Pension and Postretirement Benefit Costs (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2014 Pension Plans, Defined Benefit [Member]	Jun. 30, 2013 Pension Plans, Defined Benefit [Member]	Jun. 30, 2014 Pension Plans, Defined Benefit [Member]	Jun. 30, 2013 Pension Plans, Defined Benefit [Member]	Jun. 30, 2014 Other Postretirement Benefit Plan, Defined Benefit [Member]	Jun. 30, 2013 Other Postretirement Benefit Plan, Defined Benefit [Member]	Jun. 30, 2014 Other Postretirement Benefit Plan, Defined Benefit [Member]	Jun. 30, 2013 Other Postretirement Benefit Plan, Defined Benefit [Member]	Dec. 31, 2014 Scenario, Forecast [Member] Pension Plans, Defined Benefit [Member]	Dec. 31, 2014 Scenario, Forecast [Member] Other Postretirement Benefit Plan, Defined Benefit [Member]
Components of net periodic benefit cost
Service cost for benefits earned	$ 0.5	$ 0.5	$ 1.0	$ 1.1	$ 3.0	$ 3.9	$ 6.1	$ 7.8
Interest cost on projected or accumulated benefit obligation	11.3	10.5	22.7	21.1	9.1	10.4	18.2	20.9
Expected return on plan assets	(13.5)	(14.8)	(27.1)	(29.7)
Amortization of prior service cost and net actuarial loss	7.8	16.7	15.7	33.3	4.0	7.1	7.9	12.7
Net periodic benefit cost	6.1	12.9	12.3	25.8	16.1	21.4	32.2	41.4
Funding threshhold	80.00%		80.00%
Employer contributions to pension plan	1.6		2.4
Estimated contribution in 2014 to pension plan									13.0
Increase in accumulated postretirement benefit obligation, before tax							27.6
Defined benefit plans estimated additional incremental contributions in 2014										$ 2.0