Stock-Based Compensation - Summary of Stock Option and Restricted Stock Units Award Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Shares Available for Grant
Beginning balance	4,425,155
Increase in shares authorized	3,727,989
Options granted	(801,000)
Options canceled or expired	69,869
RSUs granted	(2,018,982)
RSUs canceled or expired	155,766
RSUs withheld for taxes	524,090
Ending balance	6,082,887	4,425,155
Number of Shares
Beginning balance	7,412,228
Options granted	801,000
Options exercised	(229,658)
Options canceled or expired	(69,869)
Ending balance	7,913,701	7,412,228
Vested and exercisable at the end of period	5,459,769
Weighted Average Exercise Price
Beginning balance	$ 10.36
Options granted	13.10
Options exercised	7.29
Options canceled or expired	11.54
Ending balance	10.72	$ 10.36
Vested and exercisable at the end of period	$ 10.23
Weighted Average Remaining Contractual Term (Years) / Aggregate Intrinsic Value
Weighted Average Remaining Contractual Term (Years)	6 years 2 months 19 days	6 years 1 month 2 days
Vested and exercisable at the end of period	5 years 25 days
Aggregate Intrinsic Value, Beginning balance	$ 25,415
Aggregate Intrinsic Value, Options exercised	1,318
Aggregate Intrinsic Value, Ending balance	30,327	$ 25,415
Vested and exercisable at the end of period	$ 27,111
Restricted Stock Units, Number of Shares
RSUs granted	2,018,982
RSUs canceled or expired	(155,766)
Restricted Stock Units
Shares Available for Grant
RSUs granted	(2,018,982)
RSUs vested	1,342,056
RSUs canceled or expired	155,766
Restricted Stock Units, Number of Shares
Beginning balance	5,194,292
RSUs granted	2,018,982
RSUs vested	(1,342,056)
RSUs canceled or expired	(155,766)
Ending balance	5,715,452	5,194,292
Weighted Average Grant Date Fair Value
Beginning Balance	$ 12.26
RSUs granted	13.06
RSUs vested	13.49
RSUs canceled or expired	11.33
Ending balance	$ 12.28	$ 12.26