Debt Bank Credit Facilities (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
Line of Credit Facility [Line Items]
Facility Structure	Senior secured revolving
Maturity Date	November 2016
Corporate Revolving Bank Credit Facility
Line of Credit Facility [Line Items]
Facility Structure	Senior secured revolving
Maturity Date	December 2015
Borrowing Capacity	$ 4,000
Amount Outstanding, Amount	0
Letters of Credit Outstanding, Amount	31
Oilfield Services Revolving Bank Credit Facility
Line of Credit Facility [Line Items]
Borrowing Capacity	500
Amount Outstanding, Amount	399
Letters of Credit Outstanding, Amount	$ 0