Retirement Benefit Plans - Assets Measured at Fair Value (Details) - Pension Plan [Member] - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Foreign Plan [Member]
Assets:
Total Assets	$ 292.4	$ 268.7	$ 304.6
Foreign Plan [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	292.4	268.7
Foreign Plan [Member] | Fair Value, Measurements, Recurring [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	4.8	0.8
Foreign Plan [Member] | Fair Value, Measurements, Recurring [Member] | Government and agency securities [Member]
Assets:
Total Assets	0.0	0.0
Foreign Plan [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Total Assets	0.0	0.0
Foreign Plan [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member]
Assets:
Total Assets		0.0
Foreign Plan [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Securities [Member]
Assets:
Total Assets		0.0
Foreign Plan [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Securities [Member]
Assets:
Total Assets	1.0	1.5
Foreign Plan [Member] | Fair Value, Measurements, Recurring [Member] | Common Collective funds - domestic equities [Member]
Assets:
Total Assets	0.0	0.0
Foreign Plan [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - international equities [Member]
Assets:
Total Assets	25.3	33.4
Foreign Plan [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Funds [Member]
Assets:
Total Assets	86.2	74.6
Foreign Plan [Member] | Fair Value, Measurements, Recurring [Member] | Limited Partnership [Member]
Assets:
Total Assets	0.0	0.0
Foreign Plan [Member] | Fair Value, Measurements, Recurring [Member] | Real Estate [Member]
Assets:
Total Assets	0.0	0.0
Foreign Plan [Member] | Fair Value, Measurements, Recurring [Member] | Other Assets [Member]
Assets:
Total Assets	169.7	152.3
Foreign Plan [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Fund [Member]
Assets:
Total Assets	0.0	0.0
Foreign Plan [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Fund [Member]
Assets:
Total Assets	0.0
Foreign Plan [Member] | Fair Value, Measurements, Recurring [Member] | Cash and Cash Equivalents at Net Asset Value [Member]
Assets:
Total Assets	0.1	3.4
Foreign Plan [Member] | Fair Value, Measurements, Recurring [Member] | Corporate Bonds at Net Asset Value [Member]
Assets:
Total Assets	5.3	2.7
Foreign Plan [Member] | Fair Value, Measurements, Recurring [Member] | Risk Parity [Member]
Assets:
Total Assets		0.0
Foreign Plan [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	4.8	0.8
Foreign Plan [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	4.8	0.8
Foreign Plan [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Government and agency securities [Member]
Assets:
Total Assets	0.0	0.0
Foreign Plan [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Total Assets	0.0	0.0
Foreign Plan [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member]
Assets:
Total Assets		0.0
Foreign Plan [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Securities [Member]
Assets:
Total Assets		0.0
Foreign Plan [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Fund [Member]
Assets:
Total Assets	0.0	0.0
Foreign Plan [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Fund [Member]
Assets:
Total Assets	0.0
Foreign Plan [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	0.0	0.0
Foreign Plan [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	0.0	0.0
Foreign Plan [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Government and agency securities [Member]
Assets:
Total Assets	0.0	0.0
Foreign Plan [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Total Assets	0.0	0.0
Foreign Plan [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member]
Assets:
Total Assets		0.0
Foreign Plan [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Securities [Member]
Assets:
Total Assets		0.0
Foreign Plan [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Fund [Member]
Assets:
Total Assets	0.0	0.0
Foreign Plan [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Fund [Member]
Assets:
Total Assets	0.0
Foreign Plan [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	0.0	0.0
Foreign Plan [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	0.0	0.0
Foreign Plan [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Government and agency securities [Member]
Assets:
Total Assets	0.0	0.0
Foreign Plan [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Total Assets	0.0	0.0
Foreign Plan [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member]
Assets:
Total Assets		0.0
Foreign Plan [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Securities [Member]
Assets:
Total Assets		0.0
Foreign Plan [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Fund [Member]
Assets:
Total Assets	0.0	0.0
Foreign Plan [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Fund [Member]
Assets:
Total Assets	0.0
Foreign Plan [Member] | Assets [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	4.8	0.8
