Share-Based Compensation Plans - Stock Options (Details) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($) $ / shares shares
Number of Shares
Number of shares outstanding beginning balance | shares	2,443
Number of shares granted | shares	2,735
Number of shares exercised | shares	(27)
Number of shares forfeited or expired | shares	0
Number of shares outstanding ending balance | shares	5,151
Number of shares fully vested and expected to vest | shares	4,962
Number of shares exercisable | shares	1,671
Weighted-Average Exercise Price Per Share
Weighted average exercise price per share outstanding beginning balance (in dollars per share) | $ / shares	$ 6.93
Weighted average exercise price per share granted (in dollars per share) | $ / shares	9.86
Weighted average exercise price per share exercised (in dollars per share) | $ / shares	5.49
Weighted average exercise price per share forfeited or expired (in dollars per share) | $ / shares	0.00
Weighted average exercise price per share outstanding ending balance (in dollars per share) | $ / shares	8.49
Weighted average exercise price per share fully vested and expected to vest (in dollars per share) | $ / shares	8.45
Weighted average exercise price per share exercisable (in dollars per share) | $ / shares	$ 7.30
Aggregate Intrinsic Value
Weighted average remaining contractual term outstanding	7 years 11 months 16 days
Weighted average remaining contractual term fully vested and expected to vest	7 years 10 months 21 days
Weighted average remaining contractual term exercisable	4 years 7 months 10 days
Aggregate intrinsic value outstanding ending balance (in dollars) | $	$ 15,973
Aggregate intrinsic value fully vested and expected to vest (in dollars) | $	15,580
Aggregate intrinsic value exercisable (in dollars) | $	$ 7,190