Related-Party Transactions (Dividends Received On Common Shares Reported As Net Investment Income) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Related-Party Transactions [Abstract]
Dividends received	$ 4,666	$ 4,666

Dividends received on common shares, reported as net investment income in consolidated statements of operations and comprehensive income (loss).

No definition available.

Name:	cik0000914748_DividendsReceivedOnCommonSharesReportedAsNetInvestmentIncomeInConsolidatedStatementsOfOperationsAndComprehensiveIncomeLoss
Namespace Prefix:	cik0000914748_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration