Debt - Bank Credit Facilities Table (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014
Line of Credit Facility [Line Items]
Number Of Credit Facilities	2
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 as of March 31, 2014	0
Letters of credit outstanding as of March 31, 2014	23
Oilfield Services Revolving Bank Credit Facility
Line of Credit Facility [Line Items]
Facility structure	Senior secured revolving
Maturity date	November 2016
Borrowing capacity	500
Amount outstanding as of March 31, 2014	464
Letters of credit outstanding as of March 31, 2014	$ 0