Indemnity Supplemental Information (Details) (USD $) In Millions, unless otherwise specified												9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2014 Indemnity	Dec. 31, 2013 Indemnity	Sep. 30, 2013 Indemnity	Dec. 31, 2012 Indemnity	Sep. 30, 2014 Exchange	Dec. 31, 2013 Exchange	Dec. 31, 2012 Exchange	Sep. 30, 2014 Erie Family Life Insurance Company (EFL)	Sep. 30, 2013 Erie Family Life Insurance Company (EFL)	Dec. 31, 2013 Erie Family Life Insurance Company (EFL)	Sep. 30, 2014 Reclassifications and eliminations	Dec. 31, 2013 Reclassifications and eliminations
Available-for-sale securities, at fair value:
Fixed maturities	$ 9,465	$ 8,688			$ 563	$ 526			$ 8,902	$ 8,162
Equity securities	942	869			25	50			917	819
Trading securities, at fair value	3,125	3,202							3,125	3,202
Limited partnerships	1,073	1,086			134	146			939	940
Other invested assets	21	21			1	1			20	20
Total investments	14,626	13,866			723	723			13,903	13,143
Cash and cash equivalents	379	452	535	400	45	49	33	12	334	403
Premiums receivable from policyholders	1,323	1,167							1,323	1,167
Reinsurance recoverable	165	172							165	172
Deferred income tax asset	2	2			2	2			0	0
Deferred acquisition costs	603	566							603	566
Other assets	480	451			114	114			366	337
Receivables from the Exchange and other affiliates					343	300									(343)	(300)
Note receivable from EFL					25	25						25			(25)	(25)
Total assets	17,578	16,676			1,252	1,213			16,694	15,788					(368)	(325)
Liabilities
Losses and loss expense reserves	3,933	3,747							3,933	3,747
Life policy and deposit contract reserves	1,801	1,758							1,801	1,758
Unearned premiums	2,896	2,598							2,896	2,598
Deferred income tax liability	465	450			0	0			465	450
Other liabilities, adjusted for consolidation presentation	647	573			481	479			534	419					(368)	(325)
Total liabilities	9,742	9,126			481	479			9,629	8,972					(368)	(325)
Shareholders' equity and noncontrolling interest
Total Indemnity shareholders' equity	771	734			771	734
Noncontrolling interest in consolidated entity - Exchange	7,065	6,816							7,065	6,816
Total equity	7,836	7,550		6,791	771	734		642	7,065	6,816	6,149
Total liabilities, shareholders' equity, and noncontrolling interest	17,578	16,676			1,252	1,213			16,694	15,788					(368)	(325)
Receivables from the Exchange and EFL									340	296		3		4
Note receivable from EFL, annual interest rate (as a percent)												6.70%
Note receivable from EFL, interest income recognized by Indemnity												$ 1.3	$ 1.3