Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Intangible Assets by Major Class [Line Items]
Cost	$ 23,737	$ 19,998
Accumulated Amortization	(13,009)	(9,227)
URLs purchased
Intangible Assets by Major Class [Line Items]
Cost	333	333
Other intangibles
Intangible Assets by Major Class [Line Items]
Cost	1,350	30
Customer Lists
Intangible Assets by Major Class [Line Items]
Cost	20,195	17,776
Accumulated Amortization	(11,731)	(8,646)
Noncompete Agreements
Intangible Assets by Major Class [Line Items]
Cost	1,859	1,859
Accumulated Amortization	$ (1,278)	$ (581)