Capital Stock Summary of RSU and PSU Activity (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Restricted Stock Units (RSUs) [Member]
Shares, Nonvested at Janaury 1, 2011	0.8
Shares, Granted	0.9
Shares, Vested	(0.3)
Shares, Cancelled	(0.2)
Shares, Nonvested at December 31, 2011	1.2	0.8
Weighted Average Grant Date Fair Value, Outstanding at January 1, 2011	$ 49.89
Weighted Average Grant Date Fair Value, Granted	$ 56.49	$ 51.06
Weighted Average Grant Date Fair Value, Vested	$ 49.67
Weighted Average Grant Date Fair Value, Cancelled	$ 53.54
Weighted Average Grant Date Fair Value, Outstanding December 31, 2011	$ 54.17	$ 49.89
Performance Stock Unit (PSUs) [Member]
Shares, Granted	0.1
Shares, Nonvested at December 31, 2011	0.1
Weighted Average Grant Date Fair Value, Granted	$ 59.70
Weighted Average Grant Date Fair Value, Cancelled	$ 59.70
Weighted Average Grant Date Fair Value, Outstanding December 31, 2011	$ 59.70