LONG-TERM DEBT AND FINANCING LEASE OBLIGATIONS (Narrative) (Details) - USD ($) $ in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2017 |
Jan. 01, 2017 |
|
| Debt Instrument [Line Items] | ||
| Debt Instrument, Face Amount | $ 10.0 | |
| Line of Credit Facility, Maximum Borrowing Capacity | $ 1.0 | |
| Line of Credit [Member] | ||
| Debt Instrument [Line Items] | ||
| Debt Instrument, Basis Spread on Variable Rate | 3.25% | |
| Spirit Financing Lease [Member] | ||
| Debt Instrument [Line Items] | ||
| Long-term Debt, Weighted Average Interest Rate | 7.78% | |
| Long-term Debt [Member] | ||
| Debt Instrument [Line Items] | ||
| Long-term Debt, Weighted Average Interest Rate | 4.27% | 4.00% |
| Second Loan Agreement [Member] | ||
| Debt Instrument [Line Items] | ||
| Debt Instrument, Face Amount | $ 6.3 | |
| Debt Instrument, Basis Spread on Variable Rate | 3.25% | |
| First Loan Agreement [Member] | ||
| Debt Instrument [Line Items] | ||
| Debt Instrument, Face Amount | $ 3.7 | |
| Debt Instrument, Years until Interest Rate Change | 5 years | |
| Debt Instrument, Basis Spread on Variable Rate | 3.75% | |
| Debt Instrument Interest Rate Stated Percentage | 4.25% |