Intangible Assets - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Amortization expense for intangible assets	$ 1,378,486	$ 1,221,190
Database [Member]
Finite-Lived Intangible Assets [Line Items]
Amount capitalized to intangible asset	1,331,000	596,000
Amortization expense for intangible assets	612,000	482,000
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization expense for intangible assets	235,000	238,000
Website [Member]
Finite-Lived Intangible Assets [Line Items]
Amount capitalized to intangible asset	658,000	486,000
Amortization expense for intangible assets	456,000	425,000
Acquired Below Market Lease [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization expense for intangible assets	$ 75,000	$ 76,000