Benefit Plans and Other Postretirement Benefits (Tables)

3 Months Ended

Mar. 31, 2013

Benefit Plans and Other Postretirement Benefits [Abstract]

Components of Net Periodic Benefit Cost

Components of Net Periodic Benefit Cost

	Three Months Ended March 31
	2013			2012			2013			2012
(Thousands of Dollars)		Pension Benefits						Postretirement Health Care Benefits
Service cost	$	6,302		$	5,497		$	803		$	823
Interest cost		11,540			12,624			5,934			6,142
Expected return on plan assets		(15,955	)		(16,235	)		(7,307	)		(6,270	)
Amortization of transition obligation		-			-			196			2,751
Amortization of prior service (credit) cost		(266	)		57			(1,229	)		(1,288	)
Amortization of net loss		10,854			8,305			3,490			2,604
Net periodic benefit cost		12,475			10,248			1,887			4,762
Additional cost recognized due to the effects of regulation		-			-			-			973
Net benefit cost recognized for financial reporting	$	12,475		$	10,248		$	1,887		$	5,735