Intangible Assets - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Finite-Lived Intangible Assets [Line Items]
Amortization expense for intangible assets	$ 4,696,939	$ 4,629,394	$ 4,788,174
Database [Member]
Finite-Lived Intangible Assets [Line Items]
Amount capitalize intangible asset	1,974,000	1,952,000
Amortization expense for intangible assets	1,547,000	1,907,000	2,410,000
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization expense for intangible assets	973,000	982,000	992,000
Web Site [Member]
Finite-Lived Intangible Assets [Line Items]
Amount capitalize intangible asset	2,077,000	1,855,000
Amortization expense for intangible assets	1,875,000	1,436,000	1,084,000
Acquired Below Market Lease [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization expense for intangible assets	$ 302,000	$ 304,000	$ 302,000