Mundipharma Agreement - Schedule of Drug Development Liability Adjustments (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2015 USD ($)
Accrued Drug Development Expenses [Roll Forward]
Balance at December 31, 2014	$ 1,141
Balance at June 30, 2015	573
FOLOTYN [Member]
Accrued Drug Development Expenses [Roll Forward]
Balance at December 31, 2014	15,785
Transfer from long-term to current in 2015	0
(Less): Expenses incurred in 2015	(1,296)
Balance at June 30, 2015	14,489
FOLOTYN [Member] | Drug Development Liability Current [Member]
Accrued Drug Development Expenses [Roll Forward]
Balance at December 31, 2014	1,141
Transfer from long-term to current in 2015	728
(Less): Expenses incurred in 2015	(1,296)
Balance at June 30, 2015	573
FOLOTYN [Member] | Drug Development Liability Long Term [Member]
Accrued Drug Development Expenses [Roll Forward]
Balance at December 31, 2014	14,644
Transfer from long-term to current in 2015	(728)
(Less): Expenses incurred in 2015	0
Balance at June 30, 2015	$ 13,916