Earnings per share (Tables)

12 Months Ended

Dec. 31, 2012

Notes To Financial Statements [Abstract]

Earnings per share reconciliation

	Year ended December 31,		2012		2011		2010
Basic earnings per share		$	6.15	$	5.45	$	4.51
Diluted earnings per share		$	6.12	$	5.41	$	4.48
The following table provides a reconciliation between basic and diluted earnings per share:
In millions	Year ended December 31,		2012		2011		2010
Net income		$	2,680	$	2,457	$	2,104
Weighted-average shares outstanding			435.6		451.1		466.3
Effect of stock options			2.1		3.3		3.8
Weighted-average diluted shares outstanding			437.7		454.4		470.1