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Postretirement and Other Benefits - Fair Value of Plan Assets (Details) - Pension Plan [Member] - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016
UNITED STATES |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | $ 118.9 | $ 116.7
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 118.9 | 116.7
Fair value of plan assets at end of year | 128.7 | 118.9
UNITED STATES | Cash and Cash Equivalents [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 1.2 | 1.2
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 1.2 |
Fair value of plan assets at end of year | 1.1 | 1.2
UNITED STATES | Domestic Large Cap [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 8.3 | 8.3
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 8.3 |
Fair value of plan assets at end of year | 9.0 | 8.3
UNITED STATES | Domestic Small Cap [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 5.7 | 5.7
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 5.7 |
Fair value of plan assets at end of year | 5.8 | 5.7
UNITED STATES | International [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 23.7 | 23.7
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 23.7 |
Fair value of plan assets at end of year | 25.3 | 23.7
UNITED STATES | Fixed Income Securities [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 79.9 | 79.9
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 79.9 |
Fair value of plan assets at end of year | 87.4 | 79.9
UNITED STATES | Alternative Investment [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 0.1 | 0.1
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 0.1 |
Fair value of plan assets at end of year | 0.1 | 0.1
UNITED STATES | Level 1 [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 1.2 | 1.2
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 1.2 |
Fair value of plan assets at end of year | 1.1 | 1.2
UNITED STATES | Level 1 [Member] | Cash and Cash Equivalents [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 1.2 | 1.2
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 1.2 |
Fair value of plan assets at end of year | 1.1 | 1.2
UNITED STATES | Level 1 [Member] | Alternative Investment [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 0.0 | 0.0
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 0.0 |
Fair value of plan assets at end of year | 0.0 | 0.0
UNITED STATES | Level 2 [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 0.0 | 0.0
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 0.0 |
Fair value of plan assets at end of year | 56.3 | 0.0
UNITED STATES | Level 2 [Member] | Cash and Cash Equivalents [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 0.0 | 0.0
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 0.0 |
Fair value of plan assets at end of year | 0.0 | 0.0
UNITED STATES | Level 2 [Member] | Fixed Income Securities [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 56.3 |
Change in Plan Assets: |  |
Fair value of plan assets at end of year | 56.3 |
UNITED STATES | Level 2 [Member] | Alternative Investment [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 0.0 | 0.0
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 0.0 |
Fair value of plan assets at end of year | 0.0 | 0.0
UNITED STATES | Level 3 [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 0.1 | 0.3
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 0.1 | 0.3
Realized and unrealized gains | 0.0 | 0.0
Purchases | 0.0 | 0.0
Sales | 0.0 | (0.2)
Fair value of plan assets at end of year | 0.1 | 0.1
UNITED STATES | Level 3 [Member] | Cash and Cash Equivalents [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 0.0 | 0.0
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 0.0 |
Fair value of plan assets at end of year | 0.0 | 0.0
UNITED STATES | Level 3 [Member] | Alternative Investment [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 0.1 | 0.1
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 0.1 |
Fair value of plan assets at end of year | 0.1 | 0.1
FRANCE |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 6.1 | 8.4
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 6.1 | 8.4
Fair value of plan assets at end of year | 3.2 | 6.1
FRANCE | Cash and Cash Equivalents [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 1.5 | 1.5
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 1.5 |
Fair value of plan assets at end of year | 1.2 | 1.5
FRANCE | Domestic Large Cap [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 1.2 | 1.2
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 1.2 |
Fair value of plan assets at end of year | 1.0 | 1.2
FRANCE | Domestic Small Cap [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 0.0 | 0.0
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 0.0 |
Fair value of plan assets at end of year | 0.0 | 0.0
FRANCE | International [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 0.0 | 0.0
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 0.0 |
Fair value of plan assets at end of year | 0.0 | 0.0
FRANCE | Fixed Income Securities [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 3.2 | 3.2
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 3.2 |
Fair value of plan assets at end of year | 0.9 | 3.2
FRANCE | Alternative Investment [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 0.2 | 0.2
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 0.2 |
Fair value of plan assets at end of year | 0.1 | 0.2
FRANCE | Level 1 [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 2.7 | 2.7
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 2.7 |
Fair value of plan assets at end of year | 2.2 | 2.7
FRANCE | Level 1 [Member] | Cash and Cash Equivalents [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 1.5 | 1.5
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 1.5 |
Fair value of plan assets at end of year | 1.2 | 1.5
FRANCE | Level 1 [Member] | Domestic Large Cap [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 1.2 | 1.2
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 1.2 |
Fair value of plan assets at end of year | 1.0 | 1.2
FRANCE | Level 1 [Member] | Domestic Small Cap [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 0.0 | 0.0
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 0.0 |
Fair value of plan assets at end of year | 0.0 | 0.0
FRANCE | Level 1 [Member] | International [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 0.0 | 0.0
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 0.0 |
Fair value of plan assets at end of year | 0.0 | 0.0
FRANCE | Level 1 [Member] | Fixed Income Securities [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 0.0 | 0.0
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 0.0 |
Fair value of plan assets at end of year | 0.0 | 0.0
FRANCE | Level 1 [Member] | Alternative Investment [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 0.0 | 0.0
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 0.0 |
Fair value of plan assets at end of year | 0.0 | 0.0
FRANCE | Level 2 [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 3.4 | 3.4
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 3.4 |
Fair value of plan assets at end of year | 1.0 | 3.4
FRANCE | Level 2 [Member] | Cash and Cash Equivalents [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 0.0 | 0.0
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 0.0 |
Fair value of plan assets at end of year | 0.0 | 0.0
FRANCE | Level 2 [Member] | Domestic Large Cap [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 0.0 | 0.0
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 0.0 |
Fair value of plan assets at end of year | 0.0 | 0.0
FRANCE | Level 2 [Member] | Domestic Small Cap [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 0.0 | 0.0
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 0.0 |
Fair value of plan assets at end of year | 0.0 | 0.0
FRANCE | Level 2 [Member] | International [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 0.0 | 0.0
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 0.0 |
Fair value of plan assets at end of year | 0.0 | 0.0
FRANCE | Level 2 [Member] | Fixed Income Securities [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 3.2 | 3.2
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 3.2 |
Fair value of plan assets at end of year | 0.9 | 3.2
FRANCE | Level 2 [Member] | Alternative Investment [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 0.2 | 0.2
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 0.2 |
Fair value of plan assets at end of year | 0.1 | 0.2
Net Asset Value [Member] | UNITED STATES |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 117.6 | 117.6
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 117.6 |
Fair value of plan assets at end of year | 71.2 | 117.6
Net Asset Value [Member] | UNITED STATES | Domestic Large Cap [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 8.3 | 8.3
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 8.3 |
Fair value of plan assets at end of year | 9.0 | 8.3
Net Asset Value [Member] | UNITED STATES | Domestic Small Cap [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 5.7 | 5.7
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 5.7 |
Fair value of plan assets at end of year | 5.8 | 5.7
Net Asset Value [Member] | UNITED STATES | International [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 23.7 | 23.7
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 23.7 |
Fair value of plan assets at end of year | 25.3 | 23.7
Net Asset Value [Member] | UNITED STATES | Fixed Income Securities [Member] |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Fair value of plan assets | 79.9 | 79.9
Change in Plan Assets: |  |
Fair value of plan assets at beginning of year | 79.9 |
Fair value of plan assets at end of year | $ 31.1 | $ 79.9

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