FOLOTYN License Agreement and Development Liability - Schedule of Drug Development Liability Adjustments (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)
Accrued Drug Development Expenses [Roll Forward]
Balance at December 31, 2016	$ 861
Balance at December 31, 2017	275
FOLOTYN [Member]
Accrued Drug Development Expenses [Roll Forward]
Balance at December 31, 2016	13,130
Transfer from long-term to current in 2017	0
(Less): Expenses incurred in 2017	(744)
Balance at December 31, 2017	12,386
FOLOTYN [Member] | FOLOTYN Development Liability, Current [Member]
Accrued Drug Development Expenses [Roll Forward]
Balance at December 31, 2016	861
Transfer from long-term to current in 2017	158
(Less): Expenses incurred in 2017	(744)
Balance at December 31, 2017	275
FOLOTYN [Member] | FOLOTYN Development Liability, Long Term [Member]
Accrued Drug Development Expenses [Roll Forward]
Balance at December 31, 2016	12,269
Transfer from long-term to current in 2017	(158)
(Less): Expenses incurred in 2017	0
Balance at December 31, 2017	$ 12,111