Common Stock and Redeemable and Convertible Preferred Stock - Summary of Redeemable and Convertible Preferred Stock (Details) - USD ($) $ in Thousands	Dec. 31, 2014	Mar. 28, 2014
Class Of Stock [Line Items]
Convertible preferred stock, authorized	105,140,116
Convertible preferred stock, issued	32,972,793
Convertible preferred stock, outstanding	103,362,446
Convertible preferred stock, net carrying value	$ 82,881
Preferred stock, aggregate liquidation preference	$ 130,043
Series A Convertible Preferred Stock [Member]
Class Of Stock [Line Items]
Convertible preferred stock, authorized	68,000,000
Convertible preferred stock, issued	16,765,775
Convertible preferred stock, outstanding	67,063,127
Convertible preferred stock, net carrying value	$ 23,324
Preferred stock, aggregate liquidation preference	$ 67,063
Series B Convertible Preferred Stock [Member]
Class Of Stock [Line Items]
Convertible preferred stock, authorized	17,000,000
Convertible preferred stock, issued	4,222,670
Convertible preferred stock, outstanding	16,890,690
Convertible preferred stock, net carrying value	$ 15,202
Preferred stock, aggregate liquidation preference	$ 16,891
Series C Convertible Preferred Stock [Member]
Class Of Stock [Line Items]
Convertible preferred stock, authorized	9,586,346
Convertible preferred stock, issued	2,396,584
Convertible preferred stock, outstanding	9,586,346
Convertible preferred stock, net carrying value	$ 10,257
Preferred stock, aggregate liquidation preference	$ 9,586
Series D Redeemable Convertible Preferred Stock [Member]
Class Of Stock [Line Items]
Convertible preferred stock, authorized	10,553,770
Convertible preferred stock, issued	9,587,764	9,587,764
Convertible preferred stock, outstanding	9,822,283
Convertible preferred stock, net carrying value	$ 34,098
Preferred stock, aggregate liquidation preference	$ 36,503