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LONG TERM DEBT AND CAPITAL LEASES - Credit Facility (Details)	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Line of Credit Facility [Line Items]
Debt redemption price		101.938%
Revolving Credit Facility due October 2021; bearing interest at LIBOR plus 3.00%
Line of Credit Facility [Line Items]
Basis spread on variable rate		3.00%
Secured Debt | Term Loan B Facility
Line of Credit Facility [Line Items]
Principal amount		$ 350,000,000
Facility term		7 years
Net leverage ratio		3.75
Interest rate	2.50%
Secured Debt | Term Loan B Facility | LIBOR
Line of Credit Facility [Line Items]
Basis spread on variable rate		2.75%
Secured Debt | Term Loan B Facility | LIBOR | Maximum
Line of Credit Facility [Line Items]
Basis spread on variable rate		3.00%
Secured Debt | Term Loan B Facility | LIBOR Floor | Minimum
Line of Credit Facility [Line Items]
Basis spread on variable rate		1.00%
Secured Debt | Term Loan Facility B, Repricing Amendment
Line of Credit Facility [Line Items]
Net leverage ratio	3.75
Secured Debt | Term Loan Facility B, Repricing Amendment | LIBOR
Line of Credit Facility [Line Items]
Interest rate	2.75%
Secured Debt | Term Loan Facility B, Repricing Amendment | LIBOR | Debt Instrument, Covenant Compliance, Consolidated Net Leverage Ratio
Line of Credit Facility [Line Items]
Interest rate	2.50%
Secured Debt | Term Loan Facility B, Repricing Amendment | LIBOR Floor
Line of Credit Facility [Line Items]
Interest rate	1.00%
Secured Debt | Term Loan Facility B, Repricing Amendment | LIBOR Floor | Debt Instrument, Covenant Compliance, Consolidated Net Leverage Ratio
Line of Credit Facility [Line Items]
Interest rate	1.00%
Secured Debt | Term Loan Facility B, Repricing Amendment | Base Rate
Line of Credit Facility [Line Items]
Decrease in basis points	0.25%
Interest rate	1.75%
Secured Debt | Term Loan Facility B, Repricing Amendment | Base Rate | Debt Instrument, Covenant Compliance, Consolidated Net Leverage Ratio
Line of Credit Facility [Line Items]
Interest rate	1.50%
Line of Credit | Revolving Credit Facility due October 2021; bearing interest at LIBOR plus 3.00% | Revolving Credit Facility
Line of Credit Facility [Line Items]
Credit facility maximum		$ 160,000,000
Facility term		5 years
Remaining capacity	$ 101,457,000
Line of Credit | Revolving Credit Facility due October 2021; bearing interest at LIBOR plus 3.00% | Revolving Credit Facility | Minimum
Line of Credit Facility [Line Items]
Debt instrument interest rate		2.50%
Line of Credit | Revolving Credit Facility due October 2021; bearing interest at LIBOR plus 3.00% | Revolving Credit Facility | Maximum
Line of Credit Facility [Line Items]
Debt instrument interest rate		3.25%
Line of Credit | Revolving Credit Facility due October 2021; bearing interest at LIBOR plus 3.00% | Letter of Credit
Line of Credit Facility [Line Items]
Outstanding irrevocable letters of credit totaling	$ 22,543,000
Senior Subordinated Notes, Due February 2019; bore interest at 7.75%
Line of Credit Facility [Line Items]
Debt instrument interest rate		7.75%
Revolving Credit Facility
Line of Credit Facility [Line Items]
Additional revolver capacity		$ 100,000,000
Interest rate	2.75%

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- Definition

Amount of additional optional borrowing capacity under the credit facility.

+ References

No definition available.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph e
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Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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