v3.22.4
Document And Entity Information - USD ($)
 12 Months Ended
Dec. 31, 2022
Feb. 17, 2023
Jun. 30, 2022
Document Information [Line Items]      
Entity Central Index Key 0001280452    
Entity Registrant Name MONOLITHIC POWER SYSTEMS INC    
Amendment Flag false    
Current Fiscal Year End Date --12-31    
Document Fiscal Period Focus FY    
Document Fiscal Year Focus 2022    
Document Type 10-K    
Document Annual Report true    
Document Period End Date Dec. 31, 2022    
Document Transition Report false    
Entity File Number 000-51026    
Entity Incorporation, State or Country Code DE    
Entity Tax Identification Number 77-0466789    
Entity Address, Address Line One 5808 Lake Washington Blvd. NE    
Entity Address, City or Town Kirkland    
Entity Address, State or Province WA    
Entity Address, Postal Zip Code 98033    
City Area Code 425    
Local Phone Number 296-9956    
Title of 12(b) Security Common Stock, par value $0.001 per share    
Trading Symbol MPWR    
Security Exchange Name NASDAQ    
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Large Accelerated Filer    
Entity Small Business false    
Entity Emerging Growth Company false    
ICFR Auditor Attestation Flag true    
Entity Shell Company false    
Entity Public Float     $ 13,300,000,000
Entity Common Stock, Shares Outstanding   47,305,000  
Auditor Firm ID 42    
Auditor Name Ernst & Young LLP    
Auditor Location San Jose, California