Summary of Investments Other Than Investments In Related Parties (Details) $ in Millions	Dec. 31, 2023 USD ($)
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	$ 19,220
Fair value	0
Balance sheet	25,357
Fixed Maturities
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	14,361
Fair value	13,791
Balance sheet	13,791
Equity Securities
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	4,282
Fair value	10,989
Balance sheet	10,989
Other than Securities Investment
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	577
Fair value	0
Balance sheet	577
States, Municipalities and Political Subdivisions | Fixed Maturities
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	4,867
Fair value	4,703
Balance sheet	4,703
States, Municipalities and Political Subdivisions | Fixed Maturities | Cincinnati Financial Corporation
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	54
Fair value	47
Balance sheet	47
States, Municipalities and Political Subdivisions | Fixed Maturities | The Cincinnati Insurance Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	3,339
Fair value	3,278
Balance sheet	3,278
States, Municipalities and Political Subdivisions | Fixed Maturities | The Cincinnati Casualty Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	239
Fair value	231
Balance sheet	231
States, Municipalities and Political Subdivisions | Fixed Maturities | The Cincinnati Indemnity Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	50
Fair value	49
Balance sheet	49
States, Municipalities and Political Subdivisions | Fixed Maturities | The Cincinnati Life Insurance Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	447
Fair value	388
Balance sheet	388
States, Municipalities and Political Subdivisions | Fixed Maturities | The Cincinnati Specialty Underwriters Insurance Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	738
Fair value	710
Balance sheet	710
United States Government | Fixed Maturities
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	203
Fair value	200
Balance sheet	200
United States Government | Fixed Maturities | The Cincinnati Insurance Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	122
Fair value	119
Balance sheet	119
United States Government | Fixed Maturities | The Cincinnati Casualty Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	1
Fair value	1
Balance sheet	1
United States Government | Fixed Maturities | The Cincinnati Indemnity Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	1
Fair value	1
Balance sheet	1
United States Government | Fixed Maturities | Cincinnati Global
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	79
Fair value	79
Balance sheet	79
Government-Sponsored Enterprises | Fixed Maturities
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	1,227
Fair value	1,224
Balance sheet	1,224
Government-Sponsored Enterprises | Fixed Maturities | Cincinnati Financial Corporation
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	103
Fair value	103
Balance sheet	103
Government-Sponsored Enterprises | Fixed Maturities | The Cincinnati Insurance Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	641
Fair value	641
Balance sheet	641
Government-Sponsored Enterprises | Fixed Maturities | The Cincinnati Casualty Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	25
Fair value	25
Balance sheet	25
Government-Sponsored Enterprises | Fixed Maturities | The Cincinnati Indemnity Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	6
Fair value	6
Balance sheet	6
Government-Sponsored Enterprises | Fixed Maturities | The Cincinnati Life Insurance Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	320
Fair value	318
Balance sheet	318
Government-Sponsored Enterprises | Fixed Maturities | The Cincinnati Specialty Underwriters Insurance Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	126
Fair value	126
Balance sheet	126
Government-Sponsored Enterprises | Fixed Maturities | Cincinnati Global
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	6
Fair value	5
Balance sheet	5
Foreign Government | Fixed Maturities
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	25
Fair value	25
Balance sheet	25
Foreign Government | Fixed Maturities | Cincinnati Global
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	25
Fair value	25
Balance sheet	25
All Other Corporate Bonds | Fixed Maturities
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	8,039
Fair value	7,639
Balance sheet	7,639
All Other Corporate Bonds | Fixed Maturities | Cincinnati Financial Corporation
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	27
Fair value	26
Balance sheet	26
All Other Corporate Bonds | Fixed Maturities | The Cincinnati Insurance Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	4,147
Fair value	3,955
Balance sheet	3,955
All Other Corporate Bonds | Fixed Maturities | The Cincinnati Casualty Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	98
Fair value	89
Balance sheet	89
All Other Corporate Bonds | Fixed Maturities | The Cincinnati Indemnity Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	35
Fair value	33
Balance sheet	33
All Other Corporate Bonds | Fixed Maturities | The Cincinnati Life Insurance Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	3,176
Fair value	3,005
Balance sheet	3,005
All Other Corporate Bonds | Fixed Maturities | The Cincinnati Specialty Underwriters Insurance Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	398
Fair value	373
Balance sheet	373
All Other Corporate Bonds | Fixed Maturities | Cincinnati Global
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	158
Fair value	158
Balance sheet	158
Common Stock | Equity Securities
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	3,869
Fair value	10,641
Balance sheet	10,641
Common Stock | Equity Securities | Cincinnati Financial Corporation
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	1,642
Fair value	4,542
Balance sheet	4,542
Common Stock | Equity Securities | The Cincinnati Insurance Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	2,025
Fair value	5,558
Balance sheet	5,558
Common Stock | Equity Securities | The Cincinnati Casualty Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	58
Fair value	171
Balance sheet	171
Common Stock | Equity Securities | The Cincinnati Indemnity Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	18
Fair value	40
Balance sheet	40
Common Stock | Equity Securities | The Cincinnati Specialty Underwriters Insurance Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	109
Fair value	302
Balance sheet	302
Common Stock | Equity Securities | CSU Producers Resources Inc.
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	17
Fair value	28
Balance sheet	28
Nonredeemable Preferred Stock | Equity Securities
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	413
Fair value	348
Balance sheet	348
Nonredeemable Preferred Stock | Equity Securities | Cincinnati Financial Corporation
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	3
Fair value	2
Balance sheet	2
Nonredeemable Preferred Stock | Equity Securities | The Cincinnati Insurance Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	397
Fair value	334
Balance sheet	334
Nonredeemable Preferred Stock | Equity Securities | The Cincinnati Life Insurance Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	13
Fair value	12
Balance sheet	12
Policy Loans | Other than Securities Investment | The Cincinnati Life Insurance Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	33
Fair value	0
Balance sheet	33
Lloyd's and other deposits | Other than Securities Investment | Cincinnati Financial Corporation
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	5
Fair value	0
Balance sheet	5
Lloyd's and other deposits | Other than Securities Investment | Cincinnati Global
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	39
Fair value	0
Balance sheet	39
Limited Partnership | Other than Securities Investment | Cincinnati Financial Corporation
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	40
Fair value	0
Balance sheet	40
Limited Partnership | Other than Securities Investment | The Cincinnati Insurance Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	389
Balance sheet	389
Limited Partnership | Other than Securities Investment | The Cincinnati Life Insurance Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	5
Balance sheet	5
Real Estate | Other than Securities Investment | Cincinnati Financial Corporation
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	4
Balance sheet	4
Real Estate | Other than Securities Investment | The Cincinnati Insurance Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	58
Balance sheet	58
Real Estate | Other than Securities Investment | The Cincinnati Life Insurance Company
Summary Of Investments Other Than Investments In Related Parties Reportable Data
Cost or amortized cost	4
Balance sheet	$ 4