Benefit Plans	12 Months Ended
	Dec. 31, 2020
Retirement Benefits [Abstract]
Benefit Plans	Benefit PlansRambus has a 401(k) Plan (the “401(k) Plan”) qualified under Section 401(k) of the Internal Revenue Code of 1986. Each eligible employee may elect to contribute up to 60% of the employee’s annual compensation to the 401(k) Plan, up to the Internal Revenue Service limit. Rambus, at the discretion of its Board of Directors, may match employee contributions to the 401(k) Plan. The Company matches 50% of eligible employee’s contribution, up to the first 6% of an eligible employee’s qualified earnings. For the years ended December 31, 2020, 2019 and 2018, Rambus made matching contributions totaling approximately $1.8 million, $2.0 million and $2.1 million, respectively.