Debt - Bank Credit Facilities Narrative (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Long-Term Debt Instrument [Line Items]
Long-term Debt, Gross	$ 12,969,000,000	$ 12,886,000,000
Corporate Revolving Bank Credit Facility
Long-Term Debt Instrument [Line Items]
Borrowing capacity	4,000,000,000
Interest Rate In Addition To Federal Funds Rate	0.50%
Line of Credit Facility, Commitment Fee Percentage	0.50%
Long-term Debt, Gross	0	0
Line of Credit Facility, Amount Outstanding	0
Corporate Revolving Bank Credit Facility | Minimum
Long-Term Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage Rate Range, Minimim	1.50%
Debt Outstanding Principal Amount	50,000,000
Corporate Revolving Bank Credit Facility | Maximum
Long-Term Debt Instrument [Line Items]
Debt Instrument, Interest Rage, Effective Percentage Rate Range, Maximum	2.25%
Long-term Debt	125,000,000
Corporate Revolving Bank Credit Facility | Union Bank N.A. | Minimum
Long-Term Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage Rate Range, Minimim	0.50%
Corporate Revolving Bank Credit Facility | Union Bank N.A. | Maximum
Long-Term Debt Instrument [Line Items]
Debt Instrument, Interest Rage, Effective Percentage Rate Range, Maximum	1.25%
Oilfield Services Revolving Bank Credit Facility
Long-Term Debt Instrument [Line Items]
Borrowing capacity	500,000,000
Interest Rate In Addition To Federal Funds Rate	0.50%
Line Of Credit Facility Extended Borrowing Capacity	900,000,000
Debt Instrument Interest Rate In Addition To Eurodollar Rate	1.00%
Acceleration of Principal Amount Due, Credit Facility	50,000,000
Long-term Debt, Gross	464,000,000	405,000,000
Line of Credit Facility, Amount Outstanding	464,000,000
Oilfield Services Revolving Bank Credit Facility | In Excess
Long-Term Debt Instrument [Line Items]
Line of Credit Facility, Amount Outstanding	$ 15,000,000
Oilfield Services Revolving Bank Credit Facility | Bank Of America N.A.
Long-Term Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage Rate Range, Minimim	1.00%
Debt Instrument, Interest Rage, Effective Percentage Rate Range, Maximum	1.75%
Oilfield Services Revolving Bank Credit Facility | Bank Of America N.A. | Minimum
Long-Term Debt Instrument [Line Items]
Line of Credit Facility, Commitment Fee Percentage	0.375%
Percentage above LIBOR rate	2.00%
Oilfield Services Revolving Bank Credit Facility | Bank Of America N.A. | Maximum
Long-Term Debt Instrument [Line Items]
Line of Credit Facility, Commitment Fee Percentage	0.50%
Percentage above LIBOR rate	2.75%