Goodwill and Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 business	Sep. 30, 2013
Finite-Lived Intangible Assets [Line Items]
Number of businesses acquired			3
Amortization of intangibles	$ 2,505	$ 1,351	$ 5,763	$ 4,089
Software
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets useful life			3 years
Minimum | Trade Name
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets useful life			2 years
Minimum | Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets useful life			4 years
Minimum | Content
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets useful life			1 year 6 months
Minimum | Non-Compete
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets useful life			4 years
Maximum | Trade Name
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets useful life			5 years
Maximum | Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets useful life			7 years
Maximum | Content
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets useful life			4 years
Maximum | Non-Compete
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets useful life			5 years