Employee Benefit Plans - Change in Benefit Obligation and Plan Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Amounts recognized in the balance sheet consist of:
Non-current liabilities	$ (2.4)	$ (7.5)
Pension Benefits
Change in Benefit Obligation:
Obligation at beginning of year	37.0	43.6
Interest cost	1.2	1.7	$ 1.8
Actuarial loss (gain)	1.7	(2.0)
Benefit payments	(2.4)	(2.8)
Group annuity contract discontinuance	0.0	(1.3)
Settlement of accumulated benefits	(2.7)	(2.2)
Benefit obligation at end of year	34.8	37.0	43.6
Change in Plan Assets:
Fair value of plan assets at beginning of year	32.3	40.4
Actual return on plan assets	1.4	(1.8)
Employer contributions	1.9	0.0
Benefit payments	(2.4)	(2.8)
Group annuity contract discontinuance	0.0	(1.3)
Settlement of accumulated benefits	(2.7)	(2.2)
Fair value of plan assets at end of year	30.5	32.3	40.4
Defined Benefit Plan, Funded Status of Plan [Abstract]
Funded status at end of year	(4.3)	(4.7)
Amounts recognized in the balance sheet consist of:
Current liabilities	(4.3)	0.0
Non-current liabilities	0.0	(4.7)
Total liabilities	(4.3)	(4.7)
Amounts recognized in AOCI consist of:
Net actuarial loss (gain)	17.7	17.5
Total	17.7	17.5
Accumulated benefit obligation	34.8	37.0
Settlement charge	1.3	1.6	0.0
Other Post-retirement Benefits
Change in Benefit Obligation:
Obligation at beginning of year	3.0	3.0
Interest cost	0.2	0.1	0.1
Actuarial loss (gain)	(0.5)	0.1
Benefit payments	(0.1)	(0.2)
Group annuity contract discontinuance	0.0	0.0
Settlement of accumulated benefits	0.0	0.0
Benefit obligation at end of year	2.6	3.0	3.0
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
Employer contributions	0.1	0.2
Benefit payments	(0.1)	(0.2)
Group annuity contract discontinuance	0.0	0.0
Settlement of accumulated benefits	0.0	0.0
Fair value of plan assets at end of year	0.0	0.0	0.0
Defined Benefit Plan, Funded Status of Plan [Abstract]
Funded status at end of year	(2.6)	(3.0)
Amounts recognized in the balance sheet consist of:
Current liabilities	(0.2)	(0.2)
Non-current liabilities	(2.4)	(2.8)
Total liabilities	(2.6)	(3.0)
Amounts recognized in AOCI consist of:
Net actuarial loss (gain)	(0.7)	(0.2)
Total	(0.7)	(0.2)
Settlement charge	$ 0.0	$ 0.0	$ 0.0