Employee Benefits (Tables)

6 Months Ended

Jun. 30, 2013

Compensation and Retirement Disclosure [Abstract]

Pension and Other Postretirement Benefit Costs

	Pension
	Three Months Ended						Six Months Ended
	June 30,						June 30,
	2013			2012			2013			2012
	(in millions)
Service cost	$	0.9		$	0.9		$	1.9		$	1.9
Interest cost	1.3			1.2			2.5			2.4
Expected return on plan assets	(1.0		)	(0.9		)	(2.0		)	(1.8		)
Amortization of prior service costs	1.3			1.3			2.5			2.6
Amortization of actuarial loss	0.6			0.2			1.2			0.4
Periodic expense	$	3.1		$	2.7		$	6.1		$	5.5

	Postretirement Benefits
	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2013		2012		2013		2012
	(in millions)
Service cost	$	—	$	—	$	—	$	—
Interest cost	0.1		0.1		0.2		0.2
Amortization of prior service costs	0.1		0.1		0.2		0.2
Recognized net actuarial loss	—		—		—		—
Periodic expense	$	0.2	$	0.2	$	0.4	$	0.4