Accounts Receivable (Tables)

12 Months Ended

Dec. 31, 2011

Accounts Receivable

Summary of trade accounts receivable

	2011			2010
Gross accounts receivable	$	288.4		$	238.0
Allowance for doubtful accounts		(5.6	)		(5.1	)
Accounts receivable, net	$	282.8		$	232.9

Summary of activity in the allowance for doubtful accounts

	Balance at Beginning of Period		Additions Charged to Expense		Deductions Amounts Written Off			Balance at End of Period
2011	$	5.1		0.9		(0.4	)	$	5.6
2010		5.4		0.3		(0.6	)		5.1
2009		5.4		1.2		(1.2	)		5.4