Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2011

Significant Accounting Policies [Abstract]

Gain and losses recognized on the sale and disposal of property

The amount of gains and losses for the years ended December 31 was as follows:

(in millions)	2011			2010			2009
Gains on the sale of property	$	19.0		$	4.9		$	6.0
Losses on the sale and disposal of property		(2.8	)		(9.9	)		(11.9	)
Net gains (losses) on sale and disposal of property	$	16.2		$	(5.0	)	$	(5.9	)