Income Taxes (Details 6) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income Taxes
Percentage of Likelihood for Realization of Benefit Upon Ultimate Settlement	50.00%
Reconciliation of the beginning and ending amount of unrecognized tax benefits
Balance at year beginning	$ 95.8	$ 96.9	$ 86.8
Increase in prior year tax positions	1.2		56.4
Decrease in prior year tax positions		(6.1)
Tax positions taken during the current year	(20.4)	5.4	16.4
Lapse in statute of limitations	(10.5)		(1.2)
Settlements with tax authorities	(0.6)	(0.4)	(61.5)
Balance at year end	65.5	95.8	96.9
Unrecognized tax benefit recognition including interest and penalties, if recognized, would effect income tax expense	16.4
Tax positions for which ultimate deductibility is highly certain but the timing of deductibility is uncertain	49.1
Interest (benefit) expense, net of any tax benefit	0.6	1.9	(4.0)
Accrued interest, net of any tax benefit	6.8	6.2
Permanent Differences
Reconciliation of the beginning and ending amount of unrecognized tax benefits
Balance at year beginning	14.5	13.9	61.4
Increase in prior year tax positions		0.5	7.2
Decrease in prior year tax positions	(0.9)
Tax positions taken during the current year		0.4
Lapse in statute of limitations	(3.4)		(1.0)
Settlements with tax authorities	(0.6)	(0.3)	(53.7)
Balance at year end	9.6	14.5	13.9
Temporary Differences
Reconciliation of the beginning and ending amount of unrecognized tax benefits
Balance at year beginning	75.1	78.7	17.1
Increase in prior year tax positions	0.1		46.1
Decrease in prior year tax positions		(8.5)
Tax positions taken during the current year	(20.4)	5.0	16.4
Lapse in statute of limitations	(5.7)
Settlements with tax authorities		(0.1)	(0.9)
Balance at year end	49.1	75.1	78.7
Interest and Penalties
Reconciliation of the beginning and ending amount of unrecognized tax benefits
Balance at year beginning	6.2	4.3	8.3
Increase in prior year tax positions	2.0	1.9	3.1
Lapse in statute of limitations	(1.4)		(0.2)
Settlements with tax authorities			(6.9)
Balance at year end	$ 6.8	$ 6.2	$ 4.3