Stockholders' Equity - Stock Option Activity (Details) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended
	Sep. 29, 2018 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Balance, beginning of period (in shares) | shares	21,386
Granted (in shares) | shares	0
Exercised (in shares) | shares	(2,339)
Canceled (in shares) | shares	(582)
Balance, end of period (in shares) | shares	18,465
Options exercisable (in shares) | shares	18,455
Options vested and expected to vest (in shares) | shares	16,758
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Balance, weighted average exercise price, beginning of period (in dollars per share)	$ 3.01
Granted, weighted average exercise price (in dollars per share)	0.00
Exercised, weighted average exercise price (in dollars per share)	2.33
Canceled, weighted average exercise price (in dollars per share)	7.05
Balance, weighted average exercise price, end of period (in dollars per share)	2.97
Options exercisable, weighted average exercise price (in dollars per share)	2.97
Options vested and expected to vest, weighted average exercise price (in dollars per share)	$ 2.72
Options outstanding, aggregate intrinsic value, end of period | $	$ 50,236
Options exercisable, aggregate intrinsic value | $	50,219
Options vested and expected to vest, aggregate intrinsic value | $	$ 48,539
Fair value of the Class A common stock (in dollars per share)	$ 5.35