Share Based Awards - Options activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Options Activity Rollforward
Number of Shares Available for Issuance, Beginning Balance	7,392,158	2,085,338	574,597
Options Outstanding, Number, Beginning Balance	16,435,568	13,330,882	10,950,917
Number of Shares Available for Issuance, Authorized	5,418,242	9,913,915	4,478,151
Number of Shares Available for Issuance, Granted	(1,089,100)	(5,373,131)	(4,891,242)
Options Outstanding, Shares Granted	1,089,100
Number of Shares Available for Issuance, Restricted stock units granted	(9,932,561)	(480,456)
Options exercised	(2,817,915)	(1,089,708)	(695,482)
Exercised, withheld in net settlement	9,019
Number of Shares Available for Issuance, Canceled	3,208,006	1,178,737	1,815,795
Number of Shares Available for Issuance, Restricted stock units canceled	1,653,927	1,667
Number of Shares Available for Issuance, Repurchased	12,545	66,088	108,037
Number of Shares Available for Issuance, Ending Balance	6,672,236	7,392,158	2,085,338	574,597
Options Outstanding, Number, Ending Balance	11,498,747	16,435,568	13,330,882	10,950,917
Vested and exercisable- end of the period	7,167,464
Vested and expected to vest - end of the period	11,032,059
Options Activity, Weighted Average Exercise Price Rollforward
Options Outstanding, Weighted-Average Exercise Price, Beginning Balance	$ 4.15	$ 2.90	$ 2.11
Options Outstanding, Weighted Average Exercise Price Granted	6.95	6.97	4.33
Options Outstanding, Weighted Average Exercise Price Exercised	2.12	2.27	1.72
Options Outstanding, Weighted Average Exercise Price Canceled	5.61	4.55	2.55
Options Outstanding, Weighted-Average Exercise Price, Ending Balance	4.51	$ 4.15	$ 2.90	$ 2.11
Options Outstanding, Weighted-Average Exercise Price, Vested and exercisable	3.55
Options Outstanding, Weighted-Average Exercise Price, Vested and expected to vest	$ 4.43
Options Outstanding, Weighted-Average Remaining Contractual Term (Years)	6 years 10 months 10 days	7 years 9 months 29 days	8 years 4 months 17 days	8 years 9 months 11 days
Options Outstanding, Aggregate Intrinsic Value	$ 6,256	$ 95,791	$ 38,339	$ 17,329
Options Outstanding, Vested and exercisable, Aggregate Intrinsic Value	6,202
Options Outstanding, Vested and expected to vest, Aggregate Intrinsic Value	$ 6,250
Stock Issued During Period Shares Stock Options Early Exercised	0	42,772	126,386