Debt - Long-Term Debt (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	6 Months Ended					6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 7.625% Senior Notes Due 2013	Jun. 30, 2013 6.625% Senior Notes Due 2019	Jun. 30, 2013 6.775% Senior Notes Due 2019	Jun. 30, 2013 2.75% Contingent Convertible Senior Notes Due 2035	Jun. 30, 2013 2.5% Contingent Convertible Senior Notes due 2037	Jun. 30, 2013 2.25% Contingent Convertible Senior Notes Due 2038	Jun. 30, 2013 Discount On Senior Notes	Dec. 31, 2012 Discount On Senior Notes	Jun. 30, 2013 Interest rate contract	Dec. 31, 2012 Interest rate contract	Dec. 31, 2012 Foreign currency contracts	Jun. 30, 2013 Term Loan [Member] Senior Secured Term Loan Due Two Thousand And Seventeen [Member]	Dec. 31, 2012 Term Loan [Member] Senior Secured Term Loan Due Two Thousand And Seventeen [Member]	Jun. 30, 2013 Senior Notes	Dec. 31, 2012 Senior Notes	Jul. 15, 2013 Senior Notes 7.625% Senior Notes Due 2013	Jun. 30, 2013 Senior Notes 7.625% Senior Notes Due 2013	Dec. 31, 2012 Senior Notes 7.625% Senior Notes Due 2013	Jun. 30, 2013 Senior Notes 9.5% Senior Notes Due 2015	Dec. 31, 2012 Senior Notes 9.5% Senior Notes Due 2015	Jun. 30, 2013 Senior Notes 3.25% Senior Notes due 2016	Dec. 31, 2012 Senior Notes 3.25% Senior Notes due 2016	Jun. 30, 2013 Senior Notes 6.25% Euro-Denominated Senior Notes Due 2017	Dec. 31, 2012 Senior Notes 6.25% Euro-Denominated Senior Notes Due 2017	Jun. 30, 2013 Senior Notes 6.25% Euro-Denominated Senior Notes Due 2017 Cross Currency Interest Rate Contract [Member]	Feb. 08, 2013 Senior Notes 6.25% Euro-Denominated Senior Notes Due 2017 Cross Currency Interest Rate Contract [Member]	May 31, 2011 Senior Notes 6.25% Euro-Denominated Senior Notes Due 2017 Cross Currency Interest Rate Contract [Member]	Jun. 30, 2013 Senior Notes 6.5% Senior Notes Due 2017	Dec. 31, 2012 Senior Notes 6.5% Senior Notes Due 2017	Jun. 30, 2013 Senior Notes 6.875% Senior Notes Due 2018	Dec. 31, 2012 Senior Notes 6.875% Senior Notes Due 2018	Jun. 30, 2013 Senior Notes 7.25% Senior Notes Due 2018	Dec. 31, 2012 Senior Notes 7.25% Senior Notes Due 2018	Jun. 30, 2013 Senior Notes 6.625% Senior Notes Due 2019	Dec. 31, 2012 Senior Notes 6.625% Senior Notes Due 2019	Jun. 30, 2013 Senior Notes 6.775% Senior Notes Due 2019	Dec. 31, 2012 Senior Notes 6.775% Senior Notes Due 2019	Jun. 30, 2013 Senior Notes 6.625% Senior Notes Due 2020	Dec. 31, 2012 Senior Notes 6.625% Senior Notes Due 2020	Jun. 30, 2013 Senior Notes 6.875% Senior Notes Due 2020	Dec. 31, 2012 Senior Notes 6.875% Senior Notes Due 2020	Jun. 30, 2013 Senior Notes 6.125% Senior Notes Due 2021	Dec. 31, 2012 Senior Notes 6.125% Senior Notes Due 2021	Jun. 30, 2013 Senior Notes 5.375% Senior Notes due 2021 [Member]	Dec. 31, 2012 Senior Notes 5.375% Senior Notes due 2021 [Member]	Jun. 30, 2013 Senior Notes 5.75% Senior Notes due 2023 [Member]	Dec. 31, 2012 Senior Notes 5.75% Senior Notes due 2023 [Member]	Jun. 30, 2013 Senior Notes 2.75% Contingent Convertible Senior Notes Due 2035	Dec. 31, 2012 Senior Notes 2.75% Contingent Convertible Senior Notes Due 2035	Jun. 30, 2013 Senior Notes 2.5% Contingent Convertible Senior Notes due 2037	Dec. 31, 2012 Senior Notes 2.5% Contingent Convertible Senior Notes due 2037	Jun. 30, 2013 Senior Notes 2.25% Contingent Convertible Senior Notes Due 2038	Dec. 31, 2012 Senior Notes 2.25% Contingent Convertible Senior Notes Due 2038	Jun. 30, 2013 Revolving Credit Facility [Member] Corporate Revolving Bank Credit Facility	Dec. 31, 2012 Revolving Credit Facility [Member] Corporate Revolving Bank Credit Facility	Jun. 30, 2013 Revolving Credit Facility [Member] Oilfield Services Revolving Bank Credit Facility	Dec. 31, 2012 Revolving Credit Facility [Member] Oilfield Services Revolving Bank Credit Facility
Long-Term Debt Instrument [Line Items]
Long-term Debt, Gross	$ 13,057	$ 12,620							$ (404)	$ (465)	$ 16	$ 20		$ 2,000	$ 2,000				$ 247	$ 464	$ 1,265	$ 1,265	$ 500	$ 0	$ 447	$ 454	$ 447			$ 660	$ 660	$ 97	$ 474	$ 669	$ 669	$ 650	$ 650	$ 0	$ 1,300	$ 1,300	$ 1,300	$ 500	$ 500	$ 1,000	$ 1,000	$ 700	$ 0	$ 1,100	$ 0	$ 396	$ 396	$ 1,168	$ 1,168	$ 347	$ 347	$ 0	$ 0	$ 399	$ 418
Current maturities of long-term debt, net	0	(463)
Long-term Debt, Excluding Current Maturities	13,057	12,157
Debt Instrument, Unamortized Discount														$ 36	$ 40	$ 340	$ 376		$ 1
Derivative, Forward Exchange Rate													1.3193														1.3010		1.3325
Debt Instrument Interest Rate Stated Percentage			7.625%	6.625%	6.775%													7.625%	7.625%		9.50%		3.25%				6.25%	6.25%		6.50%		6.875%		7.25%		6.625%		6.775%		6.625%		6.875%		6.125%		5.375%		5.75%		2.75%		2.50%		2.25%
Percentage Of Principal Amount Of Notes For Repurchase Requirement Of Contingent Convertible Senior Notes	100.00%
Debt Instrument, Convertible, Terms of Conversion Feature	5
Common Stock Price Conversion Thresholds						$ 48.31	$ 63.62	$ 107.01
Debt Instrument, Date of First Required Payment						May 14, 2016	Nov. 14, 2017	Jun. 14, 2019