Intangible Assets - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Finite-Lived Intangible Assets [Line Items]
Amortization expense for intangible assets	$ 1,498,000	$ 1,289,000	$ 4,310,343	$ 3,790,118
Database [Member]
Finite-Lived Intangible Assets [Line Items]
Amount capitalized to intangible asset	1,338,000	887,000	4,059,000	2,201,000
Amortization expense for intangible assets	761,000	541,000	2,031,000	1,530,000
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization expense for intangible assets	233,000	237,000	702,000	713,000
Website [Member]
Finite-Lived Intangible Assets [Line Items]
Amount capitalized to intangible asset	768,000	1,243,000	2,158,000	2,254,000
Amortization expense for intangible assets	475,000	436,000	1,397,000	1,320,000
Acquired Below Market Lease [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization expense for intangible assets	$ 29,000	$ 75,000	$ 180,000	$ 227,000