CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
ASSETS
Accounts receivable, allowance for doubtful accounts	$ 582	$ 463
Shareholders' equity:
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	1,000,000.0	1,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	99,000,000.0	99,000,000
Common stock, shares issued (in shares)	2,742,857	2,758,275
Common stock, shares outstanding (in shares)	2,702,940	2,688,790
Treasury stock, shares (in shares)	39,917	69,485