Pension and Other Postretirement Benefits (Tables)

6 Months Ended

Jun. 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
	June 30, 2015									June 30, 2014
	Pension			OPEB			Consolidated			Pension			OPEB			Consolidated
	(In millions)
Net periodic pension and OPEB cost:
Service cost - benefits earned during the year	$	2.6		$	0.4		$	3.0		$	3.3		$	0.8		$	4.1
Interest cost on projected benefit obligation	34.9			1.5			36.4			42.6			1.9			44.5
Expected return on plan assets	(44.6		)	—			(44.6		)	(49.8		)	—			(49.8		)
Amortization of prior service cost (benefit)	0.2			(0.1		)	0.1			0.2			(0.7		)	(0.5		)
Amortization of net actuarial loss (gain)	11.9			—			11.9			9.3			(0.3		)	9.0
Less: expected participant contributions	(0.2		)	—			(0.2		)	(0.3		)	—			(0.3		)
Net periodic pension and OPEB cost	$	4.8		$	1.8		$	6.6		$	5.3		$	1.7		$	7.0

	For the Six Months Ended
	June 30, 2015									June 30, 2014
	Pension			OPEB			Consolidated			Pension			OPEB			Consolidated
	(In millions)
Net periodic pension and OPEB cost:
Service cost - benefits earned during the year	$	5.2		$	0.9		$	6.1		$	6.6		$	1.5		$	8.1
Interest cost on projected benefit obligation	69.3			3.0			72.3			84.7			3.6			88.3
Expected return on plan assets	(88.7		)	—			(88.7		)	(98.9		)	—			(98.9		)
Amortization of prior service cost (benefit)	0.4			(0.2		)	0.2			0.4			(1.5		)	(1.1		)
Amortization of net actuarial loss (gain)	23.1			—			23.1			18.4			(0.5		)	17.9
Curtailment (gain) loss	(1.0		)	—			(1.0		)	—			—			—
Less: expected participant contributions	(0.4		)	—			(0.4		)	(0.6		)	—			(0.6		)
Net periodic pension and OPEB cost	$	7.9		$	3.7		$	11.6		$	10.6		$	3.1		$	13.7