Related-Party Transactions (Liability Limits For Any Losses Per One Occurrence) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
Sep. 30, 2012
Related-Party Transactions [Abstract]
Liability Limits, Losses per one occurrence, Exceeding	$ 100,000
Liability Limits, Losses per one occurrence, Not to Exceed	$ 150,000

Liability limits losses per one occurrence, not to exceed.

No definition available.

Name:	cik0000914748_LiabilityLimitsLossesPerOneOccurrenceNotToExceed
Namespace Prefix:	cik0000914748_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration