CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 378,021	$ 88,980
Short-term marketable securities	127,255	259,586
Accounts receivable, net of allowances of $0 and $992 at December 31, 2018 and 2017, respectively	620	2,253
Receivables from collaborative arrangements	10,053	7,109
Prepaid taxes	310	291
Other prepaid and current assets	16,564	3,700
Inventories	0	16,830
Total current assets	532,823	378,749
Property and equipment, net	13,176	10,157
Long-term marketable securities	11,869	41,587
Tax receivable		8,191
Restricted cash	833	833
Other assets	1,534	1,883
Total assets	560,235	441,400
Current liabilities:
Accounts payable	9,028	5,924
Accrued personnel-related expenses	23,803	24,136
Accrued clinical and development expenses	11,876	20,657
Other accrued liabilities	10,445	11,710
Deferred revenue	43,402	125
Total current liabilities	98,554	62,552
Convertible senior notes due 2023, net	224,818	223,746
Non-recourse notes due 2033, net	229,535
Deferred rent	7,976	3,668
Long-term deferred revenue	26,179	1,436
Other long-term liabilities	24,762	34,820
Commitments and contingencies (Notes 2, 11 and 13)
Shareholders’ (Deficit) Equity
Preferred shares, $0.00001 par value: 230 shares authorized, no shares issued or outstanding at December 31, 2018 and 2017, respectively
Ordinary shares, $0.00001 par value: 200,000 shares authorized; 55,681 and 54,381 shares issued and outstanding at December 31, 2018 and 2017, respectively	1	1
Additional paid-in capital	960,721	913,650
Accumulated other comprehensive loss	(166)	(733)
Accumulated deficit	(1,012,145)	(797,740)
Total shareholders’ (deficit) equity	(51,589)	115,178
Total liabilities and shareholders’ (deficit) equity	$ 560,235	$ 441,400