Business and Basis of Presentation - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended				12 Months Ended	3 Months Ended	6 Months Ended		3 Months Ended	6 Months Ended	1 Months Ended		3 Months Ended		3 Months Ended			6 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 Segment	Jun. 30, 2012	Jun. 30, 2013 Minimum [Member]	Jun. 30, 2013 Maximum [Member]	Dec. 31, 2011 FUSILEV [Member]	Jun. 30, 2013 Rebates [Member]	Jun. 30, 2013 Rebates [Member]	Jun. 30, 2013 Reclassification out of Accumulated Other Comprehensive Income [Member]	Jun. 30, 2013 Mundipharma [Member]	Jun. 30, 2013 Mundipharma [Member]	Mar. 31, 2009 RIT Oncology, LLC [Member]	Dec. 31, 2008 RIT Oncology, LLC [Member]	Jun. 30, 2013 Accounts Payable and Accrued Liabilities [Member] Liabilities as part of business combination [Member]	Jun. 30, 2013 IPR&D - Captisol-enabled, propylene glycol-free melphalan rights [Member]	Jun. 30, 2013 In-process research and development [Member]	Jun. 30, 2013 Research and development and sales and marketing activities [Member]	Jun. 30, 2012 Research and development and sales and marketing activities [Member]	Jun. 30, 2013 Research and development and sales and marketing activities [Member]	Jun. 30, 2012 Research and development and sales and marketing activities [Member]	Jun. 30, 2013 Research and development and sales and marketing activities [Member] Accounts Payable and Accrued Liabilities [Member]	Jun. 30, 2013 As Restated [Member]	Jun. 30, 2013 ZEVALIN Rights [Member]	Jun. 30, 2013 Developed technology in process research and development [Member] Minimum [Member]	Jun. 30, 2013 Developed technology in process research and development [Member] Maximum [Member]	Jun. 30, 2013 Spectrum Pharma Canada [Member]
Related Party Transaction [Line Items]
Canadian affiliate owned																											50.00%
Fund made out of expenditure			100.00%
Number of reportable segment			1
Number of days customer allowed to return the product			30 days
Customer return the product before the expiration period			6 months
Increase in Medicaid rebate accrual								$ 1,000,000	$ 1,000,000
Increase in net loss, Medicaid rebate accrual								1,000,000	1,000,000	0
Percentage of rights acquired														50.00%
Remaining Percentage of rights acquired													50.00%
Amortized cost of goods sold estimated useful life					1 year	10 years	8 years 8 months 12 days																	10 years	10 years	15 years
Achievement of milestone capitalized							16,800,000
Achievement of milestone capitalized	7,700,000		7,700,000													7,700,000
Impairment loss	0	0	0	0							1,000,000	1,000,000
Understatement of intangible asset amortization																	2,100,000
Overstatement amount recorded in financial statement															1,000,000			6,700,000				7,700,000
Reduction of selling general and administrative and research and development expenses																		100,000	500,000	500,000	1,000,000
Accumulated deficit																							$ 7,200,000