Equity (Details 5) (Stock options, USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 Y	Dec. 31, 2011	Dec. 31, 2010
Stock options
Shares
Outstanding at the beginning of the period (in shares)	3.8	5.1	6.6
Granted (in shares)	0.1	0.8	0.2
Exercised (in shares)	(1.8)	(1.5)	(0.5)
Cancelled (in shares)	(0.4)	(0.6)	(1.2)
Outstanding at the ending of the period (in shares)	1.7	3.8	5.1
Exercisable at the end of the period (in shares)	1.2
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 40.42	$ 41.39	$ 42.50
Granted (in dollars per share)	$ 53.77	$ 47.51	$ 42.54
Exercised (in dollars per share)	$ 35.58	$ 41.15	$ 32.07
Cancelled (in dollars per share)	$ 44.68	$ 56.84	$ 51.64
Outstanding at the ending of the period (in dollars per share)	$ 45.08	$ 40.42	$ 41.39
Exercisable at the end of the period (in dollars per share)	$ 43.85
Weighted Average Remaining Contractual Life (in years)
Outstanding at the end of the period (in years)	7.4
Exercisable at the end of the period (in years)	6.8
Aggregate Intrinsic Value
Exercised	$ 32.9	$ 13.2	$ 5.3