Retirement Benefit Plans - Assets Measured at Fair Value (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension Plan, Defined Benefit [Member]
Assets:
Total Assets	$ 553.7	$ 1,772.4	$ 2,870.0
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	553.7	1,772.4
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	65.9	55.3
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member] | Government and agency securities [Member]
Assets:
Total Assets	35.1	505.9
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Total Assets	56.0	473.7
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member]
Assets:
Total Assets	9.8	22.7
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Securities [Member]
Assets:
Total Assets	6.1	16.3
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member] | Asset backed securities [Member]
Assets:
Total Assets		0.0
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - equities [Member]
Assets:
Total Assets	13.0	22.6
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Funds [Member]
Assets:
Total Assets	14.2	27.4
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - fixed income [Member]
Assets:
Total Assets	173.5	379.5
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - other [Member]
Assets:
Total Assets	0.0	0.0
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member] | Limited partnership [Member]
Assets:
Total Assets	52.8	66.1
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member] | Real Estate [Member]
Assets:
Total Assets	99.7	112.6
Pension Plan, Defined Benefit [Member] | Fair Value, Measurements, Recurring [Member] | Risk Parity [Member]
Assets:
Total Assets	27.6		90.3
Pension Plan, Defined Benefit [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	72.6	536.2
Pension Plan, Defined Benefit [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	23.9	0.8
Pension Plan, Defined Benefit [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Government and agency securities [Member]
Assets:
Total Assets	32.9	496.4
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	9.7	22.7
Pension Plan, Defined Benefit [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Securities [Member]
Assets:
Total Assets	6.1	16.3
Pension Plan, Defined Benefit [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Asset backed securities [Member]
Assets:
Total Assets		0.0
Pension Plan, Defined Benefit [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - equities [Member]
Assets:
Total Assets	0.0	0.0
Pension Plan, Defined Benefit [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Funds [Member]
Assets:
Total Assets	0.0	0.0
Pension Plan, Defined Benefit [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - fixed income [Member]
Assets:
Total Assets	0.0	0.0
Pension Plan, Defined Benefit [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - other [Member]
Assets:
Total Assets	0.0	0.0
Pension Plan, Defined Benefit [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Limited partnership [Member]
Assets:
Total Assets	0.0	0.0
Pension Plan, Defined Benefit [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Real Estate [Member]
Assets:
Total Assets	0.0	0.0
Pension Plan, Defined Benefit [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Risk Parity [Member]
Assets:
Total Assets	0.0		0.0
Pension Plan, Defined Benefit [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	400.5	1,142.3
Pension Plan, Defined Benefit [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	42.0	54.5
Pension Plan, Defined Benefit [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Government and agency securities [Member]
Assets:
Total Assets	2.2	9.5
Pension Plan, Defined Benefit [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Total Assets	56.0	473.7
Pension Plan, Defined Benefit [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member]
Assets:
Total Assets	0.1	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] | Asset backed securities [Member]
Assets:
Total Assets		0.0
Pension Plan, Defined Benefit [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - equities [Member]
Assets:
Total Assets	13.0	22.6
Pension Plan, Defined Benefit [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Funds [Member]
Assets:
Total Assets	14.2	27.4
Pension Plan, Defined Benefit [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - fixed income [Member]
Assets:
Total Assets	173.5	379.5
Pension Plan, Defined Benefit [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - other [Member]
Assets:
Total Assets	0.0	0.0
Pension Plan, Defined Benefit [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Limited partnership [Member]
Assets:
Total Assets	0.0	0.0
Pension Plan, Defined Benefit [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Real Estate [Member]
Assets:
Total Assets	71.9	84.8
Pension Plan, Defined Benefit [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Risk Parity [Member]
Assets:
Total Assets	27.6		90.3
Pension Plan, Defined Benefit [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	80.6	93.9
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] | Asset backed securities [Member]
Assets:
Total Assets		0.0
Pension Plan, Defined Benefit [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - equities [Member]
Assets:
Total Assets	0.0	0.0
Pension Plan, Defined Benefit [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Funds [Member]
Assets:
Total Assets	0.0	0.0
Pension Plan, Defined Benefit [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - fixed income [Member]
Assets:
Total Assets	0.0	0.0
Pension Plan, Defined Benefit [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - other [Member]
Assets:
Total Assets	0.0	0.0
Pension Plan, Defined Benefit [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Limited partnership [Member]
Assets:
Total Assets	52.8	66.1
Pension Plan, Defined Benefit [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Real Estate [Member]
Assets:
Total Assets	27.8	27.8
Pension Plan, Defined Benefit [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Risk Parity [Member]
Assets:
Total Assets	0.0		0.0
International Plans [Member]
Assets:
Total Assets	304.6	349.4	$ 420.6
International Plans [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	304.6	349.4
International Plans [Member] | Fair Value, Measurements, Recurring [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	31.0	25.5
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	3.0	2.7
International Plans [Member] | Fair Value, Measurements, Recurring [Member] | Equity securities [Member]
Assets:
Total Assets	0.0	30.2
International Plans [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Securities [Member]
Assets:
Total Assets	0.9	26.6
International Plans [Member] | Fair Value, Measurements, Recurring [Member] | Asset backed securities [Member]
Assets:
Total Assets		3.4
International Plans [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - equities [Member]
Assets:
Total Assets	0.0	2.1
International Plans [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Funds [Member]
Assets:
Total Assets	81.4	60.6
International Plans [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - fixed income [Member]
Assets:
Total Assets	85.0	108.9
International Plans [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - other [Member]
Assets:
Total Assets	103.3	89.4
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] | Risk Parity [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	12.8	55.9
International Plans [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	12.8	0.0
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	30.2
International Plans [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Securities [Member]
Assets:
Total Assets	0.0	25.7
International Plans [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Asset backed securities [Member]
Assets:
Total Assets		0.0
International Plans [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - equities [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Funds [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - fixed income [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - other [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Limited partnership [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Real Estate [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Risk Parity [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Total Assets	291.8	293.5
International Plans [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Cash and cash equivalents [Member]
Assets:
Total Assets	18.2	25.5
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	3.0	2.7
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	0.9	0.9
International Plans [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Asset backed securities [Member]
Assets:
Total Assets		3.4
International Plans [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - equities [Member]
Assets:
Total Assets	0.0	2.1
International Plans [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Funds [Member]
Assets:
Total Assets	81.4	60.6
International Plans [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - fixed income [Member]
Assets:
Total Assets	85.0	108.9
International Plans [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - other [Member]
Assets:
Total Assets	103.3	89.4
International Plans [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Limited partnership [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Real Estate [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Risk Parity [Member]
Assets:
Total Assets	0.0	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] | Asset backed securities [Member]
Assets:
Total Assets		0.0
International Plans [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - equities [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | International Equity Funds [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - fixed income [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Common collective funds - other [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Limited partnership [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Real Estate [Member]
Assets:
Total Assets	0.0	0.0
International Plans [Member] | Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Risk Parity [Member]
Assets:
Total Assets	$ 0.0	$ 0.0