Equity Award Plan Activities - Option and RSA Activity Rollforward (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Number of Shares Underlying Outstanding Options and RSAs (in thousands)
Options granted (in shares)	165
Options canceled (in shares)	(223)
Employee Stock Option and Restricted Stock
Number of Shares Underlying Outstanding Options and RSAs (in thousands)
Beginning balance, options (in shares)	9,509
Options granted (in shares)	165
Options exercised (in shares)	(882)
Options canceled (in shares)	(223)
Ending balance, options (in shares)	8,569	9,509
Vested and exercisable (in shares)	3,144
Vested and expected to vest (in shares)	8,569
Weighted- Average Exercise Price per Share
Outstanding beginning balance (usd per share)	$ 28.79
Options granted (usd per share)	95.51
Options exercised (usd per share)	15.32
Options canceled (usd per share)	32.10
Outstanding ending balance (usd per share)	31.38	$ 28.79
Vested and exercisable (usd per share)	16.75
Vested and expected to vest (usd per share)	$ 31.38
Weighted- Average Remaining Contractual Term and Aggregate Intrinsic Value of Stock Options Outstanding
Weighted-average remaining contractual term of stock options outstanding	6 years 10 months	6 years 10 months 24 days
Weighted-average remaining contractual term of stock options vested and exercisable	6 years
Weighted-average remaining contractual term of stock options vested and expected to vest	6 years 10 months
Aggregate intrinsic value of stock options outstanding	$ 864,597	$ 646,394
Aggregate intrinsic value of stock options outstanding vested and exercisable	363,194
Aggregate intrinsic value of stock options outstanding vested and expected to vest	$ 864,597