CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Operating Activities:
Net loss	$ (140,801)	$ (80,447)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation and amortization	6,675	3,999
Amortization of premium (discount) on marketable securities	2,394	(1,344)
Amortization and other changes in operating lease right-of-use assets	6,104	5,706
Gain on free shares	(18)	(31)
Stock-based compensation	24,880	19,066
(Gain) loss on disposal of property and equipment	(30)	197
Net changes in operating assets and liabilities:
Interest receivable	415	(140)
Accounts receivable	(2,743)	(2,578)
Prepaid expenses and other assets	(6,467)	(9,098)
Accounts payable and other accrued liabilities	(4,699)	1,336
Accrued compensation and employee benefits	(1,932)	4,186
Deferred revenues	(62,292)	235,551
Long-term portion of lease liabilities	(3,227)	(2,760)
Other non-current liabilities	1,204	527
Net cash (used in) provided by operating activities	(180,537)	174,170
Investing Activities:
Purchases of marketable securities	(300,387)	(335,002)
Maturities of marketable securities	509,620	205,039
Sales of marketable securities	6,870	0
Purchases of property and equipment	(20,420)	(10,703)
Purchase of additional shares of Sangamo France	(119)	(503)
Net cash provided by (used in) investing activities	195,564	(141,169)
Financing Activities:
Taxes paid related to net share settlement of equity awards	(2,988)	(573)
Proceeds from exercise of stock options and restricted stock units	4,582	3,041
Net cash provided by financing activities	30,746	146,181
Effect of exchange rate changes on cash, cash equivalents, and restricted cash	(148)	(217)
Net increase in cash, cash equivalents, and restricted cash	45,625	178,965
Cash, cash equivalents, and restricted cash, beginning of period	132,829	81,928
Cash, cash equivalents, and restricted cash, end of period	178,454	260,893
Supplemental cash flow disclosures:
Property and equipment included in unpaid liabilities	650	899
Right-of-use assets obtained in exchange for lease obligations	1,349	0
Buy-out of non-controlling interest	943	0
At the Market Offering
Financing Activities:
Proceeds from issuance of common stock	27,099	0
Biogen Collaboration Agreement
Financing Activities:
Proceeds from issuance of common stock	0	142,526
Employee Stock
Financing Activities:
Proceeds from issuance of common stock	$ 2,053	$ 1,187