Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenues
Premiums earned/life policy revenue									$ 4,898	$ 4,493	$ 4,214
Net investment income									422	438	433
Net realized investment gains (losses)									771	418	(4)
Net impairment losses recognized in earnings									(13)	0	(2)
Equity in earnings of limited partnerships									161	131	149
Service agreement and other revenue									32	32	34
Total revenues	1,697	1,577	1,426	1,571	1,372	1,460	1,160	1,520	6,271	5,512	4,824
Benefits and expenses
Insurance losses and loss expenses									3,467	3,480	3,444
Policy acquisition and underwriting expenses									1,237	1,133	1,022
Total benefits and expenses	1,227	1,179	1,163	1,135	1,207	1,190	1,230	986	4,704	4,613	4,466
Income (loss) from operations before income taxes and noncontrolling interest	470	398	263	436	165	270	(70)	534	1,567	899	358
Provision for income taxes									519	280	90
Net income (loss)	314	267	177	290	119	184	(38)	354	1,048	619	268
Operating segment | Management operations
Segment information
Indemnity's maximum management fee rate as a percent of premiums written and assumed by the Exchange (as a percent)									25.00%
Reduction in commission expense due to adjustment										6.0	0.5
Indemnity commission expense adjustment description									This amount represents the reimbursement by the North Carolina Reinsurance Facility (NCRF) for commissions Indemnity paid to agents on the surcharges collected on behalf of the NCRF which was incorrectly recorded as a benefit to the Exchange in prior periods.
Revenues
Management fee revenue									1,266	1,157	1,067
Service agreement and other revenue									31	31	33
Total revenues									1,297	1,188	1,100
Benefits and expenses
Cost of management operations									1,088	983	892
Total benefits and expenses									1,088	983	892
Income (loss) from operations before income taxes and noncontrolling interest									209	205	208
Provision for income taxes									73	72	73
Net income (loss)									136	133	135
Operating segment | Property and casualty insurance operations
Revenues
Premiums earned/life policy revenue									4,820	4,422	4,149
Total revenues									4,820	4,422	4,149
Benefits and expenses
Insurance losses and loss expenses									3,365	3,384	3,349
Policy acquisition and underwriting expenses									1,387	1,284	1,178
Total benefits and expenses									4,752	4,668	4,527
Income (loss) from operations before income taxes and noncontrolling interest									68	(246)	(378)
Provision for income taxes									24	(86)	(132)
Net income (loss)									44	(160)	(246)
Operating segment | Life insurance operations
Revenues
Premiums earned/life policy revenue									80	73	67
Service agreement and other revenue									1	1	1
Total revenues									81	74	68
Benefits and expenses
Insurance losses and loss expenses									107	101	100
Policy acquisition and underwriting expenses									37	31	27
Total benefits and expenses									144	132	127
Income (loss) from operations before income taxes and noncontrolling interest									(63)	(58)	(59)
Provision for income taxes									(22)	(20)	(21)
Net income (loss)									(41)	(38)	(38)
Operating segment | Life insurance operations | Erie Family Life Insurance Company (EFL)
Segment information
Total investment revenues									111	104	109
Benefits and expenses
Income (loss) from operations before income taxes and noncontrolling interest									48	46	50
Operating segment | Investment operations
Revenues
Net investment income									434	449	444
Net realized investment gains (losses)									771	418	(4)
Net impairment losses recognized in earnings									(13)	0	(2)
Equity in earnings of limited partnerships									161	131	149
Total revenues									1,353	998	587
Benefits and expenses
Income (loss) from operations before income taxes and noncontrolling interest									1,353	998	587
Provision for income taxes									444	314	170
Net income (loss)									909	684	417
Eliminations
Revenues
Premiums earned/life policy revenue									(2)	(2)	(2)
Net investment income									(12)	(11)	(11)
Management fee revenue									(1,266)	(1,157)	(1,067)
Total revenues									(1,280)	(1,170)	(1,080)
Benefits and expenses
Cost of management operations									(1,088)	(983)	(892)
Insurance losses and loss expenses									(5)	(5)	(5)
Policy acquisition and underwriting expenses									(187)	(182)	(183)
Total benefits and expenses									$ (1,280)	$ (1,170)	$ (1,080)