Postretirement benefits (Tables) (Other Postretirement Benefit Plans, Defined Benefit [Member])

12 Months Ended

Dec. 31, 2014

Other Postretirement Benefit Plans, Defined Benefit [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Schedule of Net Funded Status [Table Text Block]

Changes in benefit obligation and plan assets, and a reconciliation of the funded status at December 31, 2014 and 2013, are as follows: 

(in millions)	2014			2013
Change in Benefit Obligation
Benefit obligation at the beginning of the year	$	7.9		$	9.1
Service cost	0.1			0.3
Interest cost	0.3			0.4
Participant contributions	0.7			0.6
Plan curtailment (gain)	(1.4		)	—
Actuarial loss (gain)	0.7			(1.5		)
Benefits paid	(1.2		)	(1.0		)
Benefit obligation at the end of the year	$	7.1		$	7.9
Change in Plan Assets
Fair value of plan assets at the beginning of the year	$	—		$	—
Participant contributions	0.7			0.6
Employer contribution	0.5			0.4
Benefits paid	(1.2		)	(1.0		)
Fair value of plan assets at the end of the year	$	—		$	—
Unfunded status at year end:	$	(7.1	)	$	(7.9	)

(in millions)	2014			2013
Amount recognized in consolidated balance sheet consists of:
Accrued benefit liability, current	$	(0.5	)	$	(0.6	)
Accrued benefit liability, non-current	(6.6		)	(7.3		)
Sub-total	(7.1		)	(7.9		)
Deferred tax liability	(1.7		)	(3.1		)
Accumulated other comprehensive income	(2.7		)	(4.8		)
Net amount related to postretirement benefit plans	$	(11.5	)	$	(15.8	)

Schedule of Net Periodic Benefit Cost Not yet Recognized [Table Text Block]

Accumulated other comprehensive income related to other postretirement benefit plans is as follows: 

(in millions)	2014			2013
Unrecognized net actuarial gains	$	(4.4	)	$	(5.5	)
Unrecognized net prior service credits	—			(2.4		)
Tax expense	1.7			3.1
Accumulated other comprehensive income, end of year	$	(2.7	)	$	(4.8	)