Employee Benefits (Tables)

6 Months Ended

Jun. 30, 2014

Compensation and Retirement Disclosure [Abstract]

Schedule of Defined Benefit Plans Disclosures

Net periodic postretirement benefit cost components are listed in the table below:

	3 Months Ended						6 Months Ended						12 Months Ended
	June 30,						June 30,						June 30,
	2014			2013			2014			2013			2014			2013
	(in millions)
Service cost	$	0.1		$	0.2		$	0.3		$	0.4		$	0.6		$	0.8
Interest cost	1.0			0.9			2.0			1.9			3.8			3.9
Expected return on plan assets	(0.7		)	(0.6		)	(1.5		)	(1.3		)	(2.8		)	(2.5		)
Amortization of transition obligation	—			—			—			—			—			0.8
Recognized net actuarial loss	0.3			0.7			0.6			1.4			2.2			2.8
Accretion of regulatory liability	0.2			0.1			0.4			0.3			0.6			0.2
Net postretirement benefit cost	$	0.9		$	1.3		$	1.8		$	2.7		$	4.4		$	6.0

Components of the qualified and nonqualified net periodic pension cost are listed in the table below:

	3 Months Ended						6 Months Ended						12 Months Ended
	June 30,						June 30,						June 30,
	2014			2013			2014			2013			2014			2013
	(in millions)
Service cost	$	3.0		$	3.6		$	6.0		$	7.1		$	12.8		$	13.5
Interest cost	8.3			7.7			16.7			15.5			31.8			31.4
Expected return on plan assets	(10.7		)	(9.6		)	(21.3		)	(19.1		)	(40.3		)	(35.2		)
Prior service and other costs	0.2			0.3			0.3			0.6			0.8			1.0
Recognized net actuarial loss	4.0			6.9			7.9			13.7			23.1			27.8
Net pension cost	$	4.8		$	8.9		$	9.6		$	17.8		$	28.2		$	38.5