Accounts Payable, Accrued Expenses and Other - Schedule of Accounts Payable, Accrued Expenses and Other (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Accounts Payable And Accrued Liabilities [Line Items]
Accounts payable	$ 8,298	$ 2,692
Accrued goods and services	5,467	8,233
Accrued clinical trial costs	10,382	8,776
Accrued drug purchase costs		480
Accrued payroll and related benefits	1,362	3,394
Accrued severance expenses	1,736	774
Accrued interest	1,261	2,100
Accrued dividends payable	19	19
Deferred tax incentives	1,402	1,402
Total accounts payable, accrued expenses and other	33,989	29,369
Silver Creek [Member]
Accounts Payable And Accrued Liabilities [Line Items]
Warrant liability	$ 4,062	$ 1,499