Computation of Net Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Computation of Net Earnings per Share
Net income available to common stockholders	$ 6,062	$ 13,915
Weighted average common shares outstanding used in computing basic income per share	32,683	32,094
Incremental options and RSUs	1,541	2,029
Weighted average common shares used in computing diluted net income per share	34,224	34,123
Net income per share
Basic	$ 0.19	$ 0.43
Diluted	$ 0.18	$ 0.41
Weighted average number diluted shares outstanding adjustment	10	10