Schedule of Convertible Preferred Stock - Summary of Preferred Stock (Detail) (USD $)	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Temporary Equity [Line Items]
Convertible preferred stock, shares authorized	5,000,000	5,000,000	135,816,462
Convertible preferred stock, shares outstanding	0		120,648,174
Convertible preferred stock, Carrying Value			$ 57,497,000
Series A Preferred Stock [Member]
Temporary Equity [Line Items]
Convertible preferred stock, shares authorized			22,000,000
Convertible preferred stock, shares outstanding			22,000,000
Convertible preferred stock, liquidation preference per share			$ 0.45
Convertible preferred stock, Carrying Value			9,900,000
Series B Preferred Stock [Member]
Temporary Equity [Line Items]
Convertible preferred stock, shares authorized			46,425,950
Convertible preferred stock, shares outstanding			44,425,953
Convertible preferred stock, liquidation preference per share			$ 0.45
Convertible preferred stock, Carrying Value			18,631,000
Series C Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Convertible preferred stock, shares authorized			36,444,444
Convertible preferred stock, shares outstanding			36,444,444
Convertible preferred stock, liquidation preference per share			$ 0.56
Convertible preferred stock, Carrying Value			19,301,000
Series D-1 Preferred [Member]
Temporary Equity [Line Items]
Convertible preferred stock, shares authorized			17,777,777
Convertible preferred stock, shares outstanding			17,777,777
Convertible preferred stock, liquidation preference per share			$ 0.56
Convertible preferred stock, Carrying Value			$ 9,665,000
Series D-2 Preferred [Member]
Temporary Equity [Line Items]
Convertible preferred stock, shares authorized			13,168,291
Convertible preferred stock, liquidation preference per share			$ 0.76