Debt (Details)	3 Months Ended																																												12 Months Ended
	Mar. 31, 2014 USD ($)	Mar. 31, 2013 USD ($)	Dec. 31, 2013 USD ($)	Mar. 31, 2014 Senior Note 4.625% Due in 2013 [Member]	Mar. 31, 2014 Senior Note 4.75% Due in 2014 [Member]	Dec. 31, 2013 Senior Note 4.75% Due in 2014 [Member] USD ($)	Mar. 31, 2014 5.125% senior notes due 2022 [Member] USD ($)	Dec. 31, 2013 5.125% senior notes due 2022 [Member] USD ($)	Mar. 31, 2014 6.625% senior notes due 2042 [Member] USD ($)	Dec. 31, 2013 6.625% senior notes due 2042 [Member] USD ($)	Mar. 31, 2014 Senior Note 4.3% Due in 2042 [Member] USD ($)	Dec. 31, 2013 Senior Note 4.3% Due in 2042 [Member] USD ($)	Mar. 31, 2014 10.0% Notes, due 2068 [Member]	Mar. 31, 2014 6.1% senior notes due 2041 [Member] USD ($)	Dec. 31, 2013 6.1% senior notes due 2041 [Member] USD ($)	Mar. 31, 2014 Senior Note 4.0% Due in 2015 [Member] USD ($)	Dec. 31, 2013 Senior Note 4.0% Due in 2015 [Member] USD ($)	Mar. 31, 2014 Senior Note 7.3% Due in 2015 [Member] USD ($)	Dec. 31, 2013 Senior Note 7.3% Due in 2015 [Member] USD ($)	Mar. 31, 2014 Senior Note 7.5% Due in 2016 [Member] USD ($)	Dec. 31, 2013 Senior Note 7.5% Due in 2016 [Member] USD ($)	Mar. 31, 2014 Senior Note 5.375% Due in 2017 [Member] USD ($)	Dec. 31, 2013 Senior Note 5.375% Due in 2017 [Member] USD ($)	Mar. 31, 2014 Senior Note 4.0% Due in 2017 [Member] USD ($)	Dec. 31, 2013 Senior Note 4.0% Due in 2017 [Member] USD ($)	Mar. 31, 2014 Senior Note 6.3% Due in Two Thousand Eighteen [Member] USD ($)	Dec. 31, 2013 Senior Note 6.3% Due in Two Thousand Eighteen [Member] USD ($)	Mar. 31, 2014 Senior Note 6.0% Due in 2019 [Member] USD ($)	Dec. 31, 2013 Senior Note 6.0% Due in 2019 [Member] USD ($)	Mar. 31, 2014 Senior Note 5.5% Due in 2020 [Member] USD ($)	Dec. 31, 2013 Senior Note 5.5% Due in 2020 [Member] USD ($)	Mar. 31, 2014 Senior Note 7.65% Due in 2027 [Member] USD ($)	Dec. 31, 2013 Senior Note 7.65% Due in 2027 [Member] USD ($)	Mar. 31, 2014 Senior Note 7.375% Due in 2031 [Member] USD ($)	Dec. 31, 2013 Senior Note 7.375% Due in 2031 [Member] USD ($)	Mar. 31, 2014 Senior Note 5.95% Due in 2036 [Member] USD ($)	Dec. 31, 2013 Senior Note 5.95% Due in 2036 [Member] USD ($)	Mar. 31, 2014 Senior Note 6.625% Due in 2042 [Member] USD ($)	Dec. 31, 2013 Senior Note 6.625% Due in 2042 [Member] USD ($)	Mar. 31, 2014 Junior Subordinated Notes 7.75% Due 2042 [Member]	Mar. 31, 2014 Junior Subordinate Notes 8.125% Note Due 2068 [Member]	Mar. 31, 2014 Revolving Credit Facility [Member] USD ($)	Mar. 31, 2014 Senior Note 4.75% Due in 2014 [Member] USD ($)	Dec. 31, 2013 JAPAN Revolving Credit Facility [Member] JPY (¥)	Dec. 31, 2013 Japan, Yen JAPAN	Dec. 31, 2013 United States of America, Dollars USD ($)	Dec. 31, 2013 20b credit facility [Member]	Dec. 31, 2013 5b credit facility [Member]
Debt Instrument [Line Items]
Senior Notes						$ 200,000,000	$ 797,000,000	$ 796,000,000	$ 178,000,000	$ 178,000,000	$ 298,000,000	$ 298,000,000		$ 326,000,000	$ 326,000,000	$ 289,000,000	$ 289,000,000	$ 167,000,000	$ 167,000,000	$ 275,000,000	$ 275,000,000	$ 415,000,000	$ 415,000,000	$ 295,000,000	$ 295,000,000	$ 320,000,000	$ 320,000,000	$ 413,000,000	$ 413,000,000	$ 499,000,000	$ 499,000,000	$ 79,000,000	$ 79,000,000	$ 63,000,000	$ 63,000,000	$ 298,000,000	$ 298,000,000	$ 295,000,000	$ 295,000,000				$ 0
Maximum amount available under the line of credit facility																																										1,750,000,000		5,000,000,000		0
Line of credit facility maximum borrowing capacity available to support letters of credit																																										250,000,000
Ratio of Indebtedness to Net Capital																																										0.35
Consolidated total debt of subsidiaries to consolidated total capitalization ratio																																										10.00%
Repurchased of 10% Debentures	200,000,000	1,018,000,000
Interest rate on Note				4.625%	0.00%		5.125%		6.625%		4.30%		10.00%	6.10%		4.00%		7.30%		5.50%		5.375%		4.00%		6.30%		6.00%		5.50%		7.65%		7.375%		5.95%		6.625%		7.875%	8.125%						1800.00%	1700.00%
Net worth after tax																																										14,900,000,000
Line of Credit Facility, Amount Outstanding			$ 238,000,000																																											$ 0
Line of Credit Facility, Currency																																													20
Line of Credit Facility, Covenant Terms																																														194