Document And Entity Information - shares	6 Months Ended
	Jun. 30, 2020	Aug. 11, 2020
Document Information [Line Items]
Entity Registrant Name	KEMPHARM, INC
Entity Central Index Key	0001434647
Trading Symbol	kmph
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Current Reporting Status	Yes
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Small Business	true
Entity Interactive Data Current	Yes
Entity Common Stock, Shares Outstanding (in shares)		72,463,841
Entity Shell Company	false
Document Type	10-Q
Document Period End Date	Jun. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Amendment Flag	false
Title of 12(b) Security	Common