Mundipharma Agreement - Schedule of Drug Development Liability Adjustments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Accrued Drug Development Expenses [Roll Forward]
Balance at December 31, 2014		$ 1,141
Balance at March 31, 2015	1,141	1,141
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	(666)
Balance at March 31, 2015	15,119
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	666
(Less): Expenses incurred in 2015	(666)
Balance at March 31, 2015	1,141
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	(666)
(Less): Expenses incurred in 2015	0
Balance at March 31, 2015	$ 13,978