Summary of Significant Accounting Policies and Use of Estimates (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Jan. 01, 2018
Accounting Policies [Line Items]
Increase (decrease) in retained earnings due to revenue recognition	$ (619,041)	$ (599,886)
FUSILEV, MARQIBO, and BELEODAQ [Member]
Accounting Policies [Line Items]
Number of months customers are allowed to return products	6 months
EVOMELA [Member]
Accounting Policies [Line Items]
Number of months customers are allowed to return products	12 months
Number of months prior to product expiration during which customer can return product	6 months
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Accounting Policies [Line Items]
Increase (decrease) in retained earnings due to revenue recognition			$ 4,700