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	$	21,853		$	20,548		$	922		$	1,097
Interest cost		39,365			40,791			9,551			10,492
Expected return on plan assets		(52,072	)		(55,514	)		(7,094	)		(8,013	)
Amortization of transition obligation		-			-			3,580			3,611
Amortization of prior service cost (credit)		5,267			5,633			(1,888	)		(1,233	)
Amortization of net loss		27,467			20,527			4,487			3,304
Net periodic benefit cost		41,880			31,985			9,558			9,258
Cost not recognized and additional cost recognized due to the effects of regulation		(10,158	)		(10,715	)		973			973
Net benefit cost recognized for financial reporting	$	31,722		$	21,270		$	10,531		$	10,231

	Six Months Ended June 30
	2012			2011			2012			2011
							Postretirement Health
(Thousands of Dollars)	Pension Benefits						Care Benefits
Service cost	$	43,182		$	38,660		$	2,102		$	2,412
Interest cost		78,088			80,706			18,931			21,043
Expected return on plan assets		(103,548	)		(110,800	)		(14,205	)		(15,981	)
Amortization of transition obligation		-			-			7,160			7,222
Amortization of prior service cost (credit)		10,533			11,266			(3,776	)		(2,466	)
Amortization of net loss		53,785			39,256			8,452			6,647
Net periodic benefit cost		82,040			59,088			18,664			18,877
Cost not recognized and additional cost recognized due to the effects of regulation		(19,291	)		(18,600	)		1,946			1,946
Net benefit cost recognized for financial reporting	$	62,749		$	40,488		$	20,610		$	20,823