Fair Value Measurements Level 3 (Details) (Derivative Financial Instruments, Assets [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Derivative Financial Instruments, Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	$ 1.9	$ 2.2	$ 2.3	$ 3.1
Total realized/unrealized gains or (losses) included in non-operating income	1.0	3.7	5.3	4.8
Settlements	(1.3)	(3.5)	(6.0)	(5.5)
Balance at end of period	1.6	2.4	1.6	2.4
Total unrealized gains and (losses) included in non-operating income relating to assets and liabilities still on the consolidated balance sheet at period end	$ (0.3)	$ 0.3	$ (0.4)	$ (0.4)