Pensions and Postretirement Benefits (Summary of Change in Defined Benefit and Postretirement Benefit Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Change in plan assets
Fair value of plan assets at beginning of year	$ 125.7
Fair value of plan assets at end of year	117.3	$ 125.7
Funded (underfunded) status of the plans
Current liabilities	1.4	1.6
Pension Benefits
Change in benefit obligation
Benefit obligation at beginning of year	61.1	52.1
Service costs	2.6	2.2	$ 2.6
Interest costs	2.3	2.2	2.0
Actuarial (gains) losses	(3.0)	8.8
Plan amendment	0.0	0.4
Benefits and expenses paid, net of contributions	(4.6)	(4.6)
Benefit obligation at end of year	58.4	61.1	52.1
Change in plan assets
Fair value of plan assets at beginning of year	125.7	125.4
Actual return on plan assets	(2.9)	5.8
Company contributions	0.0	0.0
Cash transfer to fund postretirement benefit payments	(0.9)	(0.9)
Benefits and expenses paid, net of contributions	(4.6)	(4.6)
Fair value of plan assets at end of year	117.3	125.7	125.4
Funded (underfunded) status of the plans	58.9	64.6
Funded (underfunded) status of the plans
Noncurrent assets	58.9	64.6
Noncurrent liabilities	0.0	0.0
Current liabilities	0.0	0.0
Total assets (liabilities) recognized in the consolidated balance sheets	58.9	64.6
Amounts recognized in accumulated other comprehensive loss
Net actuarial loss	25.2	15.3
Net prior service cost (credit)	0.3	0.4
Accumulated other comprehensive loss	25.5	15.7
Postretirement Benefits
Change in benefit obligation
Benefit obligation at beginning of year	17.0	16.2
Service costs	0.0	0.0	0.1
Interest costs	0.6	0.6	0.6
Actuarial (gains) losses	(2.7)	1.9
Plan amendment	0.0	0.0
Benefits and expenses paid, net of contributions	(1.3)	(1.7)
Benefit obligation at end of year	13.5	17.0	16.2
Change in plan assets
Fair value of plan assets at beginning of year	0.0	0.0
Actual return on plan assets	0.0	0.0
Company contributions	1.3	1.7
Cash transfer to fund postretirement benefit payments	0.0	0.0
Benefits and expenses paid, net of contributions	(1.3)	(1.7)
Fair value of plan assets at end of year	0.0	0.0	$ 0.0
Funded (underfunded) status of the plans	(13.5)	(17.0)
Funded (underfunded) status of the plans
Noncurrent assets	0.0	0.0
Noncurrent liabilities	12.1	15.4
Current liabilities	1.4	1.6
Total assets (liabilities) recognized in the consolidated balance sheets	(13.5)	(17.0)
Amounts recognized in accumulated other comprehensive loss
Net actuarial loss	4.4	7.6
Net prior service cost (credit)	(0.3)	(0.4)
Accumulated other comprehensive loss	$ 4.1	$ 7.2