Fair Value Measurements - Fair Value Inputs (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	$ 6,998.5	$ 6,922.1
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	709.8	907.3
Investments in Fixed Maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value		6,922.1
U.S. Government and Government Agencies and Authorities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	760.6	815.9
States and Political Subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	1,529.0	1,515.8
Foreign Governments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	5.0	16.8
Bonds and Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	3,934.0	3,859.7
Redeemable Preferred Stocks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	6.7	6.7
Collateralized Loan Obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	593.5	618.2
Other Mortgage- and Asset-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	169.7	89.0
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible debt at fair value	32.8	37.3
Total	7,741.1	7,866.7
Fair Value, Measurements, Recurring | Investments in Fixed Maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	6,998.5	6,922.1
Fair Value, Measurements, Recurring | U.S. Government and Government Agencies and Authorities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	760.6	815.9
Fair Value, Measurements, Recurring | States and Political Subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	1,529.0	1,515.8
Fair Value, Measurements, Recurring | Foreign Governments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	5.0	16.8
Fair Value, Measurements, Recurring | Bonds and Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	3,934.0	3,859.7
Fair Value, Measurements, Recurring | Redeemable Preferred Stocks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	6.7
Fair Value, Measurements, Recurring | Collateralized Loan Obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	593.5	618.2
Fair Value, Measurements, Recurring | Other Mortgage- and Asset-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	169.7	89.0
Fair Value, Measurements, Recurring | Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	709.8	907.3
Fair Value, Measurements, Recurring | Exchange Traded Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	374.7	586.8
Fair Value, Measurements, Recurring | Limited Liability Companies and Limited Partnerships
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	275.1	248.1
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible debt at fair value	0.0	0.0
Total	535.9	745.0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Investments in Fixed Maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	151.3	144.3
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Government and Government Agencies and Authorities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	151.3	144.3
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | States and Political Subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	0.0	0.0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Foreign Governments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	0.0	0.0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Bonds and Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	0.0	0.0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Redeemable Preferred Stocks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		0.0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Redeemable Preferred Stocks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	0.0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Collateralized Loan Obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	0.0	0.0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Mortgage- and Asset-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	0.0	0.0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	384.6	600.7
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Exchange Traded Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	374.7	586.8
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Limited Liability Companies and Limited Partnerships
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	0.0	0.0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible debt at fair value	32.8	37.3
Total	6,444.8	5,829.4
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Investments in Fixed Maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	6,361.9	5,733.6
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | U.S. Government and Government Agencies and Authorities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	609.3	671.6
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | States and Political Subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	1,528.3	1,515.8
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Foreign Governments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	5.0	16.8
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Bonds and Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	3,543.4	3,450.6
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Redeemable Preferred Stocks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		0.0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Redeemable Preferred Stocks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value		0.0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Collateralized Loan Obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	515.6	0.0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Other Mortgage- and Asset-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	160.3	78.8
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	50.1	58.5
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Exchange Traded Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	0.0	0.0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Limited Liability Companies and Limited Partnerships
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	0.0	0.0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible debt at fair value	0.0	0.0
Total	485.3	1,044.2
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Investments in Fixed Maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	485.3	1,044.2
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | U.S. Government and Government Agencies and Authorities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	0.0	0.0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | States and Political Subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	0.7	0.0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Foreign Governments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	0.0	0.0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Bonds and Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	390.6	409.1
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Redeemable Preferred Stocks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities		6.7
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Redeemable Preferred Stocks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value		6.7
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Collateralized Loan Obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	77.9	618.2
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Other Mortgage- and Asset-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	9.4	10.2
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	0.0	0.0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Exchange Traded Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	0.0	0.0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Limited Liability Companies and Limited Partnerships
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	0.0	0.0
Finance, Insurance and Real Estate | Fair Value, Measurements, Recurring | Preferred Stocks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	38.6	44.5
Finance, Insurance and Real Estate | Fair Value, Measurements, Recurring | Common Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	9.0	12.8
Finance, Insurance and Real Estate | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Preferred Stocks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	0.0	0.0
Finance, Insurance and Real Estate | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Common Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	9.0	12.8
Finance, Insurance and Real Estate | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Preferred Stocks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	38.6	44.5
Finance, Insurance and Real Estate | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Common Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	0.0	0.0
Finance, Insurance and Real Estate | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Preferred Stocks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	0.0	0.0
Finance, Insurance and Real Estate | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Common Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	0.0	0.0
Other Industries | Fair Value, Measurements, Recurring | Preferred Stocks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	12.2	14.7
Other Industries | Fair Value, Measurements, Recurring | Common Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	0.2	0.4
Other Industries | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Preferred Stocks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	0.8	0.9
Other Industries | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Common Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	0.1	0.2
Other Industries | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Preferred Stocks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	11.4	13.8
Other Industries | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Common Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	0.1	0.2
Other Industries | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Preferred Stocks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	0.0	0.0
Other Industries | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Common Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	0.0	0.0
Measured at Net Asset Value | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible debt at fair value	0.0	0.0
Total	275.1	248.1
Measured at Net Asset Value | Fair Value, Measurements, Recurring | Investments in Fixed Maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	0.0	0.0
Measured at Net Asset Value | Fair Value, Measurements, Recurring | U.S. Government and Government Agencies and Authorities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	0.0	0.0
Measured at Net Asset Value | Fair Value, Measurements, Recurring | States and Political Subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	0.0	0.0
Measured at Net Asset Value | Fair Value, Measurements, Recurring | Foreign Governments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	0.0	0.0
Measured at Net Asset Value | Fair Value, Measurements, Recurring | Bonds and Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	0.0	0.0
Measured at Net Asset Value | Fair Value, Measurements, Recurring | Redeemable Preferred Stocks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value		6.7
Available-for-sale Securities		0.0
Measured at Net Asset Value | Fair Value, Measurements, Recurring | Redeemable Preferred Stocks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value		0.0
Measured at Net Asset Value | Fair Value, Measurements, Recurring | Collateralized Loan Obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	0.0	0.0
Measured at Net Asset Value | Fair Value, Measurements, Recurring | Other Mortgage- and Asset-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed maturities at fair value	0.0	0.0
Measured at Net Asset Value | Fair Value, Measurements, Recurring | Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	275.1	248.1
Measured at Net Asset Value | Fair Value, Measurements, Recurring | Exchange Traded Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	0.0	0.0
Measured at Net Asset Value | Fair Value, Measurements, Recurring | Limited Liability Companies and Limited Partnerships
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	275.1	248.1
Measured at Net Asset Value | Finance, Insurance and Real Estate | Fair Value, Measurements, Recurring | Preferred Stocks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	0.0	0.0
Measured at Net Asset Value | Finance, Insurance and Real Estate | Fair Value, Measurements, Recurring | Common Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	0.0	0.0
Measured at Net Asset Value | Other Industries | Fair Value, Measurements, Recurring | Preferred Stocks
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	0.0	0.0
Measured at Net Asset Value | Other Industries | Fair Value, Measurements, Recurring | Common Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Securities at Fair Value (Cost: 2020 - $698.0; 2019 - $818.8)	$ 0.0	$ 0.0