Employee Benefits (Tables)

3 Months Ended

Mar. 31, 2016

Compensation and Retirement Disclosure [Abstract]

Schedule of the components of net periodic benefit cost

The following tables show the components of net periodic pension and OPEB costs for our benefit plans:

	Pension Costs
	Three Months Ended March 31
(in millions)	2016			2015
Service cost	$	2.7		$	3.7
Interest cost	12.6			13.3
Expected return on plan assets	(19.4		)	(21.0		)
Amortization of prior service cost	0.4			0.5
Amortization of net actuarial loss	8.0			9.0
Net periodic benefit cost	$	4.3		$	5.5

	OPEB Costs
	Three Months Ended March 31
(in millions)	2016			2015
Service cost	$	0.1		$	2.4
Interest cost	1.9			3.4
Expected return on plan assets	(1.2		)	(4.0		)
Amortization of prior service credit	(0.3		)	(0.3		)
Amortization of net actuarial loss	0.2			0.3
Net periodic benefit cost	$	0.7		$	1.8