Incentive and Deferred Compensation Plans - Narrative (Details) $ / shares in Units, $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($) plan $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($)
Incentive and deferred compensation plans
Number of incentive plans for executives, senior vice presidents and other selected officers | plan		2
Number of deferred compensation plans for executives, senior vice presidents and other selected officers | plan		2
Number of deferred compensation plans for outside directors | plan		2
Annual incentive plan awards
Incentive and deferred compensation plans
Maximum percentage of employee compensation that can be deferred (as a percent)		100.00%
Long-term incentive plan awards
Incentive and deferred compensation plans
Maximum percentage of employee compensation that can be deferred (as a percent)		100.00%
Vesting period of performance and/or service condition(s)		3 years
Maximum dollar amount which may be received by any single participant during any specified period		$ 5.0
Compensation cost related to share-based compensation plan awards		3.4	$ 3.0	$ 12.0
Tax benefits recognized in income related to award expense		0.7	0.6	2.5
Total unrecognized compensation cost related to share-based compensation plan awards pertaining to open performance periods		$ 5.9
Expected period of recognition related to unrecognized compensation cost (in years)		2 years
Long-term incentive plan awards | Class A common stock
Incentive and deferred compensation plans
Maximum number of shares authorized for grant (in shares) | shares		1,500,000
Maximum number of shares which may be received by any single participant during any specified period (in shares) | shares		250,000
Long-term incentive plan awards | Performance Period Long Term Incentive Plan 2020 To 2022
Incentive and deferred compensation plans
Compensation cost related to share-based compensation plan awards	$ 5.4
Long-term incentive plan awards | Performance Period Long Term Incentive Plan 2019-2021
Incentive and deferred compensation plans
Compensation cost related to share-based compensation plan awards			$ 3.8
Long-term incentive plan awards | Performance Period Long-Term Incentive Plan 2018-2020
Incentive and deferred compensation plans
Compensation cost related to share-based compensation plan awards				$ 10.9
Long-term incentive plan awards | Performance Period Long Term Incentive Plan 2017-2019
Incentive and deferred compensation plans
Compensation cost related to share-based compensation plan awards					$ 7.4
Incentive compensation deferral plan | Class A common stock
Incentive and deferred compensation plans
Vesting percent of the grant in Class A common stock (as a percent)		100.00%
Payment period for vested share credits (in years)		3 years
Average price per share for shares purchased (in dollars per share) | $ / shares		$ 173.52	$ 232.81	$ 155.92
Total cost of shares purchased for share-based compensation awards		$ 0.5	$ 0.6	$ 0.6
Incentive compensation deferral plan | Class A common stock | Performance shares
Incentive and deferred compensation plans
Shares purchased for share-based compensation awards (in shares) | shares		2,879	2,570	3,934
Incentive compensation deferral plan | Performance Period Long Term Incentive Plan 2019-2021 | Class A common stock
Incentive and deferred compensation plans
Average price per share for shares purchased (in dollars per share) | $ / shares		$ 178.45
Total cost of shares purchased for share-based compensation awards		$ 0.7
Incentive compensation deferral plan | Performance Period Long Term Incentive Plan 2019-2021 | Class A common stock | Performance shares
Incentive and deferred compensation plans
Shares purchased for share-based compensation awards (in shares) | shares		4,167
Incentive compensation deferral plan | Performance Period Long-Term Incentive Plan 2018-2020 | Class A common stock
Incentive and deferred compensation plans
Average price per share for shares purchased (in dollars per share) | $ / shares			$ 191.25
Total cost of shares purchased for share-based compensation awards			$ 3.4
Incentive compensation deferral plan | Performance Period Long-Term Incentive Plan 2018-2020 | Class A common stock | Performance shares
Incentive and deferred compensation plans
Shares purchased for share-based compensation awards (in shares) | shares			17,881
