Indemnity Supplemental Information (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Available-for-sale securities, at fair value:
Fixed maturities	$ 9,571	$ 8,688
Equity securities	875	869
Trading securities, at fair value	3,223	3,202
Limited partnerships	979	1,086
Other invested assets	21	21
Total investments	14,669	13,866
Cash and cash equivalents	514	452	400	185
Premiums receivable from policyholders	1,281	1,167
Reinsurance recoverable	161	172
Deferred income tax asset	37	2
Deferred acquisition costs	595	566
Other assets	501	451
Total assets	17,758	16,676
Liabilities
Losses and loss expense reserves	3,853	3,747
Life policy and deposit contract reserves	1,812	1,758
Unearned premiums	2,834	2,598
Deferred income tax liability	490	450
Other liabilities, adjusted for consolidation presentation	786	573
Total liabilities	9,775	9,126
Shareholders' equity and noncontrolling interest
Total Indemnity shareholders’ equity	703	734
Noncontrolling interest in consolidated entity – Exchange	7,280	6,816
Total equity	7,983	7,550	6,791
Total liabilities, shareholders’ equity, and noncontrolling interest	17,758	16,676
Indemnity
Available-for-sale securities, at fair value:
Fixed maturities	564	526
Equity securities	25	50
Limited partnerships	113	146
Other invested assets	1	1
Total investments	703	723
Cash and cash equivalents	92	49	12	11
Deferred income tax asset	37	2
Other assets	127	114
Receivables from the Exchange and other affiliates	335	300
Note receivable from EFL	25	25
Total assets	1,319	1,213
Liabilities
Deferred income tax liability	0	0
Other liabilities, adjusted for consolidation presentation	616	479
Total liabilities	616	479
Shareholders' equity and noncontrolling interest
Total Indemnity shareholders’ equity	703	734
Total equity	703	734
Total liabilities, shareholders’ equity, and noncontrolling interest	1,319	1,213
Exchange
Available-for-sale securities, at fair value:
Fixed maturities	9,007	8,162
Equity securities	850	819
Trading securities, at fair value	3,223	3,202
Limited partnerships	866	940
Other invested assets	20	20
Total investments	13,966	13,143
Cash and cash equivalents	422	403
Premiums receivable from policyholders	1,281	1,167
Reinsurance recoverable	161	172
Deferred income tax asset	0	0
Deferred acquisition costs	595	566
Other assets	374	337
Total assets	16,799	15,788
Liabilities
Losses and loss expense reserves	3,853	3,747
Life policy and deposit contract reserves	1,812	1,758
Unearned premiums	2,834	2,598
Deferred income tax liability	490	450
Other liabilities, adjusted for consolidation presentation	530	419
Total liabilities	9,519	8,972
Shareholders' equity and noncontrolling interest
Noncontrolling interest in consolidated entity – Exchange	7,280	6,816
Total equity	7,280	6,816
Total liabilities, shareholders’ equity, and noncontrolling interest	16,799	15,788
Receivables from the Exchange	331	296
Erie Family Life Insurance Company (EFL)
Available-for-sale securities, at fair value:
Note receivable from EFL	25
Shareholders' equity and noncontrolling interest
Receivables from the Exchange	4	4
Note receivable from EFL, annual interest rate (as a percent)	6.70%
Note receivable from EFL, interest income recognized by Indemnity	2	2
Reclassifications and eliminations
Available-for-sale securities, at fair value:
Receivables from the Exchange and other affiliates	(335)	(300)
Note receivable from EFL	(25)	(25)
Total assets	(360)	(325)
Liabilities
Other liabilities, adjusted for consolidation presentation	(360)	(325)
Total liabilities	(360)	(325)
Shareholders' equity and noncontrolling interest
Total liabilities, shareholders’ equity, and noncontrolling interest	$ (360)	$ (325)