Sutro Biopharma, Inc. Annual report pursuant to Section 13 and 15(d)

Annual report pursuant to Section 13 and 15(d)

Collaboration and License Agreements and Supply Agreements - Additional Information (Details)

Collaboration and License Agreements and Supply Agreements - Additional Information (Details)		1 Months Ended											3 Months Ended								12 Months Ended
	Oct. 01, 2018 USD ($) $ / shares shares	Sep. 30, 2019 USD ($)	May 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Aug. 31, 2018 USD ($)	Jul. 31, 2018 Program	Sep. 30, 2017 USD ($)	Aug. 31, 2017 USD ($) Program	Jun. 30, 2016 USD ($)	Mar. 31, 2015 USD ($)	Sep. 30, 2014 USD ($)	May 31, 2014 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($)	Jan. 01, 2019 USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenues																					$ 42,736,000	$ 38,419,000	$ 51,741,000
Total revenue													$ 11,305,000	$ 12,277,000	$ 10,525,000	$ 8,629,000	$ 19,086,000	$ 7,836,000	$ 5,704,000	$ 5,793,000
Receivables from agreement				$ 2,489,000									6,298,000				2,489,000				6,298,000	2,489,000
Proceeds from issuance of redeemable convertible preferred stock gross																						84,739,000
Accounts receivable				2,489,000													2,489,000					2,489,000
Accounts receivable, related parties				959,000									1,050,000				959,000				1,050,000	959,000
Contingent payments of embedded derivative and related liability				100,000									100,000				100,000				100,000	100,000
EMD Serono
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Changes in deferred revenue																					600,000
Accounts receivable				900,000									1,500,000				900,000				$ 1,500,000	$ 900,000
The Leukemia & Lymphoma Society, Inc.
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research development and commercialization agreement termination period																					12 years
Research development and commercialization agreement termination description																					The LLS Agreement terminates upon the earlier of (a) fulfillment of all payment obligations by both parties or (b) 12 years after the effective date. LLS may terminate the LLS Agreement at any time with 60 days’ prior written notice. Either the Company or LLS has the right to terminate the LLS Agreement based on the other party’s uncured material breach.
Common Stock
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Stock Issued, shares \| shares																						5,667,000
SutroVax
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Receivables from agreement				49,000									14,000				49,000				$ 14,000	$ 49,000
Accounting Standards Update 2014-09
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenues																					43,484,000
Accounts receivable																								$ 2,489,000
Accounting Standards Update 2014-09 \| Difference between Revenue Guidance in Effect before and after Topic 606
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenues																					(748,000)
Celgene Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront, nonrefundable payment received											$ 83,100,000
Contingent payment received										$ 15,000,000.0
Milestone payment received									$ 25,000,000.0
Additional milestone payment received									$ 10,000,000.0
Option fee payment received								$ 12,500,000
Milestone revenue recognized				10,000,000.0			$ 10,000,000.0
Number of programs advancing through preclinical development \| Program								4
Contingent payments			$ 275,000,000.0
Option maintenance fee								$ 12,500,000
Deferred revenue				11,400,000				8,200,000					3,000,000.0				11,400,000				3,000,000.0	11,400,000
Revenue, remaining performance obligation, amount								20,700,000
Celgene Agreement \| Bristol-Myers Squibb Company ("BMS")
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Receivables from agreement				600,000									1,700,000				600,000				1,700,000	600,000
Celgene Agreement \| Partially Unsatisfied Performance Obligations
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenues																					3,900,000
Celgene Agreement \| Performance Under Deliverables
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenue																						16,600,000	43,900,000
Celgene Agreement \| Accounting Standards Update 2014-09 \| Difference between Revenue Guidance in Effect before and after Topic 606
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Deferred revenue																								(4,500,000)
Celgene Agreement \| First Performance Obligation
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue, remaining performance obligation, amount								8,200,000
Celgene Agreement \| Future Services on Collaboration Joint Steering Committee ("JSC")
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue, remaining performance obligation, amount								200,000
Celgene Agreement \| Third Performance Obligation
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue, remaining performance obligation, amount								$ 12,300,000
