Net Income per Share - Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Earnings Per Share [Abstract]
Net income	$ 8,528	$ 5,849	$ 15,554	$ 10,778
Weighted Average Number of Shares Outstanding, Basic [Abstract]
Weighted-average shares of common stock outstanding	31,343	32,772	31,359	32,762
Shares used in computing basic net income per share	31,343	32,772	31,359	32,762
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Restricted stock subject to vesting	495	552	558	576
Shares issuable for acquisition consideration (in shares)	202	565	249	556
Shares used in computing diluted net income per share	32,040	33,889	32,166	33,894
Basic net income per share (in dollars per share)	$ 0.27	$ 0.18	$ 0.50	$ 0.33
Diluted net income per share (in dollars per share)	$ 0.27	$ 0.17	$ 0.48	$ 0.32