Retirement and Other Postretirement Benefit Plans - Schedule of Pension Assets Measured at Fair Value (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Fair value measurements	$ 171.4	$ 160.4
Equity Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value measurements	53.8	51.9
Diversified Growth Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value measurements	41.2	44.2
Liability Driven Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value measurements	34.4	35.9
Index Linked Gilts
Defined Benefit Plan Disclosure [Line Items]
Fair value measurements	36.1	8.4
Other Insurance Product Line
Defined Benefit Plan Disclosure [Line Items]
Fair value measurements	3.6	3.5
Diversified Investment, Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value measurements	2.1	2.1
Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value measurements	0.2	0.4
Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value measurements		14.0
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value measurements	0.2	132.9
Level 1 | Equity Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value measurements		51.9
Level 1 | Diversified Growth Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value measurements		22.3
Level 1 | Liability Driven Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value measurements		35.9
Level 1 | Index Linked Gilts
Defined Benefit Plan Disclosure [Line Items]
Fair value measurements		8.4
Level 1 | Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value measurements	0.2	0.4
Level 1 | Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value measurements		14.0
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value measurements	165.5	21.9
Level 2 | Equity Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value measurements	53.8
Level 2 | Diversified Growth Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value measurements	41.2	21.9
Level 2 | Liability Driven Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value measurements	34.4
Level 2 | Index Linked Gilts
Defined Benefit Plan Disclosure [Line Items]
Fair value measurements	36.1
Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value measurements	5.7	5.6	$ 5.7
Actual return on plan assets	0.3	0.4
Purchases,sales and settlements		0.1
Changes due to exchange rates	(0.2)	(0.6)
Level 3 | Other Insurance Product Line
Defined Benefit Plan Disclosure [Line Items]
Fair value measurements	3.6	3.5	3.2
Actual return on plan assets	0.2	0.3
Purchases,sales and settlements		0.3
Changes due to exchange rates	(0.1)	(0.3)
Level 3 | Diversified Investment, Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value measurements	2.1	2.1	$ 2.5
Actual return on plan assets	0.1	0.1
Purchases,sales and settlements		(0.2)
Changes due to exchange rates	$ (0.1)	$ (0.3)