Debt (Narrative) (Details)				1 Months Ended							3 Months Ended				9 Months Ended			12 Months Ended
	Jul. 10, 2020 EUR (€)	Jul. 14, 2018 USD ($)	Jun. 11, 2018 USD ($)	Jun. 17, 2020 shares	Feb. 24, 2020 $ / shares shares	Jun. 30, 2019 EUR (€)	Jul. 30, 2018	Jun. 28, 2017 shares	Apr. 30, 2017 EUR (€)	Jul. 31, 2015 USD ($) $ / shares shares	Sep. 30, 2021 USD ($) $ / shares	Sep. 30, 2020 USD ($) shares	Jun. 30, 2020 shares	Mar. 31, 2020 shares	Sep. 30, 2021 USD ($) $ / shares	Sep. 30, 2021 EUR (€)	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2016 EUR (€)	Sep. 30, 2021 EUR (€)	Jul. 10, 2020 USD ($)	Jul. 09, 2020 EUR (€)	Apr. 22, 2020 USD ($)	Jun. 30, 2018 EUR (€)
Common Stock And Note Purchase Agreement [Line Items]
Proceeds from issuance of common stock, net of issuance costs																	$ 14,982,663
Common stock, par value | $ / shares											$ 0.01				$ 0.01			$ 0.01
Common Stock [Member]
Common Stock And Note Purchase Agreement [Line Items]
Stock issued during period, shares, new issues | shares												1,523,663	2,739,442	2,814,934
EIB [Member]
Common Stock And Note Purchase Agreement [Line Items]
Fund drawn period																			36 months
Percentage of participation percentage interest						2.10%
Fair value of debt																					$ 15,800,000
Amount of outstanding borrowings															$ 25,408,938
Deferred interest payable											$ 4,566,738				$ 4,566,738
EIB [Member] | Euro [Member]
Common Stock And Note Purchase Agreement [Line Items]
Senior unsecured Loan | €																			€ 25,000,000
Amount of cumulative equity capital raised | €						€ 15,000,000
Amount of outstanding borrowings | €																€ 21,943,983
Deferred interest payable | €																				€ 3,943,983
EIB debt financing facility [Member]
Common Stock And Note Purchase Agreement [Line Items]
Defer total interest payments | €	€ 720,000
PPP [Member]
Common Stock And Note Purchase Agreement [Line Items]
Debt instrument, face amount																							$ 879,630
Percentage of interest accrues															1.00%	1.00%
Interest expense											1,222,867	$ 1,183,927			$ 3,586,018		$ 2,267,085
PPP [Member] | Subsidiary Note [Member]
Common Stock And Note Purchase Agreement [Line Items]
Debt instrument, face amount																							$ 259,353
MGHIF Financing Agreement [Member]
Common Stock And Note Purchase Agreement [Line Items]
Stock issued during period, shares, new issues | shares										2,273
Shares issued, price per share | $ / shares										$ 2,200
Proceeds from issuance of common stock, net of issuance costs										$ 5,000,000.0
Debt instrument, interest rate, stated percentage										8.00%
Debt instrument, face amount										$ 1,000,000.0
MGHIF Financing Agreement [Member] | Second Amended and Restated Senior Secured Promissory Note [Member]
Common Stock And Note Purchase Agreement [Line Items]
Accrued and unpaid interest		$ 285,512
Annual payments plus accrued and unpaid interest			$ 166,667
Beginning date of debt maturity			Jan. 02, 2019
MGHIF Financing Agreement [Member] | Second Amended and Restated Senior Secured Promissory Note [Member] | Private Placement [Member] | Common Stock [Member]
Common Stock And Note Purchase Agreement [Line Items]
Accrued and unpaid interest due date							Jul. 14, 2018
Amended and Restated MGHIF Financing Agreement [Member]
Common Stock And Note Purchase Agreement [Line Items]
Debt instrument, interest rate, stated percentage								10.00%
Debt instrument, extended maturity date								Jul. 14, 2018
Issuance of common stock warrants to purchase | shares								656
Assignment Agreement [Member] | Convertible Note [Member]
Common Stock And Note Purchase Agreement [Line Items]
Stock issued during period, shares, new issues | shares																		763,905
Proceeds from issuance of common stock, net of issuance costs																		$ 1,451,000
Common stock, par value | $ / shares					$ 0.01
Issuance of convertible notes | shares				450,000	500,000
Fair value of Convertible notes											$ 1,300,000				$ 1,300,000
Assignment Agreement [Member] | Convertible Note [Member] | Euro [Member]
Common Stock And Note Purchase Agreement [Line Items]
Unconverted Convertible Notes | €																				€ 1,300,000
First Tranche [Member] | EIB [Member]
Common Stock And Note Purchase Agreement [Line Items]
Debt instrument, interest rate, stated percentage									6.00%
First Tranche [Member] | EIB [Member] | Euro [Member]
Common Stock And Note Purchase Agreement [Line Items]
Senior unsecured Loan | €									€ 10,000,000
Interst rate									EURIBOR plus 4%
Second Tranche [Member] | EIB [Member] | Euro [Member]
Common Stock And Note Purchase Agreement [Line Items]
Senior unsecured Loan | €																								€ 3,000,000
Third Tranche [Member] | EIB [Member] | Euro [Member]
Common Stock And Note Purchase Agreement [Line Items]
Senior unsecured Loan | €						5,000,000
Four Tranche [Member] | EIB [Member] | Euro [Member]
Common Stock And Note Purchase Agreement [Line Items]
Senior unsecured Loan | €						€ 5,000,000
OpGen's equity value [Member] | EIB [Member]
Common Stock And Note Purchase Agreement [Line Items]
Percentage of participation percentage interest						0.30%
Five Tranche [Member] | EIB [Member] | Euro [Member]
Common Stock And Note Purchase Agreement [Line Items]
Senior unsecured Loan | €																						€ 5,000,000