Document and Entity Information	6 Months Ended
	Jun. 30, 2013	Aug. 05, 2013
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	true
Amendment Description	We are filing this Amendment No. 1 to our Quarterly Report on Form 10-Q for the period ended June 30, 2013 to amend and restate portions of our original Quarterly Report for this period (the “Original Report”). This Amendment No. 1 amends and restates the following items from the Original Report: (A) Part I, Item I - Financial Statements, (B) Part I, Item 2 - Management’s Discussion and Analysis of Financial Condition and Results of Operations, (C) Part I, Item 4 - Controls and Procedures, and (D) Part II, Item IA - Risk Factors. The disclosures set forth in these items in the Original Report, that are amended by this Amendment No. 1 include:
Document Period End Date	Jun. 30, 2013
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q2
Trading Symbol	SPPI
Entity Registrant Name	SPECTRUM PHARMACEUTICALS INC
Entity Central Index Key	0000831547
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		63,307,719