Incentive Stock Plans Performance Share Units (Details) (Performance Shares [Member], USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Valuation method	Monte Carlo simulation model
Unrecognized compensation cost	$ 9.1
Weighted average period for recognition (years)	1 year 8 months 12 days
Common shares of Company stock reserved for performance shares	337,360		470,820		606,180
Weighted average fair value of performance share units granted	$ 56.36		$ 51.57		$ 39.25
Intrinsic value of outstanding performance share units	36.3	[1]	46.0	[1]	40.3	[1]
Fair value of performance shares vested	22.2		9.9		19.7
Cash used to pay the minimum witholding tax requirements in lieu of receiving common shares	$ 7.2		$ 7.1		$ 5.3
Outstanding Performance Share units	700,825		1,030,075
Number of units granted	168,680
Number of units distributed	(488,570)
Number of units cancelled or adjusted	(9,360)
Weighted average grant date fair value of outstanding Performance Share units	$ 47.23		$ 33.73
Weighted average grant date fair value of units distributed	$ 21.76
Weighted average grant date fair value of units cancelled or adjusted	$ 45.08
Risk-free rate, description	The risk-free rate was based on the 3-year U.S. treasury rate on the date of the award.
Dividend yield, description	The dividend yield was not used to calculate fair value as all awards granted after January 1, 2010 receive dividend equivalents.
Expected volatility	36.90%		51.30%		51.70%
Risk-free rate	0.40%		1.00%		1.40%

[1] Intrinsic value of outstanding performance share units is based on the market price of the Company's stock at December 31, 2012.