Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Revenues
Premiums earned/life policy revenue	$ 1,355	$ 1,241	$ 3,962	$ 3,631
Net investment income	115	109	335	316
Net realized investment (losses) gains	(85)	191	104	501
Net impairment losses recognized in earnings	(1)	(9)	(1)	(10)
Equity in earnings of limited partnerships	34	37	111	112
Service agreement and other revenue	8	8	24	24
Total revenues	1,426	1,577	4,535	4,574
Benefits and expenses
Insurance losses and loss expenses	935	868	3,095	2,571
Policy acquisition and underwriting expenses	341	311	987	906
Total benefits and expenses	1,276	1,179	4,082	3,477
Income (loss) from operations before income taxes and noncontrolling interest	150	398	453	1,097
Provision for income taxes	42	131	133	363
Net income (loss)	108	267	320	734	1,048
Indemnity
Revenues
Net investment income	4	4	12	11
Net realized investment (losses) gains	0	1	1	1
Net impairment losses recognized in earnings	0	0	0	0
Equity in earnings of limited partnerships	4	5	13	13
Benefits and expenses
Income (loss) from operations before income taxes and noncontrolling interest	70	70	214	193
Provision for income taxes	23	24	72	66
Net income (loss)			142		163
Exchange
Revenues
Net investment income	111	105	323	305
Net realized investment (losses) gains	(85)	190	103	500
Net impairment losses recognized in earnings	(1)	(9)	(1)	(10)
Equity in earnings of limited partnerships	30	32	98	99
Benefits and expenses
Net income (loss)			178		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	362	333	1,047	965
Service agreement and other revenue	8	8	23	23
Total revenues	370	341	1,070	988
Benefits and expenses
Cost of management operations	308	281	882	820
Income (loss) from operations before income taxes and noncontrolling interest	62	60	188	168
Investment operations | Indemnity
Revenues
Net investment income	4	4	12	11
Net realized investment (losses) gains	0	1	1	1
Net impairment losses recognized in earnings	0	0	0	0
Equity in earnings of limited partnerships	4	5	13	13
Benefits and expenses
Income (loss) from operations before income taxes and noncontrolling interest	8	10	26	25
Operating segment | Management operations
Revenues
Management fee revenue	362	333	1,047	965
Service agreement and other revenue	8	8	23	23
Total revenues	370	341	1,070	988
Benefits and expenses
Cost of management operations	308	281	882	820
Total benefits and expenses	308	281	882	820
Income (loss) from operations before income taxes and noncontrolling interest	62	60	188	168
Provision for income taxes	22	21	66	59
Net income (loss)	40	39	122	109
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	1,333	1,221	3,899	3,573
Total revenues	1,333	1,221	3,899	3,573
Benefits and expenses
Insurance losses and loss expenses	908	841	3,016	2,495
Policy acquisition and underwriting expenses	387	356	1,132	1,032
Total benefits and expenses	1,295	1,197	4,148	3,527
Income (loss) from operations before income taxes and noncontrolling interest	38	24	(249)	46
Provision for income taxes	13	8	(87)	16
Net income (loss)	25	16	(162)	30
Operating segment | Life insurance operations
Revenues
Premiums earned/life policy revenue	22	21	64	60
Service agreement and other revenue	0	0	1	1
Total revenues	22	21	65	61
Benefits and expenses
Insurance losses and loss expenses	28	28	83	80
Policy acquisition and underwriting expenses	10	9	28	25
Total benefits and expenses	38	37	111	105
Income (loss) from operations before income taxes and noncontrolling interest	(16)	(16)	(46)	(44)
Provision for income taxes	(5)	(5)	(16)	(15)
Net income (loss)	(11)	(11)	(30)	(29)
Operating segment | Life insurance operations | Erie Family Life Insurance Company (EFL)
Segment information
Total investment revenues	26	26	79	78
Benefits and expenses
Income (loss) from operations before income taxes and noncontrolling interest	10	10	33	34
Operating segment | Investment operations
Revenues
Net investment income	118	111	346	324
Net realized investment (losses) gains	(85)	191	104	501
Net impairment losses recognized in earnings	(1)	(9)	(1)	(10)
Equity in earnings of limited partnerships	34	37	111	112
Total revenues	66	330	560	927
Benefits and expenses
Income (loss) from operations before income taxes and noncontrolling interest	66	330	560	927
Provision for income taxes	12	107	170	303
Net income (loss)	54	223	390	624
Eliminations
Revenues
Premiums earned/life policy revenue	0	(1)	(1)	(2)
Net investment income	(3)	(2)	(11)	(8)
Management fee revenue	(362)	(333)	(1,047)	(965)
Total revenues	(365)	(336)	(1,059)	(975)
Benefits and expenses
Cost of management operations	(308)	(281)	(882)	(820)
Insurance losses and loss expenses	(1)	(1)	(4)	(4)
Policy acquisition and underwriting expenses	(56)	(54)	(173)	(151)
Total benefits and expenses	$ (365)	$ (336)	$ (1,059)	$ (975)