Financial Instruments and Risk Management (Tables)

3 Months Ended

Mar. 31, 2015

Financial Instruments and Risk Management [Abstract]

Fair Value of Derivative Instruments Not Designated as Hedging Instruments

	March 31, 2015			December 31, 2014
(Thousands of dollars)	Asset (Liability) Derivatives			Asset (Liability) Derivatives
Type of Derivative Contract	Balance Sheet Location	Fair Value		Balance Sheet Location	Fair Value
Commodity	Accounts receivable	$	–	Accounts receivable	$	23,168
Foreign exchange	Accounts receivable		38	Accounts payable		(25)

Recognized Gains and Losses for Derivative Instruments Not Designated as Hedging Instruments

			Gain (Loss)
		Three Months Ended
(Thousands of dollars)	Statement of Income	March 31,
Type of Derivative Contract	Location		2015	2014
Commodity	Sales and other operating revenues	$	–	(18,414)
Foreign exchange	Interest and other income		63	3,436
		$	63	(14,978)

Carrying Value of Assets and Liabilities Recorded at Fair Value on Recurring Basis

	March 31, 2015					December 31, 2014
(Thousands of dollars)	Level 1		Level 2	Level 3	Total	Level 1	Level 2	Level 3	Total
Assets:
Foreign currency exchange         derivative contracts		–	38	–	38	–	–	–	–
Commodity derivative         contracts		–	–	–	–	–	23,168	–	23,168
	$	–	38	–	38	–	23,168	–	23,168
Liabilities:
Nonqualified employee         savings plans	$	(14,696)	–	–	(14,696)	(14,408)	–	–	(14,408)
Foreign currency exchange         derivative contracts		–	–	–	–	–	(25)	–	(25)
	$	(14,696)	–	–	(14,696)	(14,408)	(25)	–	(14,433)