Equity (Narrative) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	0 Months Ended		4 Months Ended	9 Months Ended	12 Months Ended				1 Months Ended		3 Months Ended	1 Months Ended
	Apr. 02, 2013	Mar. 25, 2013	Jul. 25, 2013	Sep. 30, 2013	Dec. 31, 2011 agreements	Sep. 30, 2013 2011 repurchase program	Sep. 30, 2013 First ASR agreement	Sep. 30, 2013 Second ASR agreement	Feb. 28, 2012 Uncollared ASR agreement	Dec. 31, 2011 Uncollared ASR agreement	Sep. 30, 2013 Uncollared ASR agreement	Apr. 30, 2012 Capped ASR agreement	Dec. 31, 2011 Capped ASR agreement
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock repurchase program number of shares authorized to be repurchased (in shares)						50.0
Maximum number of shares authorized for repurchase under stock repurchase plan as percentage of outstanding common stock						17.00%
Remaining shares available under repurchase program (in shares)						1.9
Repurchase of additional shares (in shares)		$ 500			$ 500
Repurchase of shares at a per share price (in shares)							$ 250	$ 250
Shares received on initial delivery (in shares)										5.0	7.2		5.0
Additional shares received (in shares)	1.4		0.7						0.8			0.1
Accelerated share repurchases, final price paid (in dollars per share)			$ 53.7995
Accelerated share repurchases, cumulative shares repurchased (in shares)			9.3
Accelerated share repurchase program, number of agreements entered (in agreements)					2
Interest in joint venture minimum percentage				20.00%
Agreement terms, change of control, put option for minority interest ownership, effective period				15 days