v3.23.1
Cover Page - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2022
Apr. 28, 2023
Jun. 30, 2022
Cover [Abstract]      
Document Type 10-K/A    
Document Annual Report true    
Document Period End Date Dec. 31, 2022    
Current Fiscal Year End Date --12-31    
Document Transition Report false    
Entity File Number 001-35006    
Entity Registrant Name SPECTRUM PHARMACEUTICALS, INC.    
Entity Incorporation, State or Country Code DE    
Entity Tax Identification Number 93-0979187    
Entity Address, Address Line One Pilot House - Lewis Wharf, 2 Atlantic Ave    
Entity Address, Address Line Two 6th Floor    
Entity Address, City or Town Boston    
Entity Address, State or Province MA    
Entity Address, Postal Zip Code 02110    
City Area Code 617    
Local Phone Number 586-3900    
Title of 12(b) Security Common Stock, $0.001 par value    
Trading Symbol SPPI    
Security Exchange Name NASDAQ    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Non-accelerated Filer    
Entity Small Business true    
Entity Emerging Growth Company false    
ICFR Auditor Attestation Flag false    
Entity Shell Company false    
Entity Public Float     $ 115.4
Entity Common Stock, Shares Outstanding   205,284,506  
Amendment Flag true    
Document Fiscal Year Focus 2022    
Document Fiscal Period Focus FY    
Entity Central Index Key 0000831547    
Amendment Description Spectrum Pharmaceuticals, Inc., (“we”, “us”, or the “Company”), is filing this Amendment No. 1 on Form 10-K/A, or Amendment No. 1, to its Annual Report on Form 10-K for the fiscal year ended December 31, 2022, which was filed with the Securities and Exchange Commission on March 31, 2023, or the Original Form 10-K, for the sole purpose of including the information required by Part III of Form 10-K. This information was previously omitted from the Original 10-K in reliance on General Instruction G(3) to Form 10-K, which permits the information in Part III to be incorporated in the Form 10-K by reference from the Company’s definitive proxy statement if such statement is filed no later than 120 days after the Company’s fiscal year-end. The Company is filing this Amendment No. 1 to include Part III information in its Form 10-K because it will not file a definitive proxy statement containing this information within 120 days after the end of the fiscal year covered by the Original Form 10-K. This Amendment No. 1 amends and restates in their entirety Items 10, 11, 12, 13 and 14 of Part III of the Original Form 10-K. Pursuant to Rule 12b-15 under the Securities Exchange Act of 1934, as amended, or the Exchange Act, this Amendment No. 1 also contains certifications pursuant to Section 302 of the Sarbanes-Oxley Act of 2002, which are attached hereto. Because no financial statements have been included in this Amendment No. 1 and this Amendment No. 1 does not contain or amend any disclosure with respect to Items 307 and 308 of Regulation S-K, paragraphs 3, 4, and 5 of the certifications have been omitted. Except as explicitly set forth herein, this Amendment No. 1 does not purport to modify or update the disclosures in, or exhibits to, the Original Form 10-K or to update the Original Form 10-K to reflect events occurring after the date of such filing.    
Auditor Name RSM US LLP    
Auditor Firm ID 49    
Auditor Location Los Angeles, California