Accrued Expenses - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 10, 2015
Securities Class Action Complaints [Member]
Other Accrued Liabilities [Line Items]
Proceeds from insurance settlement			$ 29,571
Disbursements of accrued claims and settlements	$ 23,500
Securities Class Action Complaints [Member] | Accrued Expense [Member]
Other Accrued Liabilities [Line Items]
Accrued claim settlement					$ 23,500	$ 23,500
Voluntary Resignation Program [Member]
Other Accrued Liabilities [Line Items]
Unpaid other termination benefits under the voluntary resignation program, current				$ 1,392
Aggregate other termination benefits expense under the voluntary resignation program		$ 4,241