Condensed Consolidated Statements of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Condensed Consolidated Statements of Comprehensive Income [Abstract]
Net income	$ 4.5	$ 13.5	$ 17.1	$ 31.4
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized (Gain) Loss Arising During Period, Net of Tax	0	1.4	0	1.4
Defined benefit pension and postretirement plans: [Abstract]
Amortization of prior service benefits included in net income, net of tax of ($1.1), ($1.2), ($2.3), ($2.4)	(2.1)	(2.0)	(4.2)	(4.0)
Amortization of net actuarial loss included in net income, net of tax of $2.8, $1.8, $4.8, $3.8	4.8	3.3	8.3	6.5
Reclassifiation Adjustment for Curtailments Included In Net Income, Net of Tax	0	2.7	0	2.7
Other comprehensive income	2.7	5.4	4.1	6.6
Total comprehensive income	$ 7.2	$ 18.9	$ 21.2	$ 38.0