Geographic Area Data Summarizes Subscription Revenue and Long-lived Tangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Subscription revenue	$ 177,350	[1]	$ 127,451	[1]	$ 92,317	[1]
Property and equipment, net	61,732	[2]	41,132	[2]	26,848	[2]
UNITED STATES
Subscription revenue	155,554	[1]	111,386	[1]	78,776	[1]
Property and equipment, net	51,085	[2]	34,232	[2]	21,607	[2]
UNITED KINGDOM
Subscription revenue	11,423	[1]	8,944	[1]	8,146	[1]
Property and equipment, net	4,493	[2]	3,407	[2]	2,304	[2]
IRELAND
Subscription revenue	3,880	[1]	3,742	[1]	4,474	[1]
Property and equipment, net	6,082	[2]	3,493	[2]	2,937	[2]
All Other Countries
Subscription revenue	6,493	[1]	3,379	[1]	921	[1]
Property and equipment, net	$ 72	[2]

[1] Subscription revenue represents sales to external customers based on the location of the customer.

[2] 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.