Benefit Plans and Other Postretirement Benefits (Tables)

6 Months Ended

Jun. 30, 2012

Benefit Plans and Other Postretirement Benefits [Abstract]

Components of Net Periodic Benefit Cost

Components of Net Periodic Benefit Cost

	Three Months Ended June 30
	2012			2011			2012			2011
(Thousands of Dollars)	Pension Benefits						Postretirement Health Care Benefits
Service cost	$	5,863		$	4,409		$	590		$	815
Interest cost		12,929			13,203			6,122			6,961
Expected return on plan assets		(16,416	)		(17,011	)		(6,258	)		(7,012	)
Amortization of transition obligation		-			-			2,751			2,751
Amortization of prior service cost (credit)		57			56			(1,287	)		(729	)
Amortization of net loss		8,795			7,314			2,860			2,188
Net periodic benefit cost		11,228			7,971			4,778			4,974
Additional cost recognized due to the effects of regulation		-			-			973			973
Net benefit cost recognized for financial reporting	$	11,228		$	7,971		$	5,751		$	5,947

	Six Months Ended June 30
	2012			2011			2012			2011
(Thousands of Dollars)	Pension Benefits						Postretirement Health Care Benefits
Service cost	$	11,360		$	8,863		$	1,413		$	1,813
Interest cost		25,553			26,117			12,264			14,196
Expected return on plan assets		(32,651	)		(33,973	)		(12,528	)		(13,981	)
Amortization of transition obligation		-			-			5,502			5,502
Amortization of prior service cost (credit)		114			111			(2,575	)		(1,457	)
Amortization of net loss		17,100			14,063			5,464			4,471
Net periodic benefit cost		21,476			15,181			9,540			10,544
Additional cost recognized due to the effects of regulation		-			-			1,946			1,946
Net benefit cost recognized for financial reporting	$	21,476		$	15,181		$	11,486		$	12,490