Income Taxes - Temporary Differences and Carry Forwards Which Give Rise to Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets
Net operating loss carryforwards	$ 22,950	$ 20,218	$ 17,610
Deferred revenue and setup charges	1,062	1,299	3,171
Operating lease liabilities	1,904	2,266	0
Property and equipment	0	512	0
Leases	400	0	1
Credits	300	300	287
Equity compensation	1,654	1,119	952
Bad debt reserve	191	18	409
Intangibles	1,038	804	0
Interest expense carryforward IRC Sec. 163(j)	1,164	2,782	2,253
Other	857	257	582
Gross deferred tax assets	31,520	29,575	25,265
Deferred tax liabilities
Property and equipment	(616)	0	(3,089)
Goodwill	(3,042)	(2,494)	(1,953)
Intangibles	0	(591)	(11,910)
Operating lease right-of-use assets	(1,056)	(1,261)	0
Prepaid commissions	(774)	(1,007)	(956)
Other	(218)	(224)	(93)
Gross deferred tax liabilities	(5,706)	(5,577)	(18,001)
Net deferred tax asset	25,814	23,998	7,264
Valuation allowance	26,624	24,747	8,361
Net deferred tax liability	$ (810)	$ (749)	$ (1,097)