Segment Information - Condensed Balance Sheet Data for Segments (Detail) - USD ($)	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 21,490,586	$ 28,657,956	$ 17,745,077	$ 10,559,899
Restricted cash and investments	0	212,268
Accounts receivable, net	10,743,505	13,741,169
Prepaid and other assets	792,991	670,339
Total current assets	33,027,082	43,281,732
Furniture, fixtures and equipment, net	5,260,443	804,427
Intangible assets, net	17,922,282	15,686,954
Deferred tax asset, net	16,814,737	18,429,737
Goodwill	54,824,648	54,824,648
Other assets	295,349	171,728
Total assets	128,144,541	133,199,226
Current liabilities:
Current portion of debt	0	0
Accrued expenses and other liabilities	4,031,444	5,898,226
Deferred revenue	25,031,100	25,291,499
Liabilities attributable to discontinued operations	0	145,737
Total current liabilities	29,062,544	31,335,462
Other long-term liabilities	1,902,081	284,316
Deferred tax liability, net	0	0
Total liabilities	30,964,625	31,619,778
Total stockholders' equity	97,179,916	101,579,448	$ 96,113,406	$ 92,870,959
Total liabilities and stockholders' equity	128,144,541	133,199,226
Reis Services [Member]
Current assets:
Cash and cash equivalents	19,903,000	28,465,000
Restricted cash and investments		212,000
Accounts receivable, net	10,744,000	13,741,000
Prepaid and other assets	622,000	417,000
Total current assets	31,269,000	42,835,000
Furniture, fixtures and equipment, net	5,260,000	798,000
Intangible assets, net	17,922,000	15,687,000
Deferred tax asset, net	285,000	285,000
Goodwill	57,203,000	57,203,000
Other assets	295,000	172,000
Total assets	112,234,000	116,980,000
Current liabilities:
Current portion of debt	0	0
Accrued expenses and other liabilities	3,724,000	4,502,000
Deferred revenue	25,031,000	25,291,000
Liabilities attributable to discontinued operations		0
Total current liabilities	28,755,000	29,793,000
Other long-term liabilities	1,902,000	284,000
Deferred tax liability, net	32,909,000	29,498,000
Total liabilities	63,566,000	59,575,000
Total stockholders' equity	48,668,000	57,405,000
Total liabilities and stockholders' equity	112,234,000	116,980,000
Other [Member]
Current assets:
Cash and cash equivalents	1,588,000	193,000
Restricted cash and investments		0
Accounts receivable, net	0	0
Prepaid and other assets	170,000	253,000
Total current assets	1,758,000	446,000
Furniture, fixtures and equipment, net	0	6,000
Intangible assets, net	0	0
Deferred tax asset, net	16,530,000	18,145,000
Goodwill	(2,378,000)	(2,378,000)
Other assets	0	0
Total assets	15,910,000	16,219,000
Current liabilities:
Current portion of debt	0	0
Accrued expenses and other liabilities	307,000	1,397,000
Deferred revenue	0	0
Liabilities attributable to discontinued operations		146,000
Total current liabilities	307,000	1,543,000
Other long-term liabilities	0	0
Deferred tax liability, net	(32,909,000)	(29,498,000)
Total liabilities	(32,602,000)	(27,955,000)
Total stockholders' equity	48,512,000	44,174,000
Total liabilities and stockholders' equity	$ 15,910,000	$ 16,219,000