Deferred Policy Acquisition Costs (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Components of the Property and Casualty Group's and EFL's deferred policy acquisition costs assets
Deferred policy acquisition costs asset at beginning of year	$ 487
Amortized deferred policy acquisition costs	(715)	(680)	(652)
Deferred policy acquisition costs asset at end of year	504	487
Property and Casualty Group
Components of the Property and Casualty Group's and EFL's deferred policy acquisition costs assets
Deferred policy acquisition costs asset at beginning of year	343	327
Capitalized deferred policy acquisition costs	726	684
Amortized deferred policy acquisition costs	(705)	(668)
Deferred policy acquisition costs asset at end of year	364	343
Erie Family Life Insurance Company (EFL)
Components of the Property and Casualty Group's and EFL's deferred policy acquisition costs assets
Deferred policy acquisition costs asset at beginning of year	144	140
Capitalized deferred policy acquisition costs	17	18
Amortized deferred policy acquisition costs	(10)	(12)
Change in shadow deferred policy acquisition costs	(11)	(2)
Deferred policy acquisition costs asset at end of year	$ 140	$ 144