Document And Entity Information - shares	3 Months Ended
	Mar. 31, 2019	May 13, 2019
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 Common Stock, Shares Outstanding (in shares)		28,519,259
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Amendment Flag	false