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 |