EMPLOYEE BENEFIT PLANS (Tables)

6 Months Ended

Jun. 30, 2011

EMPLOYEE BENEFIT PLANS [Abstract]

The components of net periodic benefit cost related to our defined benefit plans

	Pension Plans (a)						Other Postretirement Benefit Plans
	2011			2010			2011		2010
	(Thousands of Dollars)
For the three months ended June 30:
Components of net periodic benefit cost:
Service cost	$	3,121		$	2,846		$	260	$	226
Interest cost	720			558			222		208
Expected return on assets	(904		)	(579		)	—		—
Amortization of prior service credit	(4		)	(4		)	—		—
Amortization of net loss	121			136			18		21
Net periodic benefit cost	$	3,054		$	2,957		$	500	$	455
For the six months ended June 30:
Components of net periodic benefit cost:
Service cost	$	6,212		$	5,692		$	513	$	452
Interest cost	1,440			1,116			444		416
Expected return on assets	(1,808		)	(1,158		)	—		—
Amortization of prior service credit	(8		)	(8		)	—		—
Amortization of net loss	242			272			36		42
Net periodic benefit cost	$	6,078		$	5,914		$	993	$	910

(a) Includes amounts related to the pension plan, the excess pension plan and the supplemental executive retirement plan.