Consolidated balance sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents (Note 3)	$ 52,032	$ 32,301
Short-term investments (Note 11)	56,053	70,758
Receivables, prepayments and deposits	740	426
Total current assets	108,825	103,485
Property and equipment, net (Note 4)	905	849
Long-term prepayments and deposits	599
Long-term investments (Note 11)		50,046
Total assets	110,329	154,380
Current liabilities
Accounts payable and other liabilities (Note 5)	10,956	9,519
Total current liabilities	10,956	9,519
Other liabilities (Note 6)	486	197
Total liabilities	11,442	9,716
Commitments and contingencies (Note 13)
Share capital:
Common stock	0
Preferred stock	0
Additional paid-in capital	297,459	293,111
Accumulated deficit	(198,502)	(148,278)
Accumulated other comprehensive loss	(70)	(169)
Total stockholders' equity	98,887	144,664
Total liabilities and stockholders' equity	$ 110,329	$ 154,380