Annual report pursuant to Section 13 and 15(d)

Deferred Charges, Goodwill And Other Assets, Net (Narrative) (Details)

v3.8.0.1
Deferred Charges, Goodwill And Other Assets, Net (Narrative) (Details) - USD ($)
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Credit Risk Contract [Member]      
Derivative Instruments, Gain (Loss) [Line Items]      
Net liability $ 0    
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member]      
Derivative Instruments, Gain (Loss) [Line Items]      
Derivative notional amount 675,000,000    
Ineffective gain (loss) in interest expense (37,000) $ 600,000 $ 0
Estimated additional amount to be reclassified to interest expense 1,500,000    
Not Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member]      
Derivative Instruments, Gain (Loss) [Line Items]      
Amount of increase in the fair value of derivatives $ 0 $ 2,000 $ 93,000