Earnings per share (Tables)

12 Months Ended

Dec. 31, 2011

Earnings per share [Abstract]

Computation for basic and diluted earnings per share

	2011		2010		2009
Income (Numerator):
Net income for basic and diluted EPS	$	3,683	$	4,627	$	4,605
Shares (Denominator):
Weighted-average shares for basic EPS		905		960		1,016
Effect of dilutive securities		7		5		5
Weighted-average shares for diluted EPS		912		965		1,021
Basic EPS	$	4.07	$	4.82	$	4.53
Diluted EPS	$	4.04	$	4.79	$	4.51