SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, Stock-Based Compensation (Details)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017 USD ($) $ / shares shares	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) Plan $ / shares shares	Jun. 30, 2016 USD ($) shares	Dec. 31, 2016 USD ($) $ / shares shares
Share-based Compensation [Abstract]
Number of stock based compensation plans | Plan			1
Additional Disclosures [Abstract]
Proceeds from stock option exercises			$ 258,250	$ 177,250
Closing price of common stock (in dollars per share) | $ / shares	$ 49.51		$ 49.51
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 33,000	$ 34,000	$ 67,000	$ 67,000
Stock Options [Member]
Stock Options Activity [Roll Forward]
Outstanding, beginning of period (in shares) | shares			297,000
Grants (in shares) | shares			0	0
Exercised (in shares) | shares			(20,000)
Forfeitures or expirations (in shares) | shares			0
Outstanding, end of period (in shares) | shares	277,000		277,000		297,000
Exercisable, end of period (in shares) | shares	238,250		238,250
Weighted Average Exercise Price [Roll Forward]
Outstanding, beginning of period (in dollars per share) | $ / shares			$ 20.14
Grants (in dollars per share) | $ / shares			0
Exercised (in dollars per share) | $ / shares			12.91
Forfeitures or expirations (in dollars per share) | $ / shares			0
Outstanding, end of period (in dollars per share) | $ / shares	$ 20.66		20.66		$ 20.14
Exercisable, end of period (in dollars per share) | $ / shares	$ 18.92		$ 18.92
Weighted Average Remaining Contractual Term [Roll Forward]
Outstanding			2 years 8 months 26 days		3 years 1 month 6 days
Grants			0 years
Exercised			0 years
Forfeitures or expirations			0 years
Exercisable			2 years 4 months 20 days
Aggregate Intrinsic Value [Roll Forward]
Outstanding, beginning of period			$ 10,561,380
Grants			0
Exercised			0
Forfeitures or expirations			0
Outstanding, end of period	$ 7,991,000		7,991,000		$ 10,561,380
Exercisable, end of period	7,288,450		7,288,450
Additional Disclosures [Abstract]
Proceeds from stock option exercises			258,250	$ 177,250
Unrecognized compensation cost	$ 201,000		$ 201,000
Recognized compensation period			1 year 9 months 18 days