Common Stock - Reserved Shares of Common Stock (Detail) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Class of Stock [Line Items]
Reserved shares of Common Stock	11,304	10,294
Shares Available for Future Issuance under ESPP [Member]
Class of Stock [Line Items]
Reserved shares of Common Stock	1,005	854
RSUs [Member]
Class of Stock [Line Items]
Reserved shares of Common Stock	769	0
Options Outstanding [Member]
Class of Stock [Line Items]
Reserved shares of Common Stock	6,376	4,855
Options Available for Future Grant [Member]
Class of Stock [Line Items]
Reserved shares of Common Stock	3,154	4,585