Stock Plans and Stock-Based Compensation - Summary of Status of Stock Options Granted Under All Plans (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) $ / shares shares
Shares
Shares, outstanding at beginning of year (in shares) | shares	4,656,405
Shares, granted (in shares) | shares	675,358
Shares, exercised (in shares) | shares	(1,130,939)
Shares, forfeited or expired (in shares) | shares	(83,627)
Shares, outstanding at end of year (in shares) | shares	4,117,197
Shares, fully vested and exercisable (in shares) | shares	2,684,405
Shares, fully vested, exercisable and expected to vest (in shares) | shares	4,002,574
Weighted Average Exercise Price
Weighted average exercise price, outstanding at beginning of year (in dollars per share) | $ / shares	$ 15.02
Weighted average exercise price, granted (in dollars per share) | $ / shares	26.87
Weighted average exercise price, exercised (in dollars per share) | $ / shares	13.79
Weighted average exercise price, forfeited or expired (in dollars per share) | $ / shares	20.50
Weighted average exercise price, outstanding at end of year (in dollars per share) | $ / shares	17.19
Weighted average exercise price, fully vested and exercisable (in dollars per share) | $ / shares	15.90
Weighted average exercise price, fully vested, exercisable and expected to vest (in dollars per share) | $ / shares	$ 17.12
Aggregate intrinsic value, outstanding at end of year | $	$ 30,825
Aggregate intrinsic value, fully vested and exercisable | $	22,730
Aggregate intrinsic value, fully vested, exercisable and expected to vest | $	$ 30,177
Average remaining contractual life, outstanding at end of year	6 years 9 months
Average remaining contractual life, fully vested and exercisable	6 years 18 days
Average remaining contractual life, fully vested, exercisable and expected to vest	6 years 8 months 16 days