Common Equity (Tables)

3 Months Ended

Mar. 31, 2014

Stockholders' Equity Note [Abstract]

Assumptions for valuing options using binomial option pricing model

	2014			2013
Non-qualified stock options granted year to date	864,860			1,365,970
Estimated fair value per non-qualified stock option	$	4.18		$	3.45
Assumptions used to value the options using a binomial option pricing model:
Risk-free interest rate	0.1% - 3.0%			0.1% - 1.9%
Dividend yield	3.8		%	3.7		%
Expected volatility	18.0		%	18.0		%
Expected forfeiture rate	2.0		%	2.0		%
Expected life (years)	5.8			5.9

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, 2014	7,688,843		$	26.92
Granted	864,860		$	41.03
Exercised	(649,481	)	$	21.71
Forfeited	(6,385	)	$	36.55
Outstanding as of March 31, 2014	7,897,837		$	28.89	5.8	$	139.5
Exercisable as of March 31, 2014	5,070,842		$	23.83	4.2	$	115.2

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)
$17.10  to  $21.11	1,615,342	$	20.68	4.1	1,615,342	$	20.68	4.1
$23.88  to  $29.35	3,253,295	$	24.68	4.0	3,253,295	$	24.68	4.0
$34.88  to  $41.03	3,029,200	$	37.78	8.8	202,205	$	35.35	7.9
	7,897,837	$	28.89	5.8	5,070,842	$	23.83	4.2

Non-vested options

			Weighted-Average
Non-Vested Stock Options	Number of Options		Fair Value
Non-vested as of January 1, 2014	2,289,400		$	3.38
Granted	864,860		$	4.18
Vested	(320,880	)	$	3.21
Forfeited	(6,385	)	$	3.41
Non-vested as of March 31, 2014	2,826,995		$	3.65

Restricted stock activity

			Weighted-Average
Restricted Shares	Number of Shares		Grant Date Fair Value
Outstanding as of January 1, 2014	98,226
Granted	51,873		$	40.98
Released	(46,228	)	$	34.31
Forfeited	(1,098	)	$	38.04
Outstanding as of March 31, 2014	102,773