LONG-TERM DEBT - Additional information (Details) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2013	Dec. 31, 2016	Apr. 26, 2016	Feb. 19, 2015
Long-term Debt and Capital Lease Obligations, Including Current Maturities [Abstract]
Long-term Debt	$ 325,124,000		$ 281,673,000
2017	21,524,000
2018	(21,622,000)
2019	(18,261,000)
2020	(11,801,000)
2021	(7,148,000)
Thereafter	(280,762,000)
Loan amount attributable to interest	(767,000)
Total	325,124,000		281,673,000
Long-term debt and capital Lease Obligations, Total	360,351,000
Senior Debt
Long-term Debt and Capital Lease Obligations, Including Current Maturities [Abstract]
2017	2,895,000
2018	2,895,000
2019	2,895,000
2020	2,895,000
2021	2,895,000
Thereafter	274,301,000
Long-term Debt	288,776,000
Total	$ 288,776,000
Equipment term loans
Loan amount				$ 8,800,000	$ 7,800,000
Interest rate (as a percent)	3.25%
Long-term Debt and Capital Lease Obligations, Including Current Maturities [Abstract]
2017	$ 16,294,000
2018	16,834,000
2019	14,214,000
2020	8,710,000
2021	4,134,000
Thereafter	6,284,000
Long-term Debt	66,470,000
Total	66,470,000
Capital leases
Long-term Debt and Capital Lease Obligations, Including Current Maturities [Abstract]
2017	2,335,000
2018	1,893,000
2019	1,152,000
2020	196,000
2021	119,000
Thereafter	177,000
Total minimum lease payments	5,872,000
Loan amount attributable to interest	(767,000)
Total (Present value of minimum lease payments on capital leases)	5,105,000
Less current portion	(2,331,000)
Long-term capital leases	2,774,000
Senior subordinated secured debt | Main Street Capital Corporation
Loan amount		$ 20,000,000
Interest rate (as a percent)		12.00%
Paid-in-kind interest (as a percent)		2.50%
Accrued, Paid-in-kind interest added to principal balance	100,000		500,000
Accrued, Paid-in-kind, interest			100,000
Senior subordinated secured debt | Prudential Capital Partners
Loan amount		$ 20,000,000
Interest rate (as a percent)		12.00%
Paid-in-kind interest (as a percent)		2.50%
Accrued, Paid-in-kind interest added to principal balance	$ 100,000		500,000
Accrued, Paid-in-kind, interest			$ 100,000
Subordinated Debt.
Make-whole payment	5.00%
Subordinated Debt. | LST Seller notes
Loan amount	$ 22.0
Interest rate (as a percent)	10.00%
Subordinated Debt. | DTR Seller notes
Loan amount	$ 1.0
Interest rate (as a percent)	5.00%
Subordinated Debt. | BHE Seller notes
Loan amount	$ 2.0
Interest rate (as a percent)	7.00%