CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Accounts receivable, allowance	$ 772	$ 842
Stockholders' equity:
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common shares, authorized (in shares)	230,000,000	230,000,000
Common shares, issued (in shares)	38,005,623	36,182,783
Common shares, outstanding (in shares)	38,005,623	36,182,783