Postretirement and Other Benefits - Funded Status (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
UNITED STATES \| Pension Plan [Member]
Change in Projected Benefit Obligation, or PBO:
PBO at beginning of year	$ 123.2	$ 123.4
Service cost	0.0	0.0	$ 0.0
Interest cost	4.8	5.2	5.0
Actuarial (gain) loss	3.9	2.4
Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant	0.0	0.0
Gross benefits paid	(7.8)	(7.8)
Currency translation effect	0.0	0.0
PBO at end of year	124.1	123.2	123.4
Change in Plan Assets:
Fair value of plan assets at beginning of year	118.9	116.7
Actual return on plan assets	17.6	10.0
Employer contributions	0.0	0.0
Participant contributions	0.0	0.0
Gross benefits paid	(7.8)	(7.8)
Currency translation effect	0.0	0.0
Fair value of plan assets at end of year	128.7	118.9	116.7
Funded status at end of year	4.6	(4.3)
UNITED STATES \| Other Postretirement Benefits Plan [Member]
Change in Projected Benefit Obligation, or PBO:
PBO at beginning of year	1.4	1.7
Service cost	0.0	0.0	0.0
Interest cost	0.1	0.1	0.1
Actuarial (gain) loss	0.2	0.0
Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant	0.1	0.1
Gross benefits paid	(0.4)	(0.5)
Currency translation effect	0.0	0.0
PBO at end of year	1.4	1.4	1.7
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	0.3	0.4
Participant contributions	0.1	0.1
Gross benefits paid	(0.4)	(0.5)
Currency translation effect	0.0	0.0
Fair value of plan assets at end of year	0.0	0.0	0.0
Funded status at end of year	(1.4)	(1.4)
FRANCE \| Pension Plan [Member]
Change in Projected Benefit Obligation, or PBO:
PBO at beginning of year	32.4	32.2
Service cost	1.1	1.0	1.3
Interest cost	0.4	0.4	0.4
Actuarial (gain) loss	(2.6)	2.1
Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant	0.0	0.0
Gross benefits paid	(5.7)	(3.0)
Currency translation effect	4.9	(0.3)
PBO at end of year	30.5	32.4	32.2
Change in Plan Assets:
Fair value of plan assets at beginning of year	6.1	8.4
Actual return on plan assets	0.2	0.1
Employer contributions	1.9	0.7
Participant contributions	0.0	0.0
Gross benefits paid	(5.6)	(2.9)
Currency translation effect	0.6	(0.2)
Fair value of plan assets at end of year	3.2	6.1	$ 8.4
Funded status at end of year	$ (27.3)	$ (26.3)

Defined Benefit Plan, Benefits Paid, Plan Assets

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Amount of increase (decrease) in plan assets of defined benefit plan from actual return (loss) determined by change in fair value of plan assets adjusted for contributions, benefit payments, and other expenses.

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Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan.

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Amount of payment to participant of defined benefit plan which decreases benefit obligation. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Amount of contributions received by defined benefit plan from participant which increase benefit obligation.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of contribution received by defined benefit plan from employer which increases plan assets.

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Fair value of assets that have been segregated and restricted to provide pension or postretirement benefits. Assets include, but are not limited to, stocks, bonds, other investments, earnings from investments, and contributions by the employer and employees.

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Amount of foreign currency translation gain (loss) which (increases) decreases benefit obligation of defined benefit plan.

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Amount of funded (unfunded) status of defined benefit plan, measured as difference between fair value of plan assets and benefit obligation. Includes, but is not limited to, overfunded (underfunded) status.

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Amount of cost recognized for passage of time related to defined benefit plan.

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Amount of contributions received by defined benefit plan from participant which increases plan assets.

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Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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