Stock-based compensation Stock-based compensation (Tables)

12 Months Ended

Dec. 31, 2012

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

Components of stock-based compensation expense recognized in the Consolidated Statements of Income

The following table reflects the components of stock-based compensation expense recognized in our Consolidated Statements of Income for the years ended December 31, 2012, 2011 and 2010 (in millions):

	2012			2011			2010
Stock options	$	59		$	85		$	124
RSUs	186			188			182
Performance units	117			68			47
Total stock-based compensation expense, pretax	362			341			353
Tax benefit from stock-based compensation expense	(134		)	(124		)	(120		)
Total stock-based compensation expense, net of tax	$	228		$	217		$	233

Weighted average assumptions used and the resulting weighted average grant date fair value of employee stock options

The weighted-average assumptions used in the option valuation model and the resulting weighted-average estimated grant date fair values of stock options were as follows for the years ended December 31, 2012, 2011 and 2010:

	2012			2011			2010
Closing price of our common stock on grant date	$	74.56		$	54.66		$	58.32
Expected volatility	22.2		%	23.5		%	28.0		%
Expected life (in years)	8.1			5.9			6.6
Risk-free interest rate	1.6		%	2.5		%	3.2		%
Expected dividend yield	2.1		%	2.0		%	0		%
Fair value of stock options granted	$	14.65		$	11.39		$	20.97

Stock options information

The following summarizes select information regarding our stock options during the year ended December 31, 2012:

	Options (in millions)		Weighted- average exercise price		Weighted- average remaining contractual life (years)	Aggregate intrinsic value (in millions)
Balance unexercised at December 31, 2011	34.2		$	59.11
Granted	0.1		$	74.56
Exercised	(20.9	)	$	60.67
Expired/forfeited	(1.1	)	$	63.97
Balance unexercised at December 31, 2012	12.3		$	56.09	4.9	$	371
Vested or expected to vest at December 31, 2012	12.2		$	56.10	4.9	$	367
Exercisable at December 31, 2012	6.3		$	56.59	3.1	$	187

Restricted stock units Information

The following summarizes select information regarding our RSUs during the year ended December 31, 2012:

	Units (in millions)		Weighted-average grant date fair value
Balance nonvested at December 31, 2011	9.0		$	52.64
Granted	3.9		$	72.99
Vested	(2.8	)	$	50.64
Forfeited	(0.7	)	$	58.38
Balance nonvested at December 31, 2012	9.4		$	61.14

Weighted average assumptions used and the resulting weighted average grant date fair value of performance units

The weighted-average assumptions used in these models and the resulting weighted-average grant date fair values of our performance units were as follows for the years ended December 31, 2012, 2011 and 2010:

	2012			2011			2010
Closing price of our common stock on grant date	$	68.75		$	51.67		$	56.90
Volatility	22.9		%	32.8		%	34.7		%
Risk-free interest rate	0.5		%	1.2		%	1.3		%
Expected dividend yield	2.2		%	0.1		%	0		%
Fair value of unit	$	78.21		$	49.50		$	62.06