Segment Information - Condensed Balance Sheet Data for Segments (Detail) - USD ($)	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 18,882,602	$ 21,490,586	$ 26,554,080	$ 28,657,956
Accounts receivable, net	9,308,624	10,743,505
Prepaid and other assets	741,247	792,991
Total current assets	28,932,473	33,027,082
Furniture, fixtures and equipment, net	5,374,820	5,260,443
Intangible assets, net	19,081,875	17,922,282
Deferred tax asset, net	17,964,768	16,814,737
Goodwill	54,824,648	54,824,648
Other assets	256,628	295,349
Total assets	126,435,212	128,144,541
Current liabilities:
Current portion of debt	0	0
Accrued expenses and other liabilities	3,313,580	4,031,444
Deferred revenue	24,183,184	25,031,100
Total current liabilities	27,496,764	29,062,544
Other long-term liabilities	2,614,065	1,902,081
Deferred tax liability, net	0	0
Total liabilities	30,110,829	30,964,625
Total stockholders' equity	96,324,383	97,179,916
Total liabilities and stockholders' equity	126,435,212	128,144,541
Reis Services [Member]
Current assets:
Cash and cash equivalents	17,336,000	19,903,000
Accounts receivable, net	9,309,000	10,744,000
Prepaid and other assets	719,000	622,000
Total current assets	27,364,000	31,269,000
Furniture, fixtures and equipment, net	5,375,000	5,260,000
Intangible assets, net	19,082,000	17,922,000
Deferred tax asset, net	285,000	285,000
Goodwill	57,203,000	57,203,000
Other assets	256,000	295,000
Total assets	109,565,000	112,234,000
Current liabilities:
Current portion of debt	0	0
Accrued expenses and other liabilities	3,069,000	3,724,000
Deferred revenue	24,183,000	25,031,000
Total current liabilities	27,252,000	28,755,000
Other long-term liabilities	2,614,000	1,902,000
Deferred tax liability, net	34,118,000	32,909,000
Total liabilities	63,984,000	63,566,000
Total stockholders' equity	45,581,000	48,668,000
Total liabilities and stockholders' equity	109,565,000	112,234,000
Other [Member]
Current assets:
Cash and cash equivalents	1,547,000	1,588,000
Accounts receivable, net	0	0
Prepaid and other assets	21,000	170,000
Total current assets	1,568,000	1,758,000
Furniture, fixtures and equipment, net	0	0
Intangible assets, net	0	0
Deferred tax asset, net	17,680,000	16,530,000
Goodwill	(2,378,000)	(2,378,000)
Other assets	0	0
Total assets	16,870,000	15,910,000
Current liabilities:
Current portion of debt	0	0
Accrued expenses and other liabilities	245,000	307,000
Deferred revenue	0	0
Total current liabilities	245,000	307,000
Other long-term liabilities	0	0
Deferred tax liability, net	(34,118,000)	(32,909,000)
Total liabilities	(33,873,000)	(32,602,000)
Total stockholders' equity	50,743,000	48,512,000
Total liabilities and stockholders' equity	$ 16,870,000	$ 15,910,000