Net Product Sales by Geographic Region, Product Line, and Gross Product Sales by Significant Customers - Summary of Customers Representing 10% or More of Gross Product Sales (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenue, Major Customer [Line Items]
Gross product sales	$ 215,136	$ 284,685	$ 224,301
Oncology Supply, a division of ASD Specialty Healthcare, Inc., and its affiliates (excluding ICS) [Member]
Revenue, Major Customer [Line Items]
Gross product sales	78,989	115,079	79,497
McKesson Corporation and its affiliates [Member]
Revenue, Major Customer [Line Items]
Gross product sales	73,577	93,656	44,350
Integrated Commercialization Solutions, Inc. (ICS) [Member]
Revenue, Major Customer [Line Items]
Gross product sales			35,548
Cardinal Health, Inc. and its affiliates [Member]
Revenue, Major Customer [Line Items]
Gross product sales	37,414
All Other Customers [Member]
Revenue, Major Customer [Line Items]
Gross product sales	$ 25,156	$ 75,950	$ 64,906
Customer Concentration Risk [Member] | Gross Product Sales [Member]
Revenue, Major Customer [Line Items]
Percentage of gross product sales	100.00%	100.00%	100.00%
Customer Concentration Risk [Member] | Gross Product Sales [Member] | Oncology Supply, a division of ASD Specialty Healthcare, Inc., and its affiliates (excluding ICS) [Member]
Revenue, Major Customer [Line Items]
Percentage of gross product sales	36.70%	40.40%	35.40%
Customer Concentration Risk [Member] | Gross Product Sales [Member] | McKesson Corporation and its affiliates [Member]
Revenue, Major Customer [Line Items]
Percentage of gross product sales	34.20%	32.90%	19.80%
Customer Concentration Risk [Member] | Gross Product Sales [Member] | Integrated Commercialization Solutions, Inc. (ICS) [Member]
Revenue, Major Customer [Line Items]
Percentage of gross product sales	0.00%	0.00%	15.80%
Customer Concentration Risk [Member] | Gross Product Sales [Member] | Cardinal Health, Inc. and its affiliates [Member]
Revenue, Major Customer [Line Items]
Percentage of gross product sales	17.40%	0.00%	0.00%
Customer Concentration Risk [Member] | Gross Product Sales [Member] | All Other Customers [Member]
Revenue, Major Customer [Line Items]
Percentage of gross product sales	11.70%	26.70%	29.00%
Customer Concentration Risk [Member] | Gross Product Sales [Member] | Maximum [Member] | Integrated Commercialization Solutions, Inc. (ICS) [Member]
Revenue, Major Customer [Line Items]
Percentage of gross product sales		10.00%
Customer Concentration Risk [Member] | Gross Product Sales [Member] | Maximum [Member] | Cardinal Health, Inc. and its affiliates [Member]
Revenue, Major Customer [Line Items]
Percentage of gross product sales	10.00%	10.00%