Pieris Pharmaceuticals, Inc. Quarterly report pursuant to Section 13 or 15(d)

Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity - Narrative (Details)

Stockholders' Equity - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions				1 Months Ended		3 Months Ended	9 Months Ended	38 Months Ended
	Jun. 25, 2021	May 20, 2021	Apr. 01, 2020	Aug. 31, 2021	Aug. 31, 2018	Sep. 30, 2021	Sep. 30, 2021	Sep. 30, 2021	Dec. 31, 2020	Apr. 30, 2020	Nov. 30, 2019	Jan. 31, 2019	Jun. 30, 2016
Class of Stock [Line Items]
Common stock, shares authorized (in shares)						300,000,000	300,000,000	300,000,000	300,000,000
Common stock, shares issued (in shares)						71,504,630	71,504,630	71,504,630	56,002,815
Common stock, shares outstanding (in shares)						71,504,630	71,504,630	71,504,630	56,002,815
Par value of common stock (USD per share)						$ 0.001	$ 0.001	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)						10,000,000	10,000,000	10,000,000	10,000,000
Preferred stock, shares issued (in shares)						15,617	15,617	15,617	14,429
Preferred stock, shares outstanding (in shares)						15,617	15,617	15,617	14,429
Par value of preferred stock (USD per share)						$ 0.001	$ 0.001	$ 0.001	$ 0.001
Jefferies LLC
Class of Stock [Line Items]
Par value of common stock (USD per share)				$ 0.001
At the market offering
Class of Stock [Line Items]
Sale of stock, authorized amount					$ 50.0
Shares of stock sold, net consideration								$ 23.2
At the market offering \| Jefferies LLC
Class of Stock [Line Items]
Sale of stock, authorized amount				$ 50.0
At the market offering 1 \| Jefferies LLC
Class of Stock [Line Items]
Shares of stock sold (in shares)						4,600,000
Shares of stock sold, net consideration						$ 24.0
Shares of stock sold, price (USD per share)						$ 5.27	$ 5.27	$ 5.27
At the market offering 2 \| Jefferies LLC
Class of Stock [Line Items]
Shares of stock sold (in shares)							7,600,000
Shares of stock sold, net consideration							$ 36.7
Shares of stock sold, price (USD per share)						$ 4.86	$ 4.86	$ 4.86
Common Stock \| Biotechnology Value Fund, L.P.
Class of Stock [Line Items]
Shares of stock sold (in shares)			3,000,000
Common Stock \| Stock exchange, shares from existing shareholders
Class of Stock [Line Items]
Shares of stock sold (in shares)		5,000,000
2020 Plan
Class of Stock [Line Items]
Shares of stock authorized pursuant to the 2020 Plan (in shares)						3,500,000	3,500,000	3,500,000
Additional shares authorized (in shares)	2,250,000
2019 Plan
Class of Stock [Line Items]
Shares of stock terminated under the 2019 Plan (in shares)							1,579,678
Series A Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)						85	85	85	2,907
Preferred stock, shares outstanding (in shares)						85	85	85	2,907
Series A Preferred Stock \| Preferred Stock \| Stock exchange, shares from existing shareholders
Class of Stock [Line Items]
Par value of preferred stock (USD per share)													$ 0.001
Series B Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)						4,026	4,026	4,026	5,000
Preferred stock, shares outstanding (in shares)						4,026	4,026	4,026	5,000
Series B Preferred Stock \| Preferred Stock \| Stock exchange, shares from existing shareholders
Class of Stock [Line Items]
Par value of preferred stock (USD per share)												$ 0.001
Series C Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)						3,506	3,506	3,506	3,522
Preferred stock, shares outstanding (in shares)						3,506	3,506	3,506	3,522
Series C Preferred Stock \| Preferred Stock \| Stock exchange, shares from existing shareholders
Class of Stock [Line Items]
Par value of preferred stock (USD per share)											$ 0.001
Series D Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)						3,000	3,000	3,000	3,000
Preferred stock, shares outstanding (in shares)						3,000	3,000	3,000	3,000
Series D Preferred Stock \| Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)			3,000
Shares of stock sold (in shares)			3,000
Series E Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)						5,000	5,000	5,000	0
Preferred stock, shares outstanding (in shares)						5,000	5,000	5,000	0
Series E Preferred Stock \| Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)		5,000
Par value of preferred stock (USD per share)		$ 0.001
Stock issued upon conversion (in shares)		1,000
Common stock ownership limit (as a percent)		9.99%
Beneficial ownership limitation (as a percent)		19.99%
Notice period before increase of beneficial ownership limitation		61 days
Series E Preferred Stock \| Preferred Stock \| Stock exchange, shares from existing shareholders
Class of Stock [Line Items]
Par value of preferred stock (USD per share)										$ 0.001
Series E Preferred Stock \| Preferred Stock \| Preferred share exchange
Class of Stock [Line Items]
Shares of stock sold (in shares)		5,000