt Instrument, Interest Rate, Stated Percentage							1.756%		3.048%
Debt Instrument, Maturity Date						Dec. 15, 2017		Dec. 15, 2022
Proceeds from remarketing										0
Proceeds from issuance of common stock				$ 1,000,000,000
Common stock, shares issued	1,094,880,623	1,061,150,915			28,231,956