VALUATION AND QUALIFYING ACCOUNTS

12 Months Ended

Dec. 31, 2012

VALUATION AND QUALIFYING ACCOUNTS

14. VALUATION AND QUALIFYING ACCOUNTS

The following table summarizes the activity and ending balances in our allowance for doubtful accounts and estimated revenue adjustments (amounts in millions):

Allowance for Doubtful Accounts

Year end	Balance at Beginning of Year		Provision for Doubtful Accounts (1)		Write-Offs			Balance at End of Year
2012	$	17.4	$	21.7	$	(18.1	)	$	21.0
2011		21.0		13.7		(17.3	)		17.4
2010		26.4		19.2		(24.6	)		21.0

(1) Includes $0.1 million, $0.2 million and $0.5 million from discontinued operations for the years ended December 31, 2012, 2011 and 2010, respectively.

Estimated Revenue Adjustments

Year end	Balance at Beginning of Year		Provision for Estimated Revenue Adjustments (1)		Write-Offs			Balance at End of Year
2012	$	6.8	$	10.6	$	(11.0	)	$	6.4
2011		6.5		12.1		(11.8	)		6.8
2010		8.7		7.0		(9.2	)		6.5

(1) Includes $0.2 million, $0.3 million and $0.5 million from discontinued operations for the years ended December 31, 2012, 2011 and 2010, respectively.