Stock-Based Compensation - Restricted Stock Units (Details) - Restricted stock units shares in Thousands	3 Months Ended
	Mar. 31, 2019 $ / shares shares
Shares
Balance (in shares) | shares	1,084
Granted (in shares) | shares	1,202
Vested (in shares) | shares	(187)
Canceled/Forfeited (in shares) | shares	(14)
Balance (in shares) | shares	2,085
Weighted Average Grant Date Fair Value
Balance (in dollars per share) | $ / shares	$ 11.72
Granted (in dollars per share) | $ / shares	18.35
Vested (in dollars per share) | $ / shares	9.46
Canceled/Forfeited (in dollars per share) | $ / shares	11.70
Balance (in dollars per share) | $ / shares	$ 15.74