LONG-TERM DEBT - Other Debt (Narrative) (Details) - USD ($) $ in Thousands |
Dec. 31, 2017 |
Dec. 31, 2016 |
|---|---|---|
| Debt Instrument [Line Items] | ||
| Other debt | $ 5,266,726 | $ 5,116,991 |
| Current portion of long-term debt | 573 | 6,971 |
| Other debt | ||
| Debt Instrument [Line Items] | ||
| Other debt | $ 2,393 | $ 14,798 |