Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Revenues
Premiums earned/life policy revenue	$ 1,319	$ 1,215	$ 2,607	$ 2,390
Net investment income	111	104	220	207
Net realized investment gains	133	61	189	310
Net impairment losses recognized in earnings	0	(1)	0	(1)
Equity in earnings of limited partnerships	27	39	77	75
Service agreement and other revenue	8	8	16	16
Total revenues	1,598	1,426	3,109	2,997
Benefits and expenses
Insurance losses and loss expenses	1,126	861	2,160	1,703
Policy acquisition and underwriting expenses	325	302	646	595
Total benefits and expenses	1,451	1,163	2,806	2,298
Income (loss) from operations before income taxes and noncontrolling interest	147	263	303	699
Provision for income taxes	44	86	91	232
Net income (loss)	103	177	212	467	1,048
Indemnity
Revenues
Net investment income	4	3	8	7
Net realized investment gains	0	0	1	0
Equity in earnings of limited partnerships	3	5	9	8
Benefits and expenses
Income (loss) from operations before income taxes and noncontrolling interest	75	67	144	123
Provision for income taxes	26	23	49	42
Net income (loss)			95		163
Exchange
Revenues
Net investment income	107	101	212	200
Net realized investment gains	133	61	188	310
Equity in earnings of limited partnerships	24	34	68	67
Benefits and expenses
Net income (loss)			117		885
Management operations | Indemnity
Segment information
Indemnity's maximum management fee rate as a percent of premiums written and assumed by the Exchange (as a percent)			25.00%
Revenues
Management fee revenue	366	336	685	632
Service agreement and other revenue	8	8	15	15
Total revenues	374	344	700	647
Benefits and expenses
Cost of management operations	306	285	574	539
Income (loss) from operations before income taxes and noncontrolling interest	68	59	126	108
Investment operations | Indemnity
Revenues
Net investment income	4	3	8	7
Net realized investment gains	0	0	1	0
Net impairment losses recognized in earnings	0	0	0	0
Equity in earnings of limited partnerships	3	5	9	8
Benefits and expenses
Income (loss) from operations before income taxes and noncontrolling interest	7	8	18	15
Operating segment | Management operations
Revenues
Management fee revenue	366	336	685	632
Service agreement and other revenue	8	8	15	15
Total revenues	374	344	700	647
Benefits and expenses
Cost of management operations	306	285	574	539
Total benefits and expenses	306	285	574	539
Income (loss) from operations before income taxes and noncontrolling interest	68	59	126	108
Provision for income taxes	24	21	44	38
Net income (loss)	44	38	82	70
Operating segment | Management operations | Indemnity
Segment information
Indemnity's maximum management fee rate as a percent of premiums written and assumed by the Exchange (as a percent)			25.00%
Operating segment | Property and casualty insurance operations
Revenues
Premiums earned/life policy revenue	1,298	1,196	2,566	2,352
Total revenues	1,298	1,196	2,566	2,352
Benefits and expenses
Insurance losses and loss expenses	1,101	837	2,108	1,654
Policy acquisition and underwriting expenses	380	348	745	676
Total benefits and expenses	1,481	1,185	2,853	2,330
Income (loss) from operations before income taxes and noncontrolling interest	(183)	11	(287)	22
Provision for income taxes	(64)	4	(100)	8
Net income (loss)	(119)	7	(187)	14
Operating segment | Life insurance operations
Revenues
Premiums earned/life policy revenue	22	20	42	39
Service agreement and other revenue	0	0	1	1
Total revenues	22	20	43	40
Benefits and expenses
Insurance losses and loss expenses	27	26	55	52
Policy acquisition and underwriting expenses	9	7	18	16
Total benefits and expenses	36	33	73	68
Income (loss) from operations before income taxes and noncontrolling interest	(14)	(13)	(30)	(28)
Provision for income taxes	(5)	(5)	(11)	(10)
Net income (loss)	(9)	(8)	(19)	(18)
Operating segment | Life insurance operations | Erie Family Life Insurance Company (EFL)
Segment information
Total investment revenues	24	26	53	52
Benefits and expenses
Income (loss) from operations before income taxes and noncontrolling interest	10	13	23	24
Operating segment | Investment operations
Revenues
Net investment income	116	107	228	213
Net realized investment gains	133	61	189	310
Net impairment losses recognized in earnings	0	(1)	0	(1)
Equity in earnings of limited partnerships	27	39	77	75
Total revenues	276	206	494	597
Benefits and expenses
Income (loss) from operations before income taxes and noncontrolling interest	276	206	494	597
Provision for income taxes	89	66	158	196
Net income (loss)	187	140	336	401
Eliminations
Revenues
Premiums earned/life policy revenue	(1)	(1)	(1)	(1)
Net investment income	(5)	(3)	(8)	(6)
Management fee revenue	(366)	(336)	(685)	(632)
Total revenues	(372)	(340)	(694)	(639)
Benefits and expenses
Cost of management operations	(306)	(285)	(574)	(539)
Insurance losses and loss expenses	(2)	(2)	(3)	(3)
Policy acquisition and underwriting expenses	(64)	(53)	(117)	(97)
Total benefits and expenses	$ (372)	$ (340)	$ (694)	$ (639)