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

12 Months Ended

Dec. 31, 2015

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, 2015 and 2014, are as follows: 

(in millions)	2015			2014
Change in Benefit Obligation
Benefit obligation at the beginning of the year	$	7.1		$	7.9
Service cost	—			0.1
Interest cost	0.3			0.3
Participant contributions	0.8			0.7
Plan curtailment gain	—			(1.4		)
Actuarial (gain) loss	(1.0		)	0.7
Benefits paid	(1.5		)	(1.2		)
Benefit obligation at the end of the year	$	5.7		$	7.1
Change in Plan Assets
Fair value of plan assets at the beginning of the year	$	—		$	—
Participant contributions	0.8			0.7
Employer contributions	0.7			0.5
Benefits paid	(1.5		)	(1.2		)
Fair value of plan assets at the end of the year	$	—		$	—
Unfunded status at year end:	$	(5.7	)	$	(7.1	)

(in millions)	2015			2014
Amount recognized in consolidated balance sheet consists of:
Accrued benefit liability, current	$	(0.4	)	$	(0.5	)
Accrued benefit liability, non-current	(5.3		)	(6.6		)
Sub-total	(5.7		)	(7.1		)
Deferred tax liability	(2.0		)	(1.7		)
Accumulated other comprehensive income	(3.1		)	(2.7		)
Net amount related to postretirement benefit plans	$	(10.8	)	$	(11.5	)

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)	2015			2014
Unrecognized net actuarial gains	$	(5.1	)	$	(4.4	)
Tax expense	2.0			1.7
Accumulated other comprehensive income, end of year	$	(3.1	)	$	(2.7	)