Property and Equipment (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Property, Plant and Equipment [Line Items]
Computer equipment	$ 6,645		$ 3,984
Internal-use software	4,806		2,393
Furniture and fixtures	1,873		999
Leasehold improvements	1,813		687
Total property and equipment	116,118		82,016
Less: Accumulated depreciation and amortization	(54,386)		(40,884)
Property and equipment, net	61,732	[1]	41,132	[1]	26,848	[1]
In-vehicle devices-installed
Property, Plant and Equipment [Line Items]
In-vehicle devices	96,431		71,110
In-vehicle devices-uninstalled
Property, Plant and Equipment [Line Items]
In-vehicle devices	$ 4,550		$ 2,843

[1] Long-lived tangible assets consist of property and equipment based on the country in which the assets are located and are reported at carrying value.