Segment Information - Condensed Operating Data for Segments (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue:
Subscription revenue	$ 11,520,201	$ 11,429,089	$ 23,077,356	$ 23,008,451
Other revenue	463,693	280,131	686,193	826,723
Total revenue	11,983,894	11,709,220	23,763,549	23,835,174
Cost of sales	3,313,992	3,216,079	6,691,355	6,582,430
Gross profit	8,669,902	8,493,141	17,072,194	17,252,744
Operating expenses:
Sales and marketing	3,234,762	3,105,068	6,233,321	6,433,116
Product development	1,295,001	1,105,627	2,584,043	2,272,298
General and administrative expenses	4,692,179	3,712,557	9,171,703	7,833,041
Total operating expenses	9,221,942	7,923,252	17,989,067	16,538,455
Other income (expenses):
Interest and other income	(279)	1,126	687	1,702
Interest expense	(27,684)	(32,372)	(59,918)	(64,606)
Total other income (expenses)	(27,963)	(31,246)	(59,231)	(62,904)
(Loss) income before income taxes	(580,003)	538,643	(976,104)	651,385
Operating Segments [Member] | Reis Services [Member]
Revenue:
Subscription revenue	11,521,000	11,429,000	23,078,000	23,008,000
Other revenue	463,000	280,000	686,000	827,000
Total revenue	11,984,000	11,709,000	23,764,000	23,835,000
Cost of sales	3,314,000	3,216,000	6,692,000	6,582,000
Gross profit	8,670,000	8,493,000	17,072,000	17,253,000
Operating expenses:
Sales and marketing	3,234,000	3,105,000	6,233,000	6,433,000
Product development	1,295,000	1,106,000	2,584,000	2,273,000
General and administrative expenses	2,865,000	2,728,000	5,906,000	5,612,000
Total operating expenses	7,394,000	6,939,000	14,723,000	14,318,000
Other income (expenses):
Interest and other income	(1,000)		(1,000)	1,000
Interest expense	(28,000)	(32,000)	(60,000)	(65,000)
Total other income (expenses)	(29,000)	(32,000)	(61,000)	(64,000)
(Loss) income before income taxes	1,247,000	1,522,000	2,288,000	2,871,000
Other [Member]
Operating expenses:
General and administrative expenses	1,828,000	985,000	3,266,000	2,221,000
Total operating expenses	1,828,000	985,000	3,266,000	2,221,000
Other income (expenses):
Interest and other income	1,000	1,000	2,000	1,000
Total other income (expenses)	1,000	1,000	2,000	1,000
(Loss) income before income taxes	$ (1,827,000)	$ (984,000)	$ (3,264,000)	$ (2,220,000)