Pension and Other Postretirement Benefit Plans Activity in Level 3 (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Pension [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Actual Return on Plan Assets	$ 33.1	$ 45.6
Pension [Member] | Equity Securities (Auction Rate Securities) [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	6.7	9.1
Actual Return on Plan Assets	0	0
Purchases, Sales and Settlements, Net	(6.7)	(2.4)
Ending Balance	0	6.7
Pension [Member] | Private Equity Funds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	50.7	44.7
Actual Return on Plan Assets	30.9	(4.1)
Purchases, Sales and Settlements, Net	(12.6)	10.1
Ending Balance	69.0	50.7
Pension [Member] | Real Estate [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	20.1	17.3
Actual Return on Plan Assets	3.5	(6.1)
Purchases, Sales and Settlements, Net	(1.9)	8.9
Ending Balance	21.7	20.1
Postretirement Health and Life [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Actual Return on Plan Assets	0	12.0
Postretirement Health and Life [Member] | Private Equity Funds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	12.4	9.4
Actual Return on Plan Assets	1.1	1.4
Purchases, Sales and Settlements, Net	0.5	1.6
Ending Balance	$ 14.0	$ 12.4