Leases (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Operating lease costs	$ 3,300	$ 3,600	$ 6,700	$ 7,200
Erie Insurance Exchange
Lessee, Lease, Description [Line Items]
Operating lease costs, amount reimbursed from Exchange and its subsidiaries	1,400	$ 1,600	2,800	$ 3,100
Erie Insurance Exchange | Office Space
Lessee, Lease, Description [Line Items]
Operating lease assets	9,200		9,200
Operating lease assets
Lessee, Lease, Description [Line Items]
Operating lease assets	19,267		19,267		$ 22,401
Operating lease liabilities - current
Lessee, Lease, Description [Line Items]
Operating lease liabilities - current	11,216		11,216		11,289
Operating lease liabilities - long-term
Lessee, Lease, Description [Line Items]
Operating lease liabilities - long-term	7,664		7,664		10,665
Operating lease liabilities
Lessee, Lease, Description [Line Items]
Total operating lease liabilities	$ 18,880		$ 18,880		$ 21,954