Employee Benefits (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Employee Benefit Plans
Pension Contributions			$ 100.0	$ 0.0
Pension Benefits
Components of net periodic benefit cost
Service cost	$ 11.3	$ 2.6	19.1	7.6
Interest cost	31.9	17.0	62.2	51.1
Expected return on plan assets	(52.1)	(24.7)	(103.5)	(74.0)
Amortization of prior service cost (credit)	0.7	0.6	1.7	1.6
Amortization of net actuarial loss	22.7	9.1	45.7	27.5
Net Periodic Benefit Cost	14.5	4.6	25.2	13.8
Other Postretirement Benefits
Components of net periodic benefit cost
Service cost	8.0	2.1	12.7	6.4
Interest cost	9.3	4.4	17.4	13.3
Expected return on plan assets	(13.9)	(5.9)	(25.7)	(17.8)
Amortization of prior service cost (credit)	(2.9)	(0.4)	(3.5)	(1.3)
Amortization of net actuarial loss	1.5	0.3	2.5	0.9
Net Periodic Benefit Cost	$ 2.0	$ 0.5	$ 3.4	$ 1.5