Employee Benefits (Tables)

3 Months Ended

Mar. 31, 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						12 Months Ended
	March 31,						March 31,
	2014			2013			2014			2013
	(in millions)
Service cost	$	0.2		$	0.2		$	0.7		$	0.8
Interest cost	1.0			1.0			3.7			3.9
Expected return on plan assets	(0.8		)	(0.7		)	(2.7		)	(2.5		)
Amortization of transition obligation	—			—			—			1.2
Recognized net actuarial loss	0.3			0.7			2.6			2.6
Accretion of regulatory liability	0.2			0.2			0.5			0.3
Net postretirement benefit cost	$	0.9		$	1.4		$	4.8		$	6.3

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

	3 Months Ended						12 Months Ended
	March 31,						March 31,
	2014			2013			2014			2013
	(in millions)
Service cost	$	3.0		$	3.5		$	13.4		$	13.2
Interest cost	8.4			7.8			31.2			31.4
Expected return on plan assets	(10.6		)	(9.5		)	(39.2		)	(33.6		)
Prior service and other costs	0.1			0.3			0.9			1.1
Recognized net actuarial loss	3.9			6.8			26.0			26.3
Net pension cost	$	4.8		$	8.9		$	32.3		$	38.4