Intangible Assets - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Finite-Lived Intangible Assets [Line Items]
Amortization expense for intangible assets	$ 1,153,077	$ 1,134,764
Database [Member]
Finite-Lived Intangible Assets [Line Items]
Amount capitalize intangible asset	596,000	528,000
Amortization expense for intangible assets	413,000	366,000
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization expense for intangible assets	241,000	244,000
Web Site [Member]
Finite-Lived Intangible Assets [Line Items]
Amount capitalize intangible asset	482,000	558,000
Amortization expense for intangible assets	423,000	449,000
Acquired Below Market Lease [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization expense for intangible assets	$ 76,000	$ 76,000