Reinsurance (Details) (USD $)	12 Months Ended
	Dec. 31, 2011 Life Insurance in Force Erie Family Life Insurance Company ("EFL")	Dec. 31, 2010 Life Insurance in Force Erie Family Life Insurance Company ("EFL")	Dec. 31, 2012 Property and Casualty Group	Dec. 31, 2011 Property and Casualty Group	Dec. 31, 2011 Property and Casualty Group Minimum D	Dec. 31, 2012 Property and Casualty Group Maximum	Dec. 31, 2011 Property and Casualty Group Maximum D	Dec. 31, 2011 Erie Insurance Company Property and Casualty Group	Dec. 31, 2011 Erie Insurance Company of New York Property and Casualty Group	Dec. 31, 2011 Exchange Property and Casualty Group
Reinsurance
Reinsurance pooling agreement, participation (as a percent)								5.00%	0.50%	94.50%
Reinsurance pooling agreement, termination notice period (in days)					90
Reinsurance pooling agreement, intercompany cash settlement period (in days)							30
Coverage under the first property catastrophe treaty as a percentage of the loss coverage amount							90.00%
Loss coverage amount, under first property catastrophe treaty, in excess of the Property & Casualty Groups retention per occurrence				$ 500,000,000
Property & Casualty Group's retention per occurrence on first property catastrophe treaty				350,000,000
Coverage under the second property catastrophe treaty as a percentage of the loss coverage amount							90.00%
Loss coverage amount, under second property catastrophe treaty, in excess of $850,000,000				25,000,000
Loss threshold for second property catastrophe treaty to be triggered				850,000,000
Coverage under the first property catastrophe treaty as a percentage of the loss coverage amount						90.00%
Loss coverage amount, under first property catastrophe treaty, in excess of the Property & Casualty Group's retention per occurrence			500,000,000
Property & Casualty Group's retention per occurrence on renewed property catastrophe treaty			350,000,000
Coverage under the second property catastrophe treaty as a percentage of the loss coverage amount						70.00%
Loss coverage amount, under second property catastrophe treaty, in excess of $850,000,000			275,000,000
Loss threshold for second property catastrophe treaty to be triggered			850,000,000
Coverage under the third property catastrophe treaty as a percentage of the loss coverage amount						70.00%
Loss coverage amount, under third property catastrophe treaty, in excess of $1,125,000,000			25,000,000
Loss threshold for third property catastrophe treaty to be triggered			1,125,000,000
Direct life insurance in force	42,000,000,000	40,000,000,000
Ceded life insurance in force	23,000,000,000	22,000,000,000
Largest amount of in force life insurance ceded to a single reinsurer	$ 11,000,000,000	$ 11,000,000,000