CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
CONSOLIDATED BALANCE SHEETS
Accounts receivable, allowances	$ 0	$ 0
Preferred shares, par value (in dollars per share)	$ 0.00001	$ 0.00001
Preferred shares, shares authorized	230	230
Preferred shares, shares issued	0	0
Preferred shares, outstanding shares	0	0
Ordinary shares, par value (in dollars per share)	$ 0.00001	$ 0.00001
Ordinary shares, authorized shares	200,000	200,000
Ordinary shares, shares issued	57,015	55,681
Ordinary shares, outstanding shares	57,015	55,681