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
							Postretirement Health
(Thousands of Dollars)	Pension Benefits						Care Benefits
Service cost	$	2,127		$	1,896		$	302		$	254
Interest cost		4,920			5,087			745			684
Expected return on plan assets		(6,217	)		(6,559	)		(674	)		(754	)
Amortization of transition obligation		-			-			387			418
Amortization of prior service cost (credit)		359			377			(37	)		(13	)
Amortization of net loss		3,265			2,576			345			216
Net periodic benefit cost		4,454			3,377			1,068			805
Cost not recognized due to the effects of regulation		(1,075	)		(575	)		-			-
Net benefit cost recognized for financial reporting	$	3,379		$	2,802		$	1,068		$	805

	Six Months Ended June 30
	2012			2011			2012			2011
							Postretirement Health
(Thousands of Dollars)	Pension Benefits						Care Benefits
Service cost	$	4,260		$	3,845		$	630		$	546
Interest cost		9,800			10,018			1,416			1,361
Expected return on plan assets		(12,464	)		(13,158	)		(1,351	)		(1,503	)
Amortization of transition obligation		-			-			773			835
Amortization of prior service cost (credit)		719			753			(74	)		(26	)
Amortization of net loss		6,407			4,523			628			428
Net periodic benefit cost		8,722			5,981			2,022			1,641
Cost not recognized due to the effects of regulation		(2,150	)		(1,150	)		-			-
Net benefit cost recognized for financial reporting	$	6,572		$	4,831		$	2,022		$	1,641