Related-Party Transactions (Dividends Received On Common Shares Reported As Net Investment Income) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Related-Party Transactions [Abstract]
Dividends received	$ 4,666	$ 4,665	$ 13,997	$ 13,979

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

No definition available.

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