Indemnity Supplemental Information (Details) (USD $) In Millions, unless otherwise specified												12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2012 Erie Family Life Insurance Company (EFL)	Dec. 31, 2011 Erie Family Life Insurance Company (EFL)	Dec. 31, 2010 Erie Family Life Insurance Company (EFL)	Dec. 31, 2012 Indemnity	Dec. 31, 2011 Indemnity	Dec. 31, 2010 Indemnity	Dec. 31, 2009 Indemnity	Dec. 31, 2012 Indemnity Erie Family Life Insurance Company (EFL)	Dec. 31, 2011 Indemnity Erie Family Life Insurance Company (EFL)	Dec. 31, 2012 Exchange	Dec. 31, 2011 Exchange	Dec. 31, 2012 Reclassifications and eliminations	Dec. 31, 2011 Reclassifications and eliminations
Available-for-sale securities, at fair value:
Fixed maturities	$ 8,159	$ 7,840						$ 452	$ 548					$ 7,707	$ 7,292
Equity securities	1,000	589						55	25					945	564
Trading securities, at fair value	2,417	2,335						0	27					2,417	2,308
Limited partnerships	1,217	1,290						180	208					1,037	1,082
Other invested assets	21	20						1	1					20	19
Total investments	12,814	12,074						688	809					12,126	11,265
Cash and cash equivalents	400	185	430	234				12	11	310	76			388	174
Premiums receivable from policyholders	1,062	976												1,062	976
Reinsurance recoverable	168	166												168	166
Deferred income tax asset	37	19						37	19
Deferred acquisition costs	504	487												504	487
Other assets	456	441						117	119					339	322
Receivables from the Exchange and other affiliates								281	254			3	3			(281)	(254)
Note receivable from EFL								25	25							(25)	(25)
Total assets	15,441	14,348						1,160	1,237					14,587	13,390	(306)	(279)
Liabilities
Losses and loss expense reserves	3,598	3,499												3,598	3,499
Life policy and deposit contract reserves	1,708	1,671			1,708	1,671	1,603							1,708	1,671
Unearned premiums	2,365	2,178												2,365	2,178
Deferred income tax liability	365	147												365	147
Other liabilities, prior to consolidation eliminations	614	560						518	456					402	383	(306)	(279)
Total liabilities	8,650	8,055						518	456					8,438	7,878	(306)	(279)
Shareholders' equity and noncontrolling interest
Total Indemnity shareholders’ equity	642	781						642	781
Noncontrolling interest in consolidated entity – Exchange	6,149	5,512												6,149	5,512
Total equity	6,791	6,293	6,334					642	781					6,149	5,512
Total liabilities, shareholders’ equity and noncontrolling interest	15,441	14,348						1,160	1,237					14,587	13,390	(306)	(279)
Receivables from the Exchange								278	251
Note receivable from EFL, annual interest rate (as a percent)												6.70%
EFL annual interest paid to Indemnity												$ 2	$ 2