Long-Term Debt (Details) (USD $)	1 Months Ended	12 Months Ended		1 Months Ended
	Jan. 31, 2013	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 2013 7.5 % debentures due 2043 [Member]	Jun. 30, 2013 7.327% amortizing notes due 2014 [Member]	Dec. 31, 2013 Notes Payable [Member] 3.191% notes due 2023 [Member]	Dec. 31, 2013 Notes Payable [Member] 1.104% notes due 2017 [Member]	Dec. 31, 2012 Notes Payable [Member] 1.104% notes due 2017 [Member]	Dec. 31, 2013 Notes Payable [Member] 1.718% notes due 2018 [Member]	Dec. 31, 2013 Notes Payable [Member] 2.355% notes due 2022 [Member]	Dec. 31, 2012 Notes Payable [Member] 2.355% notes due 2022 [Member]	Dec. 31, 2013 Notes Payable [Member] 4.95% notes due 2019 [Member]	Dec. 31, 2012 Notes Payable [Member] 4.95% notes due 2019 [Member]	Dec. 31, 2013 Notes Payable [Member] 2.427% notes due 2020 [Member]	Dec. 31, 2013 Notes Payable [Member] 0.889% notes due 2016 [Member]	Dec. 31, 2013 Notes Payable [Member] 7.327% amortizing notes due 2014 [Member]		Dec. 31, 2012 Notes Payable [Member] 7.327% amortizing notes due 2014 [Member]		Dec. 31, 2013 Notes Payable [Member] 7.327% amortizing notes due 2013 [Member]		Dec. 31, 2012 Notes Payable [Member] 7.327% amortizing notes due 2013 [Member]		Dec. 31, 2013 Debentures [Member] 8.625% debentures due 2032 [Member]	Dec. 31, 2012 Debentures [Member] 8.625% debentures due 2032 [Member]	Dec. 31, 2013 Debentures [Member] 8.625 % debentures due 2031 [Member]	Dec. 31, 2012 Debentures [Member] 8.625 % debentures due 2031 [Member]	Dec. 31, 2013 Debentures [Member] 8 % debentures due 2032 [Member]	Dec. 31, 2012 Debentures [Member] 8 % debentures due 2032 [Member]	Dec. 31, 2013 Debentures [Member] 9.75 % debentures due 2020 [Member]	Dec. 31, 2012 Debentures [Member] 9.75 % debentures due 2020 [Member]	Dec. 31, 2013 Debentures [Member] 8.875 % debentures due 2021 [Member]	Dec. 31, 2012 Debentures [Member] 8.875 % debentures due 2021 [Member]	Dec. 31, 2013 Debentures [Member] 7.5 % debentures due 2043 [Member]	Dec. 31, 2012 Debentures [Member] 7.5 % debentures due 2043 [Member]	Dec. 31, 2013 Medium-term Notes [Member] Medium-term notes, maturing from 2021 to 2038 (5.92%) [Member]		Dec. 31, 2012 Medium-term Notes [Member] Medium-term notes, maturing from 2021 to 2038 (5.92%) [Member]		Dec. 31, 2013 Corporate Bond Securities [Member]
Debt Instrument [Line Items]
Long-term debt instruments		$ 11,960,000,000	$ 6,086,000,000			$ 2,250,000,000	$ 2,000,000,000	$ 2,000,000,000	$ 2,000,000,000	$ 2,000,000,000	$ 2,000,000,000	$ 1,500,000,000	$ 1,500,000,000	$ 1,000,000,000	$ 750,000,000	$ 0	[1]	$ 23,000,000	[1]	$ 0	[1]	$ 20,000,000	[1]	$ 147,000,000	$ 147,000,000	$ 107,000,000	$ 107,000,000	$ 74,000,000	$ 74,000,000	$ 54,000,000	$ 54,000,000	$ 40,000,000	$ 40,000,000	$ 0	$ 83,000,000	$ 38,000,000	[2]	$ 38,000,000	[2]
Debt due within one year		0	(20,000,000)
Reclassified from short-term debt		8,000,000,000	5,900,000,000
Total long-term debt		19,960,000,000	11,966,000,000
Interest rate						3.191%	1.104%		1.718%	2.355%		4.95%		2.427%	0.889%	7.327%				7.327%				8.625%		8.625%		8.00%		9.75%		8.875%		7.50%		5.92%
Long-term debt maturing 2014		0
Long-term debt maturing 2015		0
Long-term debt maturing 2016		750,000,000
Long-term debt maturing 2017		2,000,000,000
Long-term debt maturing 2018		2,000,000,000
Long-term debt maturing after 2018		7,210,000,000
Debt issued																																								6,000,000,000
Repayments of debt	$ 20,000,000			$ 83,000,000	$ 23,000,000

[1] Guarantee of ESOP debt.

[2] Weighted-average interest rate at December 31, 2013.