REVENUE RECOGNITION - Impact of Adoption on Financial Statements (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
Income Statement [Abstract]
Revenues	$ 37,987	$ 38,917	$ 41,595	$ 43,071	$ 50,936	$ 52,424	$ 52,400	$ 52,190	$ 161,570	$ 207,950	$ 226,970
Operating Expenses	35,615	37,085	39,686	40,861	48,898	49,886	48,398	47,895	153,247
Gain (Loss) on Disposition of Business									3,369	6,699	0
Operating income (loss)	2,306	1,467	1,070	6,849	12,030	2,538	4,002	4,295	11,692	22,865	3,391
Net income (loss)	$ 2,946	$ 930	$ (205)	$ 3,503	$ 11,758	$ 1,058	$ 1,822	$ 1,340	$ 7,174	$ 15,978	$ (5,398)
Basic earnings (loss) per share (in dollars per share)	$ 0.06	$ 0.02	$ 0.00	$ 0.07	$ 0.24	$ 0.02	$ 0.04	$ 0.03	$ 0.15	$ 0.33	$ (0.11)
Diluted earnings (loss) per share (in dollars per share)	$ 0.06	$ 0.02	$ 0.00	$ 0.07	$ 0.24	$ 0.02	$ 0.04	$ 0.03	$ 0.14	$ 0.33	$ (0.11)
Statement of Financial Position [Abstract]
Capitalized Contract Cost, Net	$ 7,939				$ 0				$ 7,939	$ 0
Assets	258,385				295,718				258,385	295,718	$ 310,095
Deferred Revenue	54,723				83,646				54,723	83,646		$ 83,646
Deferred income taxes	10,444				8,245				10,444	8,245
Liabilities	113,030				163,077				113,030	163,077
Accumulated earnings	71,435				59,776				71,435	59,776
Stockholders' Equity Attributable to Parent	145,355				132,641				145,355	132,641
Liabilities and Equity	258,385				$ 295,718				258,385	295,718
Statement of Cash Flows [Abstract]
Deferred income taxes									2,699	212	(3,268)
Gain (Loss) on Disposition Cost From Sale									3,369	6,699	(639)
Increase (Decrease) in Contract with Customer, Asset									(3,236)	0	0
Deferred revenue									(18,866)	712	2,370
Net Cash Provided by (Used in) Operating Activities									14,918	$ 34,409	$ 44,997
Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Income Statement [Abstract]
Revenues									113
Operating Expenses									(2,882)
Gain (Loss) on Disposition of Business									(1,199)
Operating income (loss)									1,796
Net income (loss)									$ 1,347
Basic earnings (loss) per share (in dollars per share)									$ 0.03
Diluted earnings (loss) per share (in dollars per share)									$ 0.02
Statement of Financial Position [Abstract]
Capitalized Contract Cost, Net	7,939								$ 7,939
Assets	7,939								7,939
Deferred Revenue	113								113
Deferred income taxes	1,994								1,994
Liabilities	2,107								2,107
Accumulated earnings	5,832								5,832
Stockholders' Equity Attributable to Parent	5,832								5,832
Liabilities and Equity	7,939								7,939
Statement of Cash Flows [Abstract]
Deferred income taxes									803
Gain (Loss) on Disposition Cost From Sale									1,199
Increase (Decrease) in Contract with Customer, Asset									(3,236)
Deferred revenue									(113)
Net Cash Provided by (Used in) Operating Activities									0
Accounting Standards Update 2014-09 [Member] | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Income Statement [Abstract]
Revenues									161,457
Operating Expenses									156,129
Gain (Loss) on Disposition of Business									4,568
Operating income (loss)									9,896
Net income (loss)									$ 5,827
Basic earnings (loss) per share (in dollars per share)									$ 0.12
Diluted earnings (loss) per share (in dollars per share)									$ 0.12
Statement of Financial Position [Abstract]
Capitalized Contract Cost, Net	0								$ 0
Assets	250,446								250,446
Deferred Revenue	54,610								54,610
Deferred income taxes	8,450								8,450
Liabilities	110,923								110,923
Accumulated earnings	65,603								65,603
Stockholders' Equity Attributable to Parent	139,523								139,523
Liabilities and Equity	250,446								250,446
Statement of Cash Flows [Abstract]
Deferred income taxes									1,896
Gain (Loss) on Disposition Cost From Sale									(4,568)
Increase (Decrease) in Contract with Customer, Asset									0
Deferred revenue									(18,753)
Net Cash Provided by (Used in) Operating Activities									14,918
Accounting Standards Update 2014-09 [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Income Statement [Abstract]
Revenues									200
Statement of Financial Position [Abstract]
Capitalized Contract Cost, Net	6,100								6,100
Accumulated earnings	$ 4,500								$ 4,500			$ 4,500