Financial Derivatives (Schedule Of Credit Derivatives) (Details) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
Credit Default Swap, Selling Protection [Member]
Credit Derivatives [Line Items]
Fair Value of Written Credit Derivatives, Net		$ (705)	$ (1,551)
Notional value	[1]	158,397	117,476
Credit Default Swap, Buying Protection [Member]
Credit Derivatives [Line Items]
Fair Value of Written Credit Derivatives, Net	[2]	756	4,552
Notional value	[2]	$ 90,411	$ 68,357

[1] The notional value is the maximum amount that a seller of credit protection would be obligated to pay, and a buyer of credit protection would receive upon occurrence of a "credit event." Movements in the value of credit default swap transactions may require the Company or the counterparty to post or receive collateral. Amounts due or owed under credit derivative contracts with an International Swaps and Derivatives Association, or "ISDA," counterparty may be offset against amounts due or owed on other credit derivative contracts with the same ISDA counterparty. As a result, the notional value of written credit derivatives involving a particular underlying reference asset or index has been reduced (but not below zero) by the notional value of any contracts where the Company has purchased credit protection on the same reference asset or index with the same ISDA counterparty.

[2] Offsetting transactions with third parties include purchased credit derivatives which have the same reference obligation.