Collaboration and License Arrangements - Additional Information (Detail) - USD ($)		1 Months Ended	3 Months Ended	12 Months Ended
	May 13, 2021	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020
Collaboration And License Arrangement [Line Items]
Collaboration revenue				$ 3,029,000	$ 82,654,000
Contract asset		$ 4,537,000		4,537,000	7,654,000
Other liabilities		15,000,000		$ 15,000,000
EQRx, Inc [Member]
Collaboration And License Arrangement [Line Items]
Collaborative arrangement, purpose				In August 2021, the Company and EQRx, Inc. (“EQRx”) entered into the Discovery Collaboration Agreement (“Collaboration Agreement”) to discover, develop, and commercialize novel medicines against validated oncology targets.
Collaborative arrangement, rights and obligations				Under the terms of the Collaboration Agreement, the Company is responsible for the discovery collaboration phase through to filing of the application for an Investigational New Drug (“IND”), while EQRx is responsible for clinical development, regulatory and commercialization of the product candidates under the collaboration. Subject to certain opt-out rights, the Company and EQRx share equally in the discovery, development and commercialization costs, as well as the net profits and losses from sales of any collaboration medicines, if approved. The Company retains the right to develop any collaboration medicines in combination with its wholly-owned pipeline.
Genentech [Member] | Genentech Agreement [Member]
Collaboration And License Arrangement [Line Items]
Collaborative arrangement, purpose				On December 11, 2020, the Company entered into the Genentech Agreement, which granted Genentech a license to develop and commercialize RLY-1971.
Collaborative arrangement, rights and obligations				RLY-1971 is currently being developed in a Phase 1a clinical trial for patients with advanced solid tumors (the “Phase 1a Trial”). Unless Genentech elects to exercise its option to conduct the remainder of the ongoing Phase 1a Trial, the Company is responsible for the completion of this trial. Genentech is responsible for conducting all subsequent clinical development of RLY-1971. The Company is also responsible for the one-time transfer of the active pharmaceutical ingredient (“API”) and other materials related to RLY-1971 to Genentech.
Non-refundable upfront payment				$ 75,000,000.0
Milestone payment receivable				5,000,000.0
Maximum additional amount received upon milestone achievement				695,000,000.0
Collaboration agreement transaction price				86,500,000
Non-refundable milestone payment transfer amount	$ 5,000,000.0			5,000,000.0
Non-refundable milestone payment for completion amount				5,000,000.0
Variable consideration related to reimbursements due for research and development services				1,500,000
Development based milestone payments under agreement				0
Regulatory based milestone payments under agreement				0
Collaboration revenue				2,600,000	82,700,000
Milestone payment received		15,000,000.0
Other liabilities		15,000,000.0		15,000,000.0
Genentech [Member] | Genentech Agreement [Member] | Research and Development Services [Member]
Collaboration And License Arrangement [Line Items]
Collaboration revenue				1,700,000	0
Genentech [Member] | Genentech Agreement [Member] | Transfer of Active Pharmaceutical Ingredients [Member]
Collaboration And License Arrangement [Line Items]
Collaboration revenue			$ 300,000		$ 0
Contract asset		4,500,000		4,500,000
Genentech [Member] | Genentech Agreement [Member] | Stand-alone Selling Prices ("SSP") [Member]
Collaboration And License Arrangement [Line Items]
Collaboration agreement transaction price				86,500,000
Genentech [Member] | Genentech Agreement [Member] | Stand-alone Selling Prices ("SSP") [Member] | Transfer of License [Member]
Collaboration And License Arrangement [Line Items]
Remaining performance obligations		83,300,000		83,300,000
Genentech [Member] | Genentech Agreement [Member] | Stand-alone Selling Prices ("SSP") [Member] | Research and Development Services [Member]
Collaboration And License Arrangement [Line Items]
Remaining performance obligations		2,900,000		2,900,000
Genentech [Member] | Genentech Agreement [Member] | Stand-alone Selling Prices ("SSP") [Member] | Transfer of Active Pharmaceutical Ingredients [Member]
Collaboration And License Arrangement [Line Items]
Remaining performance obligations		$ 300,000		300,000
Genentech [Member] | Genentech Agreement [Member] | Outside US [Member]
Collaboration And License Arrangement [Line Items]
Maximum additional amount received upon milestone achievement				$ 410,000,000.0