Employee Benefit Plans (Fair Value of Plan Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets		$ 617.1
Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets		547.7
Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets		0.0
Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets		30.5
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	$ 711.0	$ 617.1	$ 691.8
Percentage of Fixed Income Securities Consisting of Foreign Securities	10.00%	17.00%
Percentage of fixed income securities consisting of investment-grade corporate bonds	43.00%	36.00%
Percentage of fixed income securities consisting of high-yield securities	14.00%	13.00%
Percentage of fixed income securities consisting of government treasuries	18.00%	27.00%
Percentage of fixed income securities consisting of other various fixed income securities	6.00%	7.00%
Percentage of alternative investments consisting of long-short equity funds	24.00%	22.00%
Percentage of alternative investments consisting of event-driven funds	21.00%	22.00%
Percentage of alternative investments consisting of relative value funds	42.00%	44.00%
Percentage of alternative investments consisting of credit funds	6.00%	5.00%
Percentage of alternative investments consisting of hedged and non-hedged funds	7.00%	7.00%
Pension Benefits | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	$ 564.9
Pension Benefits | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	66.9
Pension Benefits | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	33.1	$ 30.5	27.8
Pension Benefits | Equity Securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	261.7	226.9
Pension Benefits | Equity Securities | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	194.8	226.9
Pension Benefits | Equity Securities | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	66.9	0.0
Pension Benefits | Equity Securities | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Pension Benefits | Global Equities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	183.4	104.4
Pension Benefits | Global Equities | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	116.5	104.4
Pension Benefits | Global Equities | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	66.9	0.0
Pension Benefits | Global Equities | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Pension Benefits | Non-U.S. Equities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	3.8	3.0
Pension Benefits | Non-U.S. Equities | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	3.8	3.0
Pension Benefits | Non-U.S. Equities | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Pension Benefits | Non-U.S. Equities | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Pension Benefits | U.K. Equities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	65.2	112.4
Pension Benefits | U.K. Equities | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	65.2	112.4
Pension Benefits | U.K. Equities | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Pension Benefits | U.K. Equities | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Pension Benefits | U.S. Large Cap Equities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	5.9	4.5
Pension Benefits | U.S. Large Cap Equities | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	5.9	4.5
Pension Benefits | U.S. Large Cap Equities | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Pension Benefits | U.S. Large Cap Equities | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Pension Benefits | U.S. Small Cap Equities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	3.4	2.4
Pension Benefits | U.S. Small Cap Equities | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	3.4	2.4
Pension Benefits | U.S. Small Cap Equities | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Pension Benefits | U.S. Small Cap Equities | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Pension Benefits | Fixed Income Securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	370.1	320.8
Pension Benefits | Fixed Income Securities | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	370.1	320.8
Pension Benefits | Fixed Income Securities | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Pension Benefits | Fixed Income Securities | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Pension Benefits | Private Equity Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	2.3	2.3
Pension Benefits | Private Equity Funds [Member] | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Pension Benefits | Private Equity Funds [Member] | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Pension Benefits | Private Equity Funds [Member] | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	2.3	2.3
Pension Benefits | Aggregate Fixed Income
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	150.1	131.5
Pension Benefits | Aggregate Fixed Income | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	150.1	131.5
Pension Benefits | Aggregate Fixed Income | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Pension Benefits | Aggregate Fixed Income | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Pension Benefits | International Fixed Income
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	220.0	189.3
Pension Benefits | International Fixed Income | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	220.0	189.3
Pension Benefits | International Fixed Income | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Pension Benefits | International Fixed Income | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Pension Benefits | Cash and Cash Equivalents
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	33.3	31.8
Pension Benefits | Cash and Cash Equivalents | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Pension Benefits | Cash and Cash Equivalents | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Pension Benefits | Cash and Cash Equivalents | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Pension Benefits | Alternative Investments
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	35.6	34.1
Pension Benefits | Alternative Investments | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Pension Benefits | Alternative Investments | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Pension Benefits | Alternative Investments | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	2.3	2.3	2.4
Pension Benefits | Miscellaneous Funds
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	30.8	28.2
Pension Benefits | Miscellaneous Funds | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Pension Benefits | Miscellaneous Funds | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Pension Benefits | Miscellaneous Funds | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	30.8	28.2	$ 25.4
Pension Benefits | Cash and cash equivalents measured at net asset value [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	12.8	7.1
Pension Benefits | Cash [Member] | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Pension Benefits | Cash [Member] | Level 2
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Pension Benefits | Cash [Member] | Level 3
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	0.0	0.0
Preferred Stock [Member] | Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets		0.2
Preferred Stock [Member] | Pension Benefits | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets		0.2
UNITED STATES | Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Plan Assets	38.3	36.8
Defined Benefit Plan, Pension Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation	172.5	145.6
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Accumulated Benefit Obligation	$ 151.9	$ 128.7