Accounts Payable, Accrued Expenses and Other - Schedule of Accounts Payable, Accrued Expenses and Other (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Accounts Payable And Accrued Liabilities [Line Items]
Accounts payable	$ 8,835	$ 2,692
Accrued goods and services	4,688	8,233
Accrued clinical trial costs	3,845	8,776
Accrued drug purchase costs	950	480
Accrued payroll and related benefits	2,500	3,394
Accrued severance expenses	1,166	774
Accrued interest	578	2,100
Accrued dividends payable	19	19
Deferred tax incentives	1,402	1,402
Total accounts payable, accrued expenses and other	$ 23,983	29,369
Silver Creek [Member]
Accounts Payable And Accrued Liabilities [Line Items]
Warrant liability		$ 1,499