Debt and Equity Transactions (Unaudited) (Details) (USD $)	3 Months Ended				1 Months Ended	3 Months Ended		3 Months Ended		3 Months Ended		3 Months Ended		3 Months Ended					1 Months Ended	3 Months Ended			3 Months Ended		3 Months Ended		3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 Bank Term Loan [Member]	Feb. 14, 2013 Bank Term Loan [Member]	Feb. 28, 2012 Senior Notes [Member]	Mar. 31, 2013 Senior Notes [Member]	Mar. 07, 2013 Senior Notes [Member]	Mar. 31, 2013 Senior Notes [Member] 2.375% Senior Notes due March 2018 [Member]	Mar. 07, 2013 Senior Notes [Member] 2.375% Senior Notes due March 2018 [Member]	Mar. 31, 2013 Senior Notes [Member] 3.100% Senior Notes due March 2020 [Member]	Mar. 07, 2013 Senior Notes [Member] 3.100% Senior Notes due March 2020 [Member]	Mar. 31, 2013 Senior Notes [Member] 3.875% Senior Notes due March 2023 [Member]	Mar. 07, 2013 Senior Notes [Member] 3.875% Senior Notes due March 2023 [Member]	Mar. 31, 2013 Senior Notes [Member] 5.450% Senior Notes due March 2043 [Member]	Mar. 07, 2013 Senior Notes [Member] 5.450% Senior Notes due March 2043 [Member]	Feb. 28, 2012 Senior Notes [Member] 1.40% Senior Notes due 2015 [Member]	Feb. 28, 2012 Senior Notes [Member] 2.15% Senior Notes due 2017 [Member]	Feb. 28, 2012 Senior Notes [Member] Senior Notes Due 2022 3 Point 55 Percent [Member]	Mar. 31, 2012 Senior Notes [Member] 8.375% Senior Notes due 2017 [Member]	Mar. 31, 2012 Senior Notes [Member] 8.375% Senior Notes due 2017 [Member]	Mar. 31, 2013 Revolving Credit Facility [Member]	Feb. 14, 2013 Revolving Credit Facility [Member]	Mar. 31, 2013 Bridge Loan [Member]	Feb. 14, 2013 Bridge Loan [Member]	Mar. 31, 2013 Option 1 [Member] Bank Term Loan [Member]	Feb. 14, 2013 Option 1 [Member] Bank Term Loan [Member]	Mar. 31, 2013 Option 2 [Member] Bank Term Loan [Member]	Feb. 14, 2013 Option 2 [Member] Bank Term Loan [Member]
Extinguishment of Debt [Line Items]
Debt Instrument, Agreement Date	Mar. 07, 2013		Feb. 14, 2013																		Feb. 14, 2013
Debt Instrument, Maturity Date																					Mar. 30, 2016
Face amount of senior notes sold				$ 4,000,000,000			$ 6,500,000,000		$ 1,500,000,000		$ 1,000,000,000		$ 2,000,000,000		$ 2,000,000,000	$ 500,000,000	$ 500,000,000	$ 2,000,000,000						$ 9,500,000,000
Long-term Debt, Maturities, Repayments of Principal in Year Two, Percent				10.00%
Long-term Debt, Maturities, Repayments of Principal in Year Three, Percent				15.00%
Long-term Debt, Maturities, Repayments of Principal in Year Four, Percent				20.00%
Debt Instrument, Maturity Date, Description			five years from the date of the first borrowing
Debt Instrument, Description of Variable Rate Basis																					LIBOR				LIBOR		alternate-based rate
Debt Instrument, Basis Spread on Variable Rate																						1.50%				1.50%		0.50%
Term of Debt Agreement			5 years					5 years		7 years		10 years		30 years							5 years
Line of Credit Facility, Maximum Borrowing Capacity																						3,000,000,000
Amount of revolving credit facility available to subsidiary																						500,000,000
Debt Instrument, Interest Rate (percent)									2.375%		3.10%		3.875%		5.45%	1.40%	2.15%	3.55%	8.375%	8.375%
Proceeds from Issuance of Long-term Debt					2,970,000,000	6,400,000,000
Debt Instrument, Frequency of Periodic Payment						March 15 and September 15
Debt Instrument, Date of First Required Payment						Sep. 15, 2013
Redemption price percentage to principal amount										101.00%		101.00%		101.00%					104.553%
Losses on early extinguishment of debt	45,000,000	168,000,000																		168,000,000			45,000,000
Losses on early extinguishment of debt, net of tax																				149,000,000			40,000,000
Debt Instrument, Redemption Date																			Mar. 14, 2012
Extinguishment of Debt, Amount																			$ 3,000,000,000