Domestic Plan [Member]
Assets:
Total Assets	531.9	529.6	$ 553.7
Domestic Plan [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	531.9	529.6
Domestic Plan [Member] | Fair Value, Measurements, Recurring [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	27.2	34.3
Domestic Plan [Member] | Fair Value, Measurements, Recurring [Member] | Government and agency securities [Member]
Assets:
Total Assets	18.9	46.6
Domestic Plan [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Total Assets	105.1	65.7
Domestic Plan [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member]
Assets:
Total Assets		10.5
Domestic Plan [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Securities [Member]
Assets:
Total Assets		6.2
Domestic Plan [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Securities [Member]
Assets:
Total Assets	0.0	0.0
Domestic Plan [Member] | Fair Value, Measurements, Recurring [Member] | Common Collective funds - domestic equities [Member]
Assets:
Total Assets	37.0	14.0
Domestic Plan [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - international equities [Member]
Assets:
Total Assets	11.5	14.1
Domestic Plan [Member] | Fair Value, Measurements, Recurring [Member] | Fixed Income Funds [Member]
Assets:
Total Assets	220.9	217.1
Domestic Plan [Member] | Fair Value, Measurements, Recurring [Member] | Limited Partnership [Member]
Assets:
Total Assets	31.8	39.6
Domestic Plan [Member] | Fair Value, Measurements, Recurring [Member] | Real Estate [Member]
Assets:
Total Assets	16.9	22.1
Domestic Plan [Member] | Fair Value, Measurements, Recurring [Member] | Other Assets [Member]
Assets:
Total Assets	0.0	0.0
Domestic Plan [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Fund [Member]
Assets:
Total Assets	44.9	41.5
Domestic Plan [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Fund [Member]
Assets:
Total Assets	17.5
Domestic Plan [Member] | Fair Value, Measurements, Recurring [Member] | Cash and Cash Equivalents at Net Asset Value [Member]
Assets:
Total Assets	0.2	0.0
Domestic Plan [Member] | Fair Value, Measurements, Recurring [Member] | Corporate Bonds at Net Asset Value [Member]
Assets:
Total Assets	0.0	0.0
Domestic Plan [Member] | Fair Value, Measurements, Recurring [Member] | Risk Parity [Member]
Assets:
Total Assets		17.9
Domestic Plan [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	105.1	136.5
Domestic Plan [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	27.2	34.3
Domestic Plan [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Government and agency securities [Member]
Assets:
Total Assets	15.5	44.0
Domestic Plan [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Total Assets	0.0	0.0
Domestic Plan [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member]
Assets:
Total Assets		10.5
Domestic Plan [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Securities [Member]
Assets:
Total Assets		6.2
Domestic Plan [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Fund [Member]
Assets:
Total Assets	44.9	41.5
Domestic Plan [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Fund [Member]
Assets:
Total Assets	17.5
Domestic Plan [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	108.5	68.3
Domestic Plan [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	0.0	0.0
Domestic Plan [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Government and agency securities [Member]
Assets:
Total Assets	3.4	2.6
Domestic Plan [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Total Assets	105.1	65.7
Domestic Plan [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member]
Assets:
Total Assets		0.0
Domestic Plan [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Securities [Member]
Assets:
Total Assets		0.0
Domestic Plan [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Fund [Member]
Assets:
Total Assets	0.0	0.0
Domestic Plan [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Fund [Member]
Assets:
Total Assets	0.0
Domestic Plan [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	0.0	0.0
Domestic Plan [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	0.0	0.0
Domestic Plan [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Government and agency securities [Member]
Assets:
Total Assets	0.0	0.0
Domestic Plan [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Total Assets	0.0	0.0
Domestic Plan [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member]
Assets:
Total Assets		0.0
Domestic Plan [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Securities [Member]
Assets:
Total Assets		0.0
Domestic Plan [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Fund [Member]
Assets:
Total Assets	0.0	0.0
Domestic Plan [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Fund [Member]
Assets:
Total Assets	0.0
Domestic Plan [Member] | Assets [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	$ 213.6	$ 204.8