Pension and Other Postretirement Benefits (Tables)

9 Months Ended

Sep. 30, 2015

Compensation and Retirement Disclosure [Abstract]

Net periodic pension and OPEB cost

14. Pension and Other Postretirement Benefits("OPEB")

	For the Three Months Ended
	September 30, 2015									September 30, 2014
	Pension			OPEB			Consolidated			Pension			OPEB			Consolidated
	(In millions)
Net periodic pension and OPEB cost:
Service cost - benefits earned during the year	$	2.1		$	0.7		$	2.8		$	3.4		$	0.8		$	4.2
Interest cost on projected benefit obligation	33.9			1.6			35.5			42.5			1.8			44.3
Expected return on plan assets	(44.0		)	—			(44.0		)	(50.6		)	—			(50.6		)
Amortization of prior service cost (benefit)	0.2			(0.4		)	(0.2		)	0.1			(0.8		)	(0.7		)
Amortization of net actuarial loss (gain)	12.1			—			12.1			9.2			(0.2		)	9.0
Less: expected participant contributions	(0.2		)	—			(0.2		)	(0.2		)	—			(0.2		)
Net periodic pension and OPEB cost	$	4.1		$	1.9		$	6.0		$	4.4		$	1.6		$	6.0

	For the Nine Months Ended
	September 30, 2015									September 30, 2014
	Pension			OPEB			Consolidated			Pension			OPEB			Consolidated
	(In millions)
Net periodic pension and OPEB cost:
Service cost - benefits earned during the year	$	7.3		$	1.6		$	8.9		$	10.0		$	2.3		$	12.3
Interest cost on projected benefit obligation	103.2			4.6			107.8			127.2			5.4			132.6
Expected return on plan assets	(132.7		)	—			(132.7		)	(149.5		)	—			(149.5		)
Amortization of prior service cost (benefit)	0.6			(0.6		)	—			0.5			(2.3		)	(1.8		)
Amortization of net actuarial loss (gain)	35.2			—			35.2			27.6			(0.7		)	26.9
Curtailment (gain) loss	(1.0		)	—			(1.0		)	—			—			—
Less: expected participant contributions	(0.6		)	—			(0.6		)	(0.8		)	—			(0.8		)
Net periodic pension and OPEB cost	$	12.0		$	5.6		$	17.6		$	15.0		$	4.7		$	19.7