Income Tax Matters, Effective Tax Rate Reconciliation (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011		Dec. 31, 2010
Reconciliation between effective income tax provision and statutory income tax provision:
Amount of federal income tax provision based on the statutory rate	$ (48.9)	$ (14.5)		$ (8.8)
Decrease (increase) in federal valuation allowances	0.1	0		(0.2)
Non-deductible compensation expense	(0.4)	(1.1)		(0.6)
Non-deductible expense	(0.3)	(0.4)		(0.3)
State income taxes, net of federal benefit	(3.8)	(0.8)	[1]	(4.7)	[1]
Foreign income tax benefit	(0.5)	0.6		1.5
Income tax provision	(53.8)	(16.2)		(13.1)
Valuation Allowance [Line Items]
(Decrease) Increase in valuation allowance	(0.1)	(1.3)		2.1
Increase in state and local income tax provision relating to state NOLs	5.9	1.2		7.3
Unused state net operating losses
Valuation Allowance [Line Items]
(Decrease) Increase in valuation allowance		(1.2)		1.9
Increase in state and local income tax provision relating to state NOLs				$ 2.3

[1] State income taxes of $0.8 in 2011 includes a $1.2 decrease in the valuation allowance relating to certain unused state net operating losses expected to expire.State income taxes of $4.7 in 2010 primarily consists of (i) a $1.9 increase in the valuation allowance relating to certain unused state net operating losses expected to expire and (ii) a $2.3 increase in the income tax provision from a reduction in the state deferred tax asset relating to a decrease in state net operating losses resulting from lower state apportionment factors in various states.