2018 Celgene Master Services Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Other revenue-related parties																					6,800,000	4,500,000
2018 Celgene Master Services Agreement \| Bristol-Myers Squibb Company ("BMS")
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Receivables from agreement				0									2,000,000.0				0				2,000,000.0	0
2018 Merck Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Deferred revenue				53,000,000.0									31,900,000				53,000,000.0				31,900,000	53,000,000.0
Receivables from agreement				900,000									1,000,000.0				900,000				1,000,000.0	900,000
2018 Merck Agreement \| Merck Sharp & Dohme Corp
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of research programs \| Program						3
Upfront payment received					$ 60,000,000.0																60,000,000.0
Revenue from first performance obligation					7,300,000
Recognition of up front payment					47,100,000
Revenue performance obligation amounts recognized in revenues					700,000
Extension option fee associated with contingent program					4,900,000
Embedded interest associated with upfront payment																					3,100,000	0
FTE Funding Received																					3,600,000	1,500,000
Revenue recognition aggregate milestone payments eligible to receive																					$ 1,600,000,000
Milestone method revenue recognition description																					If one or more products from each of the target programs are developed for non-oncology or a single indication, the Company will be eligible for reduced aggregate milestone payments. In addition, the Company is eligible to receive tiered royalties ranging from mid-single digit to low teen percentages on the worldwide sales of any commercial products that may result from the collaboration.
2018 Merck Agreement \| Merck Sharp & Dohme Corp \| Common Stock \| Private Placement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Stock Issued, shares \| shares	666,666
Share issue price per share \| $ / shares	$ 15.00
Proceeds from issuance of common stock	$ 10,000,000.0
2018 Merck Agreement \| Merck Sharp & Dohme Corp \| Series E Redeemable Convertible Preferred Stock
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Stock Issued, shares \| shares	74,794,315
Share issue price per share \| $ / shares	$ 0.2674
Proceeds from issuance of redeemable convertible preferred stock gross	$ 20,000,000.0
2018 Merck Agreement \| Partially Unsatisfied Performance Obligations \| Merck Sharp & Dohme Corp
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenue																					$ 14,700,000	7,000,000.0
2018 Merck Agreement \| Accounting Standards Update 2014-09 \| Merck Sharp & Dohme Corp
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total interest expense of unearned revenue													7,100,000								7,100,000
2018 Merck Agreement \| Accounting Standards Update 2014-09 \| Celgene
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Changes in deferred revenue due to adoption of new accounting policy																								$ 6,300,000
Collaboration Agreement \| EMD Serono
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Up-front, nonrefundable and non-creditable payment received												$ 10,000,000.0
MDA Agreement \| EMD Serono
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contingent payment received		$ 1,500,000
Deferred revenue				1,700,000									800,000				1,700,000				800,000	1,700,000
Up-front, nonrefundable and non-creditable payment received											$ 10,000,000.0
Maximum amount eligible to receive for each product developed																					52,500,000
Milestone Payment and New Supply Agreement \| EMD Serono
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenue																					3,700,000
Partially Unsatisfied Performance Obligations \| EMD Serono
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenue																					2,300,000
Performance Under Deliverables \| EMD Serono
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenue																						4,100	4,100
Research and Development Services \| EMD Serono
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Total revenue																					2,900,000	3,100,000	$ 3,000,000.0
Supply Agreement \| EMD Serono
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Deferred revenue				1,700,000									800,000				1,700,000				800,000	1,700,000
Supply Agreement \| SutroVax
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Other revenue-related parties																					1,100,000	1,500,000
Accounts receivable, related parties				$ 49,000									$ 14,000				$ 49,000				14,000	$ 49,000
Research Development and Commercialization Agreement \| The Leukemia & Lymphoma Society, Inc.
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payment received																					1,000,000.0
Maximum contribution in clinical development					6,000,000.0																6,000,000.0
Initial milestone payment					$ 500,000
Maximum aggregate payment																					$ 19,500,000