SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, Stock-Based Compensation (Details)	3 Months Ended		9 Months Ended			12 Months Ended
	Sep. 30, 2018 USD ($) $ / shares shares	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) Plan $ / shares shares		Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($) $ / shares shares	Sep. 28, 2018 $ / shares
Share-Based Compensation [Abstract]
Number of stock based compensation plans | Plan			1
Additional Disclosures [Abstract]
Proceeds from stock option exercises			$ 2,570,830	[1]	$ 258,250
Closing price of common stock (in dollars per share) | $ / shares							$ 58.49
General and Administrative [Member]
Share Based Compensation Expense [Abstract]
Stock-based compensation expense	$ 64,000	$ 33,000	$ 160,000		100,000
Stock Options [Member]
Weighted Average Grant Date Fair Value [Abstract]
Weighted average grant date fair value (in dollars per share) | $ / shares			$ 18.00
Assumptions Used in Valuation of Stock Options Granted [Abstract]
Risk-free interest rate, minimum			2.62%
Risk-free interest rate, maximum			2.81%
Expected term of option			6 years 3 months
Expected stock price volatility, minimum			39.60%
Expected stock price volatility, maximum			39.70%
Expected dividend yield			0.00%
Stock Options Activity [Roll Forward]
Outstanding, beginning of period (in shares) | shares			232,000
Grants (in shares) | shares			31,500
Exercised (in shares) | shares			(138,000)
Forfeitures or expirations (in shares) | shares			0
Outstanding, end of period (in shares) | shares	125,500		125,500			232,000
Exercisable, end of period (in shares) | shares	86,500		86,500
Weighted Average Exercise Price [Roll Forward]
Outstanding, beginning of period (in dollars per share) | $ / shares			$ 21.56
Grants (in dollars per share) | $ / shares			41.79
Exercised (in dollars per share) | $ / shares			18.63
Forfeitures or expirations (in dollars per share) | $ / shares			0
Outstanding, end of period (in dollars per share) | $ / shares	$ 29.86		29.86			$ 21.56
Exercisable, end of period (in dollars per share) | $ / shares	$ 24.84		$ 24.84
Weighted Average Remaining Contractual Term [Roll Forward]
Outstanding			5 years 1 month 28 days			2 years 6 months 7 days
Grants			0 years
Exercised			0 years
Forfeitures or expirations			0 years
Exercisable			3 years 5 months 19 days
Aggregate Intrinsic Value [Roll Forward]
Outstanding, beginning of period			$ 5,050,990
Grants			0
Exercised			3,720,149
Forfeitures or expirations			0
Outstanding, end of period	$ 3,593,430		3,593,430			$ 5,050,990
Exercisable, end of period	2,910,945		2,910,945
Additional Disclosures [Abstract]
Proceeds from stock option exercises			2,600,000		$ 258,000
Unrecognized compensation cost	$ 548,000		$ 548,000
Recognized compensation period			3 years 2 months 1 day

[1] As of January 1, 2018, the Company adopted the requirements of ASC 606 using the modified retrospective adoption method, and as a result, there is a lack of comparability of certain amounts to the prior periods presented. 3-Summary of Significant Accounting Policies for additional discussion.