Fair Value Measurements Unobservable Inputs Rollforward (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 11.6	$ 26.3
Sale of ARS	19.7	(21.8)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net		(3.8)
Realized Investment Gains (Losses)	15.2	19.0	18.7
Included in other comprehensive income	(6.4)	(8.1)
Ending balance	0.7	11.6	26.3
The amount of total losses for the period included in net loss attributable to the fair value of changes in assets still held	0	0
Fair Value, Measurements, Nonrecurring [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-lived assets held and used	82.8
Long-lived assets held for sale	25.6
Total	108.4
Fair Value, Measurements, Nonrecurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-lived assets held and used	0
Long-lived assets held for sale	0
Total	0
Fair Value, Measurements, Nonrecurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-lived assets held and used	0
Long-lived assets held for sale	25.6
Total	25.6
Fair Value, Measurements, Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-lived assets held and used	82.8
Long-lived assets held for sale	0
Total	$ 82.8