Segment Information - Condensed Operating Data for Segments (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting Information [Line Items]
Subscription revenue	$ 11,614,670	$ 13,416,035	$ 24,438,422	$ 24,546,813
Cost of sales of subscription revenue	2,494,753	2,134,526	4,956,324	4,319,966
Gross profit	9,119,917	11,281,509	19,482,098	20,226,847
Operating expenses:
Sales and marketing	3,024,664	3,460,773	5,692,656	6,113,787
Product development	1,015,370	889,687	2,020,654	1,752,441
General and administrative expenses	3,536,741	3,382,146	7,621,452	6,703,222
Total operating expenses	7,576,775	7,732,606	15,334,762	14,569,450
Other income (expenses):
Interest and other income	5,910	8,505	14,166	15,594
Interest expense	(28,216)	(28,283)	(49,541)	(56,496)
Total other income (expenses)	(22,306)	(19,778)	(35,375)	(40,902)
Income (loss) before income taxes and discontinued operations	1,520,836	3,529,125	4,111,961	5,616,495
Income from discontinued operations, before income taxes	0	1,893,000	0	1,775,000
Reis Services [Member]
Segment Reporting Information [Line Items]
Subscription revenue	11,614,000	13,416,000	24,438,000	24,547,000
Cost of sales of subscription revenue	2,494,000	2,134,000	4,956,000	4,320,000
Gross profit	9,120,000	11,282,000	19,482,000	20,227,000
Operating expenses:
Sales and marketing	3,025,000	3,461,000	5,693,000	6,114,000
Product development	1,016,000	889,000	2,021,000	1,752,000
General and administrative expenses	2,535,000	2,224,000	5,331,000	4,384,000
Total operating expenses	6,576,000	6,574,000	13,045,000	12,250,000
Other income (expenses):
Interest and other income	6,000	8,000	14,000	15,000
Interest expense	(28,000)	(28,000)	(49,000)	(56,000)
Total other income (expenses)	(22,000)	(20,000)	(35,000)	(41,000)
Income (loss) before income taxes and discontinued operations	2,522,000	4,688,000	6,402,000	7,936,000
Income from discontinued operations, before income taxes	0	0	0	0
Other [Member]
Segment Reporting Information [Line Items]
Subscription revenue	0	0	0	0
Cost of sales of subscription revenue	0	0	0	0
Gross profit	0	0	0	0
Operating expenses:
Sales and marketing	0	0	0	0
Product development	0	0	0	0
General and administrative expenses	1,001,000	1,159,000	2,290,000	2,320,000
Total operating expenses	1,001,000	1,159,000	2,290,000	2,320,000
Other income (expenses):
Interest and other income	0	0	0	0
Interest expense	0	0	0	0
Total other income (expenses)	0	0	0	0
Income (loss) before income taxes and discontinued operations	(1,001,000)	(1,159,000)	(2,290,000)	(2,320,000)
Income from discontinued operations, before income taxes	$ 0	$ 1,893,000	$ 0	$ 1,775,000