Benefits (Tables)

12 Months Ended

Dec. 31, 2011

Benefits (Tables) [Abstract]

Details about pension and OPEB plans

The following table presents details about our pension and OPEB plans:

	Pension						OPEB
	2011			2010			2011			2010
	(Millions of Dollars)
Change in Benefit Obligation
Benefit Obligation at January 1	$	1,222.8		$	1,160.7		$	368.3		$	374.7
Service cost	15.9			23.7			10.4			11.2
Interest cost	67.6			68.4			20.8			21.2
Participants' contributions	—			—			11.6			6.5
Plan amendments	—			—			0.4			0.3
Actuarial loss (gain)	98.0			53.4			7.6			(23.8		)
Curtailments	—			—			—			(1.0		)
Gross benefits paid	(73.7		)	(83.4		)	(30.3		)	(21.8		)
Federal subsidy on benefits paid	N/A			N/A			0.9			1.0
Benefit Obligation at December 31	$	1,330.6		$	1,222.8		$	389.7		$	368.3
Change in Plan Assets
Fair Value at January 1	$	1,059.5		$	1,026.0		$	216.7		$	202.6
Actual earnings on plan assets	33.8			110.1			9.0			24.5
Employer contributions	242.9			6.8			48.4			4.9
Participants' contributions	—			—			11.6			6.5
Gross benefits paid	(73.7		)	(83.4		)	(30.3		)	(21.8		)
Fair Value at December 31	$	1,262.5		$	1,059.5		$	255.4		$	216.7
Net Liability	$	68.1		$	163.3		$	134.3		$	151.6

Amounts recognized in Consolidated Balance Sheets

Amounts recognized in our Consolidated Balance Sheets as of December 31 related to the funded status of the benefit plans consisted of:

	Pension				OPEB
	2011		2010		2011		2010
	(Millions of Dollars)
Other deferred charges	$	—	$	—	$	20.3	$	38.3
Other long-term liabilities	68.1		163.3		154.6		189.9
Net liability	$	68.1	$	163.3	$	134.3	$	151.6

Amounts not yet been recognized in net periodic benefit cost

The following table shows the amounts that have not yet been recognized in our net periodic benefit cost as of December 31 and are recorded as a regulatory asset on our balance sheet:

	Pension				OPEB
	2011		2010		2011			2010
	(Millions of Dollars)
Net actuarial loss	$	633.4	$	521.0	$	108.1		$	98.9
Prior service costs (credits)	14.4		16.7		(6.1		)	(8.5		)
Transition obligation	—		—		0.3			0.6
Total	$	647.8	$	537.7	$	102.3		$	91.0

Components of net periodic pension and OPEB costs

The components of net periodic pension and OPEB costs for the years ended December 31 are as follows:

	Pension									OPEB
	2011			2010			2009			2011			2010			2009
	(Millions of Dollars)
Net Periodic Benefit Cost
Service cost	$	15.9		$	23.7		$	23.3		$	10.4		$	11.2		$	8.7
Interest cost	67.6			68.4			72.3			20.8			21.2			20.5
Expected return on plan assets	(82.1		)	(78.2		)	(95.4		)	(16.9		)	(14.3		)	(13.6		)
Amortization of:
Transition obligation	—			—			—			0.3			0.3			0.3
Prior service cost (credit)	2.2			2.2			2.2			(1.9		)	(11.9		)	(12.6		)
Actuarial loss	34.0			26.8			18.9			6.2			10.8			8.9
Curtailment (gain)	—			—			—			—			(0.4		)	—
Net Periodic Benefit Cost	$	37.6		$	42.9		$	21.3		$	18.9		$	16.9		$	12.2

In addition to the costs above, in 2011 we recorded net pension costs of less than $0.04 per share related to the settlement of pension litigation. See Note R -- Commitments and Contingencies in this report. The charges were after considering insurance and reserves established in the prior year.

