Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2011

Summary of Significant Accounting Policies

Computation of basic and diluted earnings per share

($ in millions, except per share data)	2011		2010		2009
Numerator:
Net income	$	788	$	928	$	854
Denominator:
Weighted average common shares outstanding		520.7		540.3		539.6
Effect of dilutive potential common shares:
Stock options		1.8		2.0		1.3
Restricted stock units (non-participating)		0.6		0.2		—
Weighted average common and dilutive potential common shares outstanding		523.1		542.5		540.9
Earnings per share – Basic	$	1.51	$	1.72	$	1.58
Earnings per share – Diluted	$	1.51	$	1.71	$	1.58