Segment Information - Condensed Operating Data for Segments (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Segment Reporting Information [Line Items]
Subscription revenue	$ 12,823,752	$ 11,130,778
Cost of sales of subscription revenue	2,461,571	2,185,440
Gross profit	10,362,181	8,945,338
Operating expenses:
Sales and marketing	2,667,992	2,653,014
Product development	1,005,284	862,754
General and administrative expenses	4,084,711	3,321,076
Total operating expenses	7,757,987	6,836,844
Other income (expenses):
Interest and other income	8,256	7,089
Interest expense	(21,325)	(28,213)
Total other income (expenses)	(13,069)	(21,124)
Income (loss) before income taxes and discontinued operations	2,591,125	2,087,370
Income (loss) from discontinued operations, before income taxes	0	(118,000)
Reis Services [Member]
Segment Reporting Information [Line Items]
Subscription revenue	12,824,000	11,131,000
Cost of sales of subscription revenue	2,462,000	2,186,000
Gross profit	10,362,000	8,945,000
Operating expenses:
Sales and marketing	2,668,000	2,653,000
Product development	1,005,000	863,000
General and administrative expenses	2,796,000	2,160,000
Total operating expenses	6,469,000	5,676,000
Other income (expenses):
Interest and other income	8,000	7,000
Interest expense	(21,000)	(28,000)
Total other income (expenses)	(13,000)	(21,000)
Income (loss) before income taxes and discontinued operations	3,880,000	3,248,000
Income (loss) from discontinued operations, before income taxes	0	0
Other [Member]
Segment Reporting Information [Line Items]
Subscription revenue	0	0
Cost of sales of subscription revenue	0	0
Gross profit	0	0
Operating expenses:
Sales and marketing	0	0
Product development	0	0
General and administrative expenses	1,289,000	1,161,000
Total operating expenses	1,289,000	1,161,000
Other income (expenses):
Interest and other income	0	0
Interest expense	0	0
Total other income (expenses)	0	0
Income (loss) before income taxes and discontinued operations	(1,289,000)	(1,161,000)
Income (loss) from discontinued operations, before income taxes	$ 0	$ (118,000)