Debt - Bank Credit Facilities Narrative (Details) (USD $)	3 Months Ended				12 Months Ended
	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2013
Long-Term Debt Instrument [Line Items]
Long-term Debt					$ 13,230,000,000
Long-term Debt, Gross			12,620,000,000		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%
Increase to Applicable Margin, Credit Facility					0.25%
Credit Facility Borrowing Capacity Margin					50.00%
Minimum Collateral Value, Credit Facility					75,000,000
Debt Instrument, Covenant Description	4.00 to 1.00	4.75 to 1.00	5.00 to 1.00	6.00 to 1.00
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			418,000,000		405,000,000
Line of Credit Facility, Amount Outstanding					405,000,000
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%