Inventories - Narratives (Details)	9 Months Ended	12 Months Ended
Sep. 30, 2015	Dec. 31, 2017
Inventory Disclosure [Abstract]
Age of consignment inventory purchased by contract manufacturer		365 days
Age of consignment inventory purchased as a result of forecasted demand	180 days

Age of consignment inventory purchased as a result of forecasted demand, after this age inventory must be purchased by the Company if there is no forecasted demand.

No definition available.

Name:	rsys_Ageofconsignmentinventorypurchasedasaresultofforecasteddemand
Namespace Prefix:	rsys_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration