Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 393,504	$ 140,406
Short-term marketable securities	225,417	472,213
Prepaid expenses and other current assets	12,226	4,928
Total current assets	631,147	617,547
Restricted cash	466	466
Long-term marketable securities	317,511	79,995
Other investments	83,448	83,448
Property and equipment, net	115,857	77,045
Right-of-use assets, net	47,236	47,010
Other non-current assets	2,669	2,769
Total assets	1,198,334	908,280
Current liabilities:
Accounts payable	3,526	9,396
Accrued liabilities and other current liabilities	25,058	28,021
Success payment liabilities	25,116	5,773
Deferred revenue	5,581	6,095
Total current liabilities	59,281	49,285
Operating lease liabilities, non-current	65,684	50,957
Deferred revenue, non current	81,883	89,066
Other non-current liabilities	5,012	532
Total liabilities	211,860	189,840
Commitments and contingencies (Note 12)
Convertible preferred stock, $0.0001 par value; no and 195,021 shares authorized at September 30, 2021 and December 31, 2020, respectively; no and 194,474 shares were issued and outstanding at September 30, 2021 and at December 31, 2020, respectively	0	1,010,968
Stockholders' deficit:
Preferred stock: $0.0001 par value, 0 and no shares authorized at September 30, 2021 and December 31, 2020, respectively; no shares issued and outstanding at September 30, 2021 and December 31, 2020	0	0
Common stock, $0.0001 par value; 264,905 shares authorized at September 30, 2021 and December 31, 2020, respectively; 239,789 and 15,570 shares issued and outstanding at September 30, 2021 and December 31, 2020, respectively	24	2
Additional paid-in capital	1,487,171	41,357
Accumulated other comprehensive (loss) income	(65)	256
Accumulated deficit	(500,656)	(334,143)
Total stockholders' deficit	986,474	(292,528)
Total liabilities, convertible preferred stock and stockholders' deficit	$ 1,198,334	$ 908,280

Success payment current liabilities.

No definition available.

Name:	lyel_SuccessPaymentCurrentLiabilities
Namespace Prefix:	lyel_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).