Employee And Retiree Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2013

Employee And Retiree Benefit Plans [Abstract]

Summary Of Components Of Net Periodic Benefit Expense

	Years ended December 31,
							Other Postretirement
	Pension Benefits						Benefits
(Thousands of dollars)	2013		2012		2011		2013		2012		2011
Service cost	$	3,401	$	4,227	$	5,482	$	1,447	$	1,770	$	2,708
Interest cost		2,717		4,252		6,535		983		1,454		3,023
Expected return on plan assets		(2,794)		(3,860)		(5,840)		-		-		-
Amortization of prior service cost (benefits)		53		90		166		(7)		(10)		(73)
Recognized actuarial loss		2,108		2,986		2,685		363		369		1,174
Termination benefits expense		-		-		695				-		-
Curtailment expense		-		-		821				-		(285)
Net periodic benefit expense	$	5,485	$	7,695	$	10,544	$	2,786	$	3,583	$	6,547

Summary Of Weighted-Average Assumptions Used In The Measurement Of Net Periodic Benefit Expense

	Net Periodic Benefit Expenses
	Pension Benefits Year				Postretirement Benefits Year
	2012		2011		2012		2011
Discount rate		4.87%		5.50%		4.87%		5.50%
Expected return on plan assets		6.50%		6.50%		0%		0%
Rate of compensation increase		4.20%		4.16%		0%		0%