Common Equity (Tables)

3 Months Ended

Mar. 31, 2012

Common Equity (Tables) [Abstract]

Shares Repurchased [Table Text Block]

	Three Months Ended March 31
	2012			2011
	Shares	Cost		Shares	Cost
	(In Millions)
Under May 2011 share repurchase program	—	$	—	—	$	—
To fulfill exercised stock options and restricted stock awards	0.8	$	28.3	0.8	$	24.2
Total	0.8	$	28.3	0.8	$	24.2

Assumptions for valuing options using binomial option pricing model

	2012		2011
Risk-free interest rate	0.1% - 2.0%		0.2% - 3.4%
Dividend yield	3.9	%	3.9	%
Expected volatility	19.0	%	19.0	%
Expected forfeiture rate	2.0	%	2.0	%
Expected life (years)	5.9		5.5

Stock option activity

					Weighted-
					Average
			Weighted-		Remaining	Aggregate
	Number of		Average		Contractual Life	Intrinsic Value
Stock Options	Options		Exercise Price		(Years)	(Millions)
Outstanding as of January 1, 2012	10,638,750		$	21.65
Granted	938,770		$	34.88
Exercised	(718,669	)	$	18.01
Forfeited	(7,720	)	$	26.94
Outstanding as of March 31, 2012	10,851,131		$	23.03	5.7	$	131.8
Exercisable as of March 31, 2012	9,118,361		$	21.52	5.0	$	124.5

Stock options outstanding

	Options Outstanding				Options Exercisable
		Weighted-Average				Weighted-Average
				Remaining				Remaining
	Number of	Exercise		Contractual	Number of	Exercise		Contractual
Range of Exercise Prices	Options	Price		Life (Years)	Options	Price		Life (Years)
$12.71 to $19.74	2,750,199	$	17.81	2.9	2,750,199	$	17.81	2.9
$21.11 to $24.92	6,713,942	$	23.09	6.0	6,257,402	$	22.96	5.9
$29.35 to $34.88	1,386,990	$	33.09	9.4	110,760	$	32.59	9.3
	10,851,131	$	23.03	5.7	9,118,361	$	21.52	5.0

Non-vested options

			Weighted-Average
Non-Vested Stock Options	Number of Options		Fair Value
Non-vested as of January 1, 2012	3,103,770		$	3.78
Granted	938,770		$	3.34
Vested	(2,302,050	)	$	3.96
Forfeited	(7,720	)	$	3.25
Non-vested as of March 31, 2012	1,732,770		$	3.31

Restricted stock activity

			Weighted-Average
Restricted Shares	Number of Shares		Grant Date Fair Value
Outstanding as of January 1, 2012	192,558
Granted	94,959		$	34.46
Released	(72,660	)	$	33.09
Forfeited	(3,945	)	$	30.81
Outstanding as of March 31, 2012	210,912

Disclosure of Compensation Related Costs, Share-based Payments [Text Block]

	Three Months Ended March 31
	2012		2011
	(Millions of Dollars)
Performance units	$	11.8	$	1.0
Stock options	0.7		0.6
Restricted stock	0.8		0.5
Share-based compensation expense	$	13.3	$	2.1
Related Tax Benefit	$	5.3	$	0.8