Stockholders' Equity - Stock Options Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Summary of stock option activity under all stock plans
Underlying shares outstanding, Beginning balance	1,970
Underlying shares, exercised	(1,556)
Underlying shares, cancelled	(4)
Underlying shares outstanding, Ending balance	410	1,970
Underlying shares exercisable, Ending balance	410
Underlying shares vested or expected to vest, Ending balance	410
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Weighted average exercise price outstanding, Beginning balance	$ 34.91
Weighted Average Exercise Price, exercised	34.95
Weighted Average Exercise Price, cancelled	18.92
Weighted Average Exercise Price outstanding, Ending balance	34.93	$ 34.91
Weighted Average Exercise Price option exercisable, Ending balance	34.93
Weighted Average Exercise price vested or expected to vest, Ending balance	$ 34.93
Weighted Average Remaining Contractual Term outstanding, Beginning balance	2 years 5 months 19 days	2 years 11 months 27 days
Weighted Average Remaining Contractual Term exercisable, Ending balance	2 years 5 months 19 days
Weighted Average Remaining Contractual Term vested or expected to vest, Ending balance	2 years 5 months 19 days
Aggregate Intrinsic Value outstanding	$ 13,292	$ 37,820
Aggregate intrinsic value exercisable	13,292
Aggregate intrinsic value vested or expected to vest	$ 13,292