Retirement Benefit Plans - Assets Measured at Fair Value (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Plan, Defined Benefit [Member]
Assets:
Total Assets	$ 529.6	$ 553.7	$ 1,772.4
Pension Plan, Defined Benefit [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	0.0	41.8
Pension Plan, Defined Benefit [Member] | Corporate bonds [Member]
Assets:
Total Assets	0.0	0.0
Pension Plan, Defined Benefit [Member] | Equity securities [Member]
Assets:
Total Assets		0.1
Pension Plan, Defined Benefit [Member] | International Equity Securities [Member]
Assets:
Total Assets	0.0	0.0
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	529.6	553.7
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	34.3	23.9
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member] | Government and agency securities [Member]
Assets:
Total Assets	46.6	35.2
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Total Assets	65.7	56.0
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member]
Assets:
Total Assets	10.5	9.7
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Securities [Member]
Assets:
Total Assets	6.2	6.1
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member] | Common Collective funds - domestic equities [Member]
Assets:
Total Assets	14.0	13.0
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - international equities [Member]
Assets:
Total Assets	14.1	14.2
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - fixed income [Member]
Assets:
Total Assets	217.1	173.6
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member] | Limited partnership [Member]
Assets:
Total Assets	39.6	52.8
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member] | Real Estate [Member]
Assets:
Total Assets	22.1	99.7
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Fund [Member]
Assets:
Total Assets	41.5
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member] | Risk Parity [Member]
Assets:
Total Assets	17.9	27.6
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member] | Other Assets [Member]
Assets:
Total Assets	0.0	0.0
Pension Plan, Defined Benefit [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	136.5	72.7
Pension Plan, Defined Benefit [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	34.3	23.9
Pension Plan, Defined Benefit [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Government and agency securities [Member]
Assets:
Total Assets	44.0	33.0
Pension Plan, Defined Benefit [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Total Assets	0.0	0.0
Pension Plan, Defined Benefit [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member]
Assets:
Total Assets	10.5	9.7
Pension Plan, Defined Benefit [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Securities [Member]
Assets:
Total Assets	6.2	6.1
Pension Plan, Defined Benefit [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Fund [Member]
Assets:
Total Assets	41.5
Pension Plan, Defined Benefit [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	68.3	58.2
Pension Plan, Defined Benefit [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	0.0	0.0
Pension Plan, Defined Benefit [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Government and agency securities [Member]
Assets:
Total Assets	2.6	2.2
Pension Plan, Defined Benefit [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Total Assets	65.7	56.0
Pension Plan, Defined Benefit [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member]
Assets:
Total Assets	0.0	0.0
Pension Plan, Defined Benefit [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Securities [Member]
Assets:
Total Assets	0.0	0.0
Pension Plan, Defined Benefit [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Fund [Member]
Assets:
Total Assets	0.0
Pension Plan, Defined Benefit [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	0.0	0.0
Pension Plan, Defined Benefit [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	0.0	0.0
Pension Plan, Defined Benefit [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Government and agency securities [Member]
Assets:
Total Assets	0.0	0.0
Pension Plan, Defined Benefit [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Total Assets	0.0	0.0
Pension Plan, Defined Benefit [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member]
Assets:
Total Assets	0.0	0.0
Pension Plan, Defined Benefit [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Securities [Member]
Assets:
Total Assets	0.0	0.0
Pension Plan, Defined Benefit [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Fund [Member]
Assets:
Total Assets	0.0
International Plans [Member]
Assets:
Total Assets	268.7	304.6	$ 349.4
International Plans [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	3.4	18.2
International Plans [Member] | Corporate bonds [Member]
Assets:
Total Assets	2.7	3.0
International Plans [Member] | Equity securities [Member]
Assets:
Total Assets		0.0
International Plans [Member] | International Equity Securities [Member]
Assets:
Total Assets	1.5	0.9
International Plans [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	268.7	304.6
International Plans [Member] | Fair Value, Measurements, Recurring [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	0.8	12.8
International Plans [Member] | Fair Value, Measurements, Recurring [Member] | Government and agency securities [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Securities [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Fair Value, Measurements, Recurring [Member] | Common Collective funds - domestic equities [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - international equities [Member]
Assets:
Total Assets	33.4	81.4
International Plans [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - fixed income [Member]
Assets:
Total Assets	74.6	85.0
International Plans [Member] | Fair Value, Measurements, Recurring [Member] | Limited partnership [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Fair Value, Measurements, Recurring [Member] | Real Estate [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Fund [Member]
Assets:
Total Assets	0.0
International Plans [Member] | Fair Value, Measurements, Recurring [Member] | Risk Parity [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Fair Value, Measurements, Recurring [Member] | Other Assets [Member]
Assets:
Total Assets	152.3	103.3
International Plans [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	0.8	12.8
International Plans [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	0.8	12.8
International Plans [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Government and agency securities [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Securities [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Fund [Member]
Assets:
Total Assets	0.0
International Plans [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Government and agency securities [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Securities [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Fund [Member]
Assets:
Total Assets	0.0
International Plans [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Government and agency securities [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Securities [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual Fund [Member]
Assets:
Total Assets	0.0
Assets [Member] | Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	204.8	130.9
Assets [Member] | International Plans [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	$ 0.8	$ 12.8