Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Consolidated Balance Sheets [Abstract]
Accounts receivable, allowances	$ 166	$ 147
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	75,000,000	75,000,000
Common stock, shares issued	46,964,115	46,637,549
Common stock, shares outstanding	36,031,933	41,101,975
Treasury stock, shares	10,932,182	5,535,574