Cover Page - shares	6 Months Ended
	Jun. 30, 2023	Jul. 31, 2023
Cover [Abstract]
Amendment Flag	true
Document Type	10-Q/A
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q2
Entity Central Index Key	0000730272
Current Fiscal Year End Date	--12-31
Document Period End Date	Jun. 30, 2023
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Securities Act File Number	000-14656
Entity Registrant Name	REPLIGEN CORP
Entity Filer Category	Large Accelerated Filer
Trading Symbol	RGEN
Title of 12(b) Security	Common Stock
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	04-2729386
Entity Address, Address Line One	41 Seyon Street, Bldg. 1, Suite 100
Entity Address, City or Town	Waltham
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02453
City Area Code	781
Entity Shell Company	false
Smaller reporting company	false
Emerging growth company	false
Local Phone Number	250-0111
Document Quarterly Report	true
Document Transition Report	false
Entity Common Stock, Shares Outstanding		55,756,322
Amendment Description	Repligen Corporation (“we,” “us,” “our,” or the “Company”) is filing this Amendment No. 1 on Form 10-Q/A (the “Amendment”) to amend and restate certain items in our Quarterly Report on Form 10-Q as of and for the three and six month periods ended June 30, 2023, originally filed with the U.S. Securities and Exchange Commission (the “SEC”) on August 2, 2023 (the “Original Report”), as listed in “Items Amended in this Filing” below. In filing this Amendment, we are restating our previously issued unaudited condensed consolidated financial statements as of and for the three and six months ended June 30, 2023 to correct the misapplication of accounting principles under U.S. GAAP related to the timing of revenue recognition arising from a specific COVID-related cancellation payment, received in connection with a contract modification (collectively, the "Misstatement"), as further described in Note 1 to the unaudited condensed consolidated financial statements herein. This restatement changes the timing of recognition of revenue, including the revenue reported in the Original Report, but will not change the total revenue to be recognized for this payment, nor have any impact on the Company’s previously reported cash and cash equivalent balances. This misapplication did not result from any override of controls, misconduct, or fraud of any kind. In connection with the restatement, the Company determined that it was appropriate to revise the condensed consolidated balance sheet as of December 31, 2022 and the condensed consolidated statement of cash flows for the six month period ended June 30, 2022, as well as impacted footnote disclosures, in this Form 10-Q/A to correct other unrelated immaterial errors. In addition, we have filed an amendment to our Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2023, originally filed with the SEC on May 2, 2023, and we are filing an amendment to our Annual Report on Form 10-K for the year ended December 31, 2023, originally filed with SEC on February 22, 2024, and amendments to our Quarterly Reports on Form 10-Q for quarterly periods ended September 30, 2023, originally filed with the SEC on October 31, 2023; March 31, 2024, originally filed with the SEC on May 1, 2024; and June 30, 2024, originally filed with the SEC on July 30, 2024. In correcting the Misstatement in this Amendment, we have also restated other financial statement line item amounts including but not limited to product revenues, income tax provision, net income, foreign currency translation, deferred revenues, prepaid expenses, deferred taxes and earnings-per-share.