Quarterly report pursuant to Section 13 or 15(d)

Disclosure Of Fair Value Of Assets And Liabilities (Narrative) (Details)

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Disclosure Of Fair Value Of Assets And Liabilities (Narrative) (Details) - USD ($)
Jun. 30, 2017
Dec. 31, 2016
Disclosure Of Fair Value Of Assets And Liabilities [Abstract]    
Fair value of Company's long-term debt $ 2,934,517,000 $ 2,308,488,000
Principal balance outstanding $ 2,950,219,000 $ 2,340,009,000