Cover Page	9 Months Ended
	Sep. 30, 2019 shares
Cover page.
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Entity File Number	000-22339
Entity Registrant Name	RAMBUS INC
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	94-3112828
Entity Address, Address Line One	1050 Enterprise Way
Entity Address, Address Line Two	Suite 700
Entity Address, City or Town	Sunnyvale
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94089
City Area Code	408
Local Phone Number	462-8000
Title of 12(b) Security	Common Stock, $.001 Par Value
Trading Symbol	RMBS
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding	111,493,448
Entity Central Index Key	0000917273
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Amendment Flag	false