Pensions and Postretirement Benefits Other Than Pensions (Schedule of Fair Values of Company's Pension Plan Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Defined benefit plan, fair value of pension plan assets	$ 3,136.8	$ 2,766.9
Receivables and payables, net	9.2	12.1
Fair Value, Inputs, Level 1 [Member]
Defined benefit plan, fair value of pension plan assets	7.0	4.0
Fair Value, Inputs, Level 2 [Member]
Defined benefit plan, fair value of pension plan assets	2,019.1	1,795.7
Fair Value, Inputs, Level 3 [Member]
Defined benefit plan, fair value of pension plan assets	143.9	130.5
Net Assets, Segment [Member]
Defined benefit plan, fair value of pension plan assets	957.6	824.6
Derivative [Member]
Defined benefit plan, fair value of pension plan assets	0.4	(0.4)
Derivative [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Derivative [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan, fair value of pension plan assets	0.4	(0.4)
Derivative [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Derivative [Member] | Net Assets, Segment [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Real Estate Funds [Member]
Defined benefit plan, fair value of pension plan assets	3.4	4.1
Real Estate Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Real Estate Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Real Estate Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan, fair value of pension plan assets	3.4	4.1
Real Estate Funds [Member] | Net Assets, Segment [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Other Defined Benefit [Member]
Defined benefit plan, fair value of pension plan assets	114.1	101.6
Other Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Other Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Other Defined Benefit [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan, fair value of pension plan assets	114.1	101.6
Other Defined Benefit [Member] | Net Assets, Segment [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Cash and Cash Equivalents [Member]
Defined benefit plan, fair value of pension plan assets	33.3	30.8
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan, fair value of pension plan assets	7.0	4.0
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan, fair value of pension plan assets	26.3	26.8
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Cash and Cash Equivalents [Member] | Net Assets, Segment [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Registered mutual funds, equity specialty [Member]
Defined benefit plan, fair value of pension plan assets	61.5	51.1
Registered mutual funds, equity specialty [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Registered mutual funds, equity specialty [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Registered mutual funds, equity specialty [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Registered mutual funds, equity specialty [Member] | Net Assets, Segment [Member]
Defined benefit plan, fair value of pension plan assets	61.5	51.1
Equity Securities [Member]
Defined benefit plan, fair value of pension plan assets	726.7	571.8
Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Equity Securities [Member] | Net Assets, Segment [Member]
Defined benefit plan, fair value of pension plan assets	726.7	571.8
Commingled funds, equity specialty [Member]
Defined benefit plan, fair value of pension plan assets	665.2	520.7
Commingled funds, equity specialty [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Commingled funds, equity specialty [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Commingled funds, equity specialty [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Commingled funds, equity specialty [Member] | Net Assets, Segment [Member]
Defined benefit plan, fair value of pension plan assets	665.2	520.7
Fixed Income Investments [Member]
Defined benefit plan, fair value of pension plan assets	2,249.7	2,046.9
Fixed Income Investments [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Fixed Income Investments [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan, fair value of pension plan assets	1,992.4	1,769.3
Fixed Income Investments [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan, fair value of pension plan assets	26.4	24.8
Fixed Income Investments [Member] | Net Assets, Segment [Member]
Defined benefit plan, fair value of pension plan assets	230.9	252.8
Fixed Income Investments [Member] | Registered mutual funds, fixed income specialty [Member]
Defined benefit plan, fair value of pension plan assets	103.3	135.1
Fixed Income Investments [Member] | Registered mutual funds, fixed income specialty [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Fixed Income Investments [Member] | Registered mutual funds, fixed income specialty [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Fixed Income Investments [Member] | Registered mutual funds, fixed income specialty [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Fixed Income Investments [Member] | Registered mutual funds, fixed income specialty [Member] | Net Assets, Segment [Member]
Defined benefit plan, fair value of pension plan assets	103.3	135.1
Fixed Income Investments [Member] | U.S. Government and Agency Obligations [Member]
Defined benefit plan, fair value of pension plan assets	528.5	476.2
Fixed Income Investments [Member] | U.S. Government and Agency Obligations [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Fixed Income Investments [Member] | U.S. Government and Agency Obligations [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan, fair value of pension plan assets	528.5	476.2
Fixed Income Investments [Member] | U.S. Government and Agency Obligations [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Fixed Income Investments [Member] | U.S. Government and Agency Obligations [Member] | Net Assets, Segment [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Fixed Income Investments [Member] | Corporate and Non-U.S. Bonds [Member]
Defined benefit plan, fair value of pension plan assets	1,393.4	1,225.8
Fixed Income Investments [Member] | Corporate and Non-U.S. Bonds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Fixed Income Investments [Member] | Corporate and Non-U.S. Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan, fair value of pension plan assets	1,393.0	1,225.8
Fixed Income Investments [Member] | Corporate and Non-U.S. Bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan, fair value of pension plan assets	0.4	0.0
Fixed Income Investments [Member] | Corporate and Non-U.S. Bonds [Member] | Net Assets, Segment [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Fixed Income Investments [Member] | Asset-Backed And Mortgage-Backed Securities [Member]
Defined benefit plan, fair value of pension plan assets	70.9	67.3
Fixed Income Investments [Member] | Asset-Backed And Mortgage-Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Fixed Income Investments [Member] | Asset-Backed And Mortgage-Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan, fair value of pension plan assets	70.9	67.3
Fixed Income Investments [Member] | Asset-Backed And Mortgage-Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Fixed Income Investments [Member] | Asset-Backed And Mortgage-Backed Securities [Member] | Net Assets, Segment [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Fixed Income Investments [Member] | Commingled Funds - Fixed Income Specialty [Member]
Defined benefit plan, fair value of pension plan assets	127.6	117.7
Fixed Income Investments [Member] | Commingled Funds - Fixed Income Specialty [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Fixed Income Investments [Member] | Commingled Funds - Fixed Income Specialty [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Fixed Income Investments [Member] | Commingled Funds - Fixed Income Specialty [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Fixed Income Investments [Member] | Commingled Funds - Fixed Income Specialty [Member] | Net Assets, Segment [Member]
Defined benefit plan, fair value of pension plan assets	127.6	117.7
Fixed Income Investments [Member] | Other Fixed Income [Member]
Defined benefit plan, fair value of pension plan assets	26.0	24.8
Fixed Income Investments [Member] | Other Fixed Income [Member] | Fair Value, Inputs, Level 1 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Fixed Income Investments [Member] | Other Fixed Income [Member] | Fair Value, Inputs, Level 2 [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Fixed Income Investments [Member] | Other Fixed Income [Member] | Fair Value, Inputs, Level 3 [Member]
Defined benefit plan, fair value of pension plan assets	26.0	24.8
Fixed Income Investments [Member] | Other Fixed Income [Member] | Net Assets, Segment [Member]
Defined benefit plan, fair value of pension plan assets	0.0	0.0
Defined Benefit Plan Fair Value of Plan Assets Measured Using Net Asset Value [Member]
Defined benefit plan, fair value of pension plan assets	$ 3,127.6	$ 2,754.8