Net Income Per Share - Narrative (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Earnings Per Share [Abstract]
Net income	$ 15,976	$ 3,284	$ 6,588	$ 2,720	$ 19,260	$ 9,308
Weighted-average shares outstanding — basic (in shares)	41,371		38,970		41,033	38,804
Effect of dilutive securities from stock award plans (in shares)	1,574		1,030		1,613	1,050
Weighted-average shares outstanding — diluted (in shares)	42,945		40,000		42,646	39,854
Net income per share - basic (in dollars per share)	$ 0.39		$ 0.17		$ 0.47	$ 0.24
Net income per share - diluted (in dollars per share)	$ 0.37		$ 0.16		$ 0.45	$ 0.23
Anti-dilutive weighted-average shares related to stock award plans (in shares)	741		1,264		748	1,249