EMPLOYEE BENEFIT PLANS (Tables)

9 Months Ended

Sep. 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 September 30:
Components of net periodic benefit cost:
Service cost	$	3,136		$	2,846		$	264	$	226
Interest cost	720			559			222		208
Expected return on assets	(904		)	(577		)	—		—
Amortization of prior service credit	(4		)	(4		)	—		—
Amortization of net loss	120			132			18		21
Net periodic benefit cost	$	3,068		$	2,956		$	504	$	455
For the nine months ended September 30:
Components of net periodic benefit cost:
Service cost	$	9,348		$	8,538		$	777	$	678
Interest cost	2,160			1,675			666		624
Expected return on assets	(2,712		)	(1,735		)	—		—
Amortization of prior service credit	(12		)	(12		)	—		—
Amortization of net loss	362			404			54		63
Net periodic benefit cost	$	9,146		$	8,870		$	1,497	$	1,365

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