Intangible Assets - Intangible Assets (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Customer relationships, Gross Carrying Amount	$ 60,070	$ 59,994
Acquired technology, Gross Carrying Amount	54,365	54,424
Non-compete agreements, Gross Carrying Amount	12,972	12,946
Indefinite-lived intangible assets:
Gross Carrying Amount	169,661	169,478
Accumulated Amortization	(103,974)	(100,214)
Net Balance	65,687	69,264
Trademarks [Member]
Indefinite-lived intangible assets:
Net Balance, Indefinite-Lived Intangible Assets	37,854	37,714
Net Balance, Indefinite-Lived Intangible Assets	37,854	37,714
Domain Names [Member]
Indefinite-lived intangible assets:
Net Balance, Indefinite-Lived Intangible Assets	4,400	4,400
Net Balance, Indefinite-Lived Intangible Assets	$ 4,400	4,400
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Weighted-Average Amortization Period (Years)	10 years
Indefinite-lived intangible assets:
Accumulated Amortization	$ (49,825)	(48,767)
Net Balance, Finite-Lived Intangible Assets	$ 10,245	11,227
Acquired Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Weighted-Average Amortization Period (Years)	11 years
Indefinite-lived intangible assets:
Accumulated Amortization	$ (41,858)	(39,336)
Net Balance, Finite-Lived Intangible Assets	$ 12,507	15,088
Non-compete Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Weighted-Average Amortization Period (Years)	4 years
Indefinite-lived intangible assets:
Accumulated Amortization	$ (12,291)	(12,111)
Net Balance, Finite-Lived Intangible Assets	$ 681	$ 835