Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Operating activities
Net loss	$ (49,851)	$ (36,675)
Adjustments to reconcile net loss to cash used in operating activities:
Share-based Payment Arrangement, Noncash Expense	11,223	12,482
Depreciation and amortization	765	772
Deferred income taxes	(1,061)	(784)
Amortization of right-of-use assets	2,704	2,603
Changes in operating assets and liabilities:
Accounts receivable	12	2
Prepaid and other assets	(3,760)	(15,593)
Accounts payable, accruals and other liabilities	589	10,414
Restructuring liability	0	(461)
Operating lease liabilities	(2,485)	(2,298)
Net cash used in operating activities	(41,864)	(29,538)
Investing activities
Purchases of property and equipment	(68)	(200)
Proceeds from disposal of fixed assets	0	8
Net cash used in investing activities	(68)	(192)
Financing activities
Proceeds from issuance of ordinary shares upon exercise of stock options	151	215
Net cash provided by financing activities	151	215
Net decrease in cash, cash equivalents and restricted cash	(41,781)	(29,515)
Cash, cash equivalents and restricted cash, beginning of the year	378,427	431,715
Cash, cash equivalents and restricted cash, end of the period	336,646	402,200
Supplemental disclosures of cash flow information
Cash paid for income taxes, net	417	755
Supplemental disclosures of non-cash investing and financing activities
Acquisition of property and equipment included in accounts payable and accrued liabilities	43	12
Right-of-use assets recorded upon adoption of ASC 842	0	28,530
Reduction of build-to-suit lease obligation upon adoption of ASC 842	0	(51,546)
Reduction of amounts capitalized under build-to-suit lease upon adoption of ASC 842	0	(46,760)
Reduction of capitalized interest under build-to-suit lease upon adoption of ASC 842	0	(1,099)
Total cash, cash equivalents and restricted cash, end of the period	$ 336,646	$ 402,200