Stock-Based Compensation - Summary of Stock Option and Restricted Stock Units Award Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2015	Dec. 31, 2014
Shares Available for Grant
Beginning balance		1,825,112
Increase in shares authorized		3,255,200
Options granted	0	(328,680)
Options canceled or expired		49,829
RSUs granted		(3,155,953)
RSUs released		(1,687,983)
RSUs canceled or expired		1,117,472
Ending balance		2,762,980	1,825,112
Number of Shares
Beginning balance		9,494,763
Options granted	0	328,680
Options exercised		(1,034,605)
Options canceled or expired		(49,829)
Ending balance		8,739,009	9,494,763
Vested and expected to vest at the end of period		8,350,252
Vested and exercisable at the end of period		6,668,290
Weighted Average Exercise Price
Beginning balance		$ 7.00
Options granted		10.05
Options exercised		3.51
Options canceled or expired		8.04
Ending balance		7.52	$ 7.00
Vested and expected to vest at the end of period		7.27
Vested and exercisable at the end of period		$ 5.82
Weighted Average Remaining Contractual Term (Years) / Aggregate Intrinsic Value
Weighted Average Remaining Contractual Term (Years)		6 years 1 month 13 days	6 years 6 months 26 days
Vested and expected to vest at the end of period		6 years 11 days
Vested and exercisable at the end of period		5 years 5 months 16 days
Aggregate Intrinsic Value, Beginning balance		$ 107,913
Options exercised		9,438
Aggregate Intrinsic Value, Ending balance		31,768	$ 107,913
Vested and expected to vest at the end of period		31,409
Vested and exercisable at the end of period		$ 30,100
Restricted Stock Units, Number of Shares
Beginning balance		6,809,415
RSUs granted		3,155,953
RSUs released		(1,687,983)
RSUs canceled or expired		(1,117,472)
Ending balance		7,159,913	6,809,415
Weighted Average Grant Date Fair Value
Beginning Balance		$ 12.66
RSUs granted		13.48
RSUs released		11.75
RSUs canceled or expired		12.83
Ending balance		$ 13.14	$ 12.66