Deferred Charges, Goodwill And Other Assets, Net (Schedule Of Cash Flow Hedging, Derivative Financial Instruments On The Income Statement) (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Jun. 30, 2017
Jun. 30, 2016
Interest Expense [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)     $ (1,368) $ (1,740)
Interest And Other Investment Income (Loss) [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Amount of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion, Reclassification for Forecasted Transactions No Longer Probable of Occurring and Amount Excluded from Effectiveness Testing)     (32) (1,012)
Interest Rate Swap [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Amount of Gain or (Loss) Recognized in OCI on Derivative (Effective Portion)     $ (1,494) $ (10,994)
Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | Cash Flow Hedging [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Amount of Gain or (Loss) Recognized in OCI on Derivative (Effective Portion) $ (2,129) $ (3,807)    
Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | Interest Expense [Member] | Cash Flow Hedging [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion) (776) (893)    
Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | Interest And Other Investment Income (Loss) [Member] | Cash Flow Hedging [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Amount of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion, Reclassification for Forecasted Transactions No Longer Probable of Occurring and Amount Excluded from Effectiveness Testing) $ 11 $ (99)