	Pension			OPEB
	2011	2010	2009	2011	2010	2009
Weighted-Average assumptions used to
determine benefit obligations as of Dec. 31
Discount rate	5.05%	5.60%	6.05%	5.20%	5.70%	5.75%
Rate of compensation increase	4.0%	4.0%	4.0%	N/A	N/A	N/A
Weighted-Average assumptions used to
determine net cost for year ended Dec. 31
Discount rate	5.60%	6.05%	6.50%	5.70%	5.75%	6.50%
Expected return on plan assets	7.25%	7.25%	8.25%	7.50%	7.50%	8.25%
Rate of compensation increase	4.0%	4.0%	4.0%	N/A	N/A	N/A

Assumed health care cost trend rates as of Dec. 31	2011	2010	2009
Health care cost trend rate assumed for next year (Pre 65 / Post 65)	8.0%/12%	7.5%/16%	7.5%/20%
Rate that the cost trend rate gradually adjusts to	5.0%	5.0%	5.0%
Year that the rate reaches the rate it is assumed to remain at (Pre 65 / Post 65)	2017/2017	2015/2016	2015/2016

A one-percentage-point change in assumed health care cost trend rates effects

A one-percentage-point change in assumed health care cost trend rates would have the following effects:

	1% Increase		1% Decrease
	(Millions of Dollars)
Effect on
Post-retirement benefit obligation	$	31.9	$	(26.8	)
Total of service and interest cost components	$	3.8	$	(3.1	)

Summary of fair value of plan assets by asset category within fair value hierarchy

The following table summarizes the fair value of our pension plan assets by asset category within the fair value hierarchy (for further level information, see Note M):

	As of December 31, 2011
Asset Category - Pension	Level 1		Level 2		Level 3		Total
	(Millions of Dollars)
Cash and Cash Equivalents	$	8.5	$	—	$	—	$	8.5
Equities:
U.S. Equity	455.1		—		—		455.1
International Equity	100.4		33.9		—		134.3
Fixed Income
Short, Intermediate and Long-term Bonds (a)
U.S. Bonds	76.9		502.8		—		579.7
International Bonds	40.9		44.0		—		84.9
Total	$	681.8	$	580.7	$	—	$	1,262.5

	As of December 31, 2010
Asset Category - Pension	Level 1		Level 2		Level 3		Total
	(Millions of Dollars)
Cash and Cash Equivalents	$	21.1	$	—	$	—	$	21.1
Equities:
U.S. Equity	217.2		247.5		—		464.7
International Equity	81.1		21.6		—		102.7
Fixed Income
Short, Intermediate and Long-term Bonds (a)
U.S. Bonds	49.7		361.5		—		411.2
International Bonds	31.8		28.0		—		59.8
Total	$	400.9	$	658.6	$	—	$	1,059.5

(a) This category represents investment grade bonds of U.S. and foreign issuers denominated in U.S. dollars from diverse industries.

The following table summarizes the fair value of our OPEB plan assets by asset category within the fair value hierarchy:

	As of December 31, 2011
Asset Category - OPEB	Level 1		Level 2		Level 3		Total
	(Millions of Dollars)
Cash and Cash Equivalents	$	2.4	$	—	$	—	$	2.4
Equities:
U.S. Equity	113.6		—		—		113.6
International Equity	32.1		2.3		—		34.4
Fixed Income:
Short, Intermediate and Long-term Bonds (a)
U.S. Bonds	8.2		83.0		—		91.2
International Bonds	8.7		5.1		—		13.8
Total	$	165.0	$	90.4	$	—	$	255.4

	As of December 31, 2010
Asset Category - OPEB	Level 1		Level 2		Level 3		Total
	(Millions of Dollars)
Cash and Cash Equivalents	$	1.5	$	—	$	—	$	1.5
Equities:
U.S. Equity	41.6		80.1		—		121.7
International Equity	5.2		1.4		—		6.6
Fixed Income:
Short, Intermediate and Long-term Bonds (a)
U.S. Bonds	21.8		59.4		—		81.2
International Bonds	2.0		3.7		—		5.7
Total	$	72.1	$	144.6	—		$	216.7

(a) This category represents investment grade bonds of U.S. and foreign issuers denominated in U.S. dollars from diverse industries.

Employer contributions to defined benefit plan

Cash Flows:   

Employer	Pension
Contributions	Qualified		Non-Qualified		OPEB
	(Millions of Dollars)
2009	$	270.0	$	5.8	$	24.3
2010	$	—	$	6.8	$	4.9
2011	$	236.4	$	6.5	$	48.4

Expected benefit payments in future

The following table identifies our expected benefit payments over the next 10 years:

Year	Pension		Gross OPEB		Expected Medicare Part D Subsidy
	(Millions of Dollars)
2012	$	110.1	$	20.2	$	(0.9	)
2013	$	101.3	$	20.8	$	—
2014	$	104.4	$	22.2	$	—
2015	$	103.6	$	23.5	$	—
2016	$	103.9	$	24.7	$	—
2017-2021	$	535.2	$	136.4	$	—