Segment Information - Condensed Balance Sheet Data for Segments (Detail) - USD ($)	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 25,160,643	$ 28,657,956	$ 25,958,663	$ 17,745,077
Restricted cash and investments	212,268	212,268
Accounts receivable, net	7,117,259	13,741,169
Prepaid and other assets	1,142,216	670,339
Total current assets	33,632,386	43,281,732
Furniture, fixtures and equipment, net	2,891,722	804,427
Intangible assets, net	17,594,474	15,686,954
Deferred tax asset, net	17,001,737	18,429,737
Goodwill	54,824,648	54,824,648
Other assets	312,459	171,728
Total assets	126,257,426	133,199,226
Current liabilities:
Current portion of debt	0	0
Accrued expenses and other liabilities	3,320,998	5,898,226
Deferred revenue	22,094,152	25,291,499
Liabilities attributable to discontinued operations	0	145,737
Total current liabilities	25,415,150	31,335,462
Other long-term liabilities	1,216,001	284,316
Deferred tax liability, net	0	0
Total liabilities	26,631,151	31,619,778
Total stockholders' equity	99,626,275	101,579,448
Total liabilities and stockholders' equity	126,257,426	133,199,226
Reis Services [Member]
Current assets:
Cash and cash equivalents	22,782,000	28,465,000
Restricted cash and investments	212,000	212,000
Accounts receivable, net	7,117,000	13,741,000
Prepaid and other assets	878,000	417,000
Total current assets	30,989,000	42,835,000
Furniture, fixtures and equipment, net	2,892,000	798,000
Intangible assets, net	17,594,000	15,687,000
Deferred tax asset, net	285,000	285,000
Goodwill	57,203,000	57,203,000
Other assets	312,000	172,000
Total assets	109,275,000	116,980,000
Current liabilities:
Current portion of debt	0	0
Accrued expenses and other liabilities	3,012,000	4,502,000
Deferred revenue	22,094,000	25,291,000
Liabilities attributable to discontinued operations		0
Total current liabilities	25,106,000	29,793,000
Other long-term liabilities	1,216,000	284,000
Deferred tax liability, net	32,585,000	29,498,000
Total liabilities	58,907,000	59,575,000
Total stockholders' equity	50,368,000	57,405,000
Total liabilities and stockholders' equity	109,275,000	116,980,000
Other [Member]
Current assets:
Cash and cash equivalents	2,379,000	193,000
Restricted cash and investments	0	0
Accounts receivable, net	0	0
Prepaid and other assets	264,000	253,000
Total current assets	2,643,000	446,000
Furniture, fixtures and equipment, net	0	6,000
Intangible assets, net	0	0
Deferred tax asset, net	16,717,000	18,145,000
Goodwill	(2,378,000)	(2,378,000)
Other assets	0	0
Total assets	16,982,000	16,219,000
Current liabilities:
Current portion of debt	0	0
Accrued expenses and other liabilities	309,000	1,397,000
Deferred revenue	0	0
Liabilities attributable to discontinued operations		146,000
Total current liabilities	309,000	1,543,000
Other long-term liabilities	0	0
Deferred tax liability, net	(32,585,000)	(29,498,000)
Total liabilities	(32,276,000)	(27,955,000)
Total stockholders' equity	49,258,000	44,174,000
Total liabilities and stockholders' equity	$ 16,982,000	$ 16,219,000