Revenue to External Customers Based on Billing Location of End User Customer and Long-Lived Assets by Geography (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended					12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Mar. 31, 2013
Revenue:
Revenue from United States	$ 28,148				$ 22,175
International revenue	9,165				7,795
Total revenue	37,313	33,616	32,454	29,951	29,970	133,334
Long-lived assets:
Long-lived assets in United States	38,253	37,869				38,253
International long-lived assets	7,376	7,447				7,376
Property and equipment, net	$ 45,629	$ 45,316				$ 45,629