Financial Instruments and Risk Management (Recognized Gains and Losses for Derivative Instruments Not Designated as Hedging Instruments) (Details) - Nondesignated [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss)	$ (21,257)	$ 7,370	$ (7,763)	$ 7,433
Commodity Derivative Contracts [Member] | Sales and other operating revenues [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss)	(47,738)	7,419	(34,549)	7,419
Foreign Exchange Derivative Contracts [Member] | Interest and other income (loss) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss)	$ 26,481	$ (49)	$ 26,786	$ 14