Quarterly report pursuant to Section 13 or 15(d)

LIABILITIES AND LONG-TERM DEBT LIABILITIES AND LONG-TERM DEBT - Additional Information (Details)

LIABILITIES AND LONG-TERM DEBT LIABILITIES AND LONG-TERM DEBT - Additional Information (Details)	Jul. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)
Line of Credit Facility [Line Items]
Interest rate on loan		4.24%
Unamortized debt issuance costs		$ (875,000)	$ (501,000)
Amended And Restated Credit Agreement, Third Amendment [Member] \| Minimum [Member]
Line of Credit Facility [Line Items]
Commitment fee on unused portion	0.25%
Amended And Restated Credit Agreement, Third Amendment [Member] \| Maximum [Member]
Line of Credit Facility [Line Items]
Commitment fee on unused portion	0.375%
Amended And Restated Credit Agreement, Fourth Amendment [Member]
Line of Credit Facility [Line Items]
Additional amount allowed to borrow, accordion feature	$ 50,000,000.0
Amended And Restated Credit Agreement, Fourth Amendment [Member] \| Minimum [Member]
Line of Credit Facility [Line Items]
Commitment fee on unused portion	0.20%
Consolidated fixed charge coverage ratio	1.15
Amended And Restated Credit Agreement, Fourth Amendment [Member] \| Maximum [Member]
Line of Credit Facility [Line Items]
Commitment fee on unused portion	0.30%
Consolidated leverage ratio	3.50
Various Lenders [Member] \| Revolving Credit Facility [Member] \| Amended And Restated Credit Agreement, Third Amendment [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 60,000,000.0
Debt issuance costs	300,000
Various Lenders [Member] \| Revolving Credit Facility [Member] \| Amended And Restated Credit Agreement, Fourth Amendment [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	75,000,000.0
Borrowings outstanding		20,000,000
Available remaining borrowing capacity		55,000,000
Debt issuance costs	900,000
Term Loan [Member] \| Amended And Restated Credit Agreement, Fourth Amendment [Member]
Line of Credit Facility [Line Items]
Total amount available under loan	87,500,000.0
Borrowings outstanding	60,400,000	$ 86,400,000
Term Loan [Member] \| Acquisition Term Loan [Member]
Line of Credit Facility [Line Items]
Borrowings outstanding	70,000,000
Term Loan [Member] \| Multiple Advance Term Loan [Member]
Line of Credit Facility [Line Items]
Borrowings outstanding	$ 0
London Interbank Offered Rate (LIBOR) [Member] \| Amended And Restated Credit Agreement, Third Amendment [Member] \| Minimum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	2.00%
London Interbank Offered Rate (LIBOR) [Member] \| Amended And Restated Credit Agreement, Third Amendment [Member] \| Maximum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	3.00%
London Interbank Offered Rate (LIBOR) [Member] \| Amended And Restated Credit Agreement, Fourth Amendment [Member] \| Minimum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.25%
London Interbank Offered Rate (LIBOR) [Member] \| Amended And Restated Credit Agreement, Fourth Amendment [Member] \| Maximum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	2.25%
Base Rate [Member] \| Amended And Restated Credit Agreement, Third Amendment [Member] \| Minimum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.00%
Base Rate [Member] \| Amended And Restated Credit Agreement, Third Amendment [Member] \| Maximum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	2.00%
Base Rate [Member] \| Amended And Restated Credit Agreement, Fourth Amendment [Member] \| Minimum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.25%
Base Rate [Member] \| Amended And Restated Credit Agreement, Fourth Amendment [Member] \| Maximum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.25%