Benefit Plans and Other Postretirement Benefits (Tables)

9 Months Ended

Sep. 30, 2012

Benefit Plans and Other Postretirement Benefits [Abstract]

Components of Net Periodic Benefit Cost

Components of Net Periodic Benefit Cost

	Three Months Ended Sept. 30
	2012			2011			2012			2011
(Thousands of Dollars)		Pension Benefits						Postretirement Health Care  Benefits
Service cost	$	5,679		$	4,432		$	706		$	906
Interest cost		12,776			13,059			6,131			7,097
Expected return on plan assets		(16,326	)		(16,988	)		(6,264	)		(6,990	)
Amortization of transition obligation		-			-			2,751			2,751
Amortization of prior service cost (credit)		57			56			(1,288	)		(728	)
Amortization of net loss		8,552			7,032			2,734			2,236
Net periodic benefit cost		10,738			7,591			4,770			5,272
Additional cost recognized due to the effects of regulation		-			-			972			972
Net benefit cost recognized for financial reporting	$	10,738		$	7,591		$	5,742		$	6,244

	Nine Months Ended Sept. 30
	2012			2011			2012			2011
(Thousands of Dollars)	Pension Benefits						Postretirement Health Care  Benefits
Service cost	$	17,039		$	13,295		$	2,119		$	2,719
Interest cost		38,329			39,176			18,395			21,293
Expected return on plan assets		(48,977	)		(50,961	)		(18,792	)		(20,971	)
Amortization of transition obligation		-			-			8,253			8,253
Amortization of prior service cost (credit)		171			167			(3,863	)		(2,185	)
Amortization of net loss		25,652			21,095			8,198			6,707
Net periodic benefit cost		32,214			22,772			14,310			15,816
Additional cost recognized due to the effects of regulation		-			-			2,918			2,918
Net benefit cost recognized for financial reporting	$	32,214		$	22,772		$	17,228		$	18,734