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