Incentive compensation deferral plan | Performance Period Long Term Incentive Plan 2017-2019 | Class A common stock
Incentive and deferred compensation plans
Average price per share for shares purchased (in dollars per share) | $ / shares				$ 185.31
Total cost of shares purchased for share-based compensation awards				$ 3.4
Incentive compensation deferral plan | Performance Period Long Term Incentive Plan 2017-2019 | Class A common stock | Performance shares
Incentive and deferred compensation plans
Shares purchased for share-based compensation awards (in shares) | shares				18,126
Stock compensation plan for outside directors
Incentive and deferred compensation plans
Compensation cost related to share-based compensation plan awards		$ 0.8	$ 0.8	$ 0.9
Stock compensation plan for outside directors | Class A common stock
Incentive and deferred compensation plans
Average price per share for shares purchased (in dollars per share) | $ / shares		$ 201.93	$ 212.41	$ 201.78
Total cost of shares purchased for share-based compensation awards		$ 1.2	$ 1.1	$ 1.5
Stock compensation plan for outside directors | Class A common stock | Performance shares
Incentive and deferred compensation plans
Shares purchased for share-based compensation awards (in shares) | shares		6,048	5,238	7,401
Stock compensation plan for outside directors | Class A common stock | Three Month Vesting Period
Incentive and deferred compensation plans
Vesting period of performance and/or service condition(s)		3 months
Vesting percent of the grant in Class A common stock (as a percent)		25.00%
Equity compensation plan
Incentive and deferred compensation plans
Compensation cost related to share-based compensation plan awards		$ 0.8	$ 0.2	$ 0.7
Total unrecognized compensation cost related to share-based compensation plan awards pertaining to open performance periods		$ 1.3
Expected period of recognition related to unrecognized compensation cost (in years)		3 years
Equity compensation plan | Class A common stock
Incentive and deferred compensation plans
Maximum number of shares authorized for grant (in shares) | shares		100,000
Maximum number of shares which may be received by any single participant during any specified period (in shares) | shares		10,000
Equity compensation plan | Performance Period Equity Compensation Plan 2019 | Class A common stock
Incentive and deferred compensation plans
Average price per share for shares purchased (in dollars per share) | $ / shares		$ 190.68
Total cost of shares purchased for share-based compensation awards		$ 0.3
Equity compensation plan | Performance Period Equity Compensation Plan 2019 | Class A common stock | Performance shares
Incentive and deferred compensation plans
Shares purchased for share-based compensation awards (in shares) | shares		1,786
Equity compensation plan | Performance Period Equity Compensation Plan 2018 | Class A common stock
Incentive and deferred compensation plans
Average price per share for shares purchased (in dollars per share) | $ / shares			$ 242.01
Total cost of shares purchased for share-based compensation awards			$ 0.2
Equity compensation plan | Performance Period Equity Compensation Plan 2018 | Class A common stock | Performance shares
Incentive and deferred compensation plans
Shares purchased for share-based compensation awards (in shares) | shares			978
Equity compensation plan | Performance Period Equity Compensation Plan 2017 | Class A common stock
Incentive and deferred compensation plans
Average price per share for shares purchased (in dollars per share) | $ / shares				$ 165.82
Total cost of shares purchased for share-based compensation awards				$ 0.3
Equity compensation plan | Performance Period Equity Compensation Plan 2017 | Class A common stock | Performance shares
Incentive and deferred compensation plans
Shares purchased for share-based compensation awards (in shares) | shares				1,787
Erie Insurance Exchange (EIE) | Long-term incentive plan awards
Incentive and deferred compensation plans
Incentive plan compensation cost reimbursed to Indemnity from the Exchange and its subsidiaries (as a percent)		41.00%
Erie Insurance Exchange (EIE) | Equity compensation plan
Incentive and deferred compensation plans
Incentive plan compensation cost reimbursed to Indemnity from the Exchange and its subsidiaries (as a percent)		3.00%	33.00%	59.00%