Borrowings - 2022 Notes - Additional Information (Detail) - USD ($)		12 Months Ended
	Dec. 22, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule Of Debt Instruments [Line Items]
Debt issuance costs			$ 100,000
Debt maturity date		Jul. 15, 2020
Interest expense		$ 19,232,000	18,230,000	$ 10,938,000
Change of Control Event [Member]
Schedule Of Debt Instruments [Line Items]
Redemption price as percentage of principal amount of notes plus accrued and unpaid interest	101.00%
Asset Sale Event [Member]
Schedule Of Debt Instruments [Line Items]
Redemption price as percentage of principal amount of notes plus accrued and unpaid interest	100.00%
Hercules [Member]
Schedule Of Debt Instruments [Line Items]
Interest expense		$ 5,400,000	$ 4,700,000	$ 4,900,000
2022 Notes [Member]
Schedule Of Debt Instruments [Line Items]
Aggregate principal amount of loan	$ 175,000,000
Net proceeds from the debt issuance	$ 168,500,000
Interest rate (as a percent)	11.50%
Debt issuance costs	$ 900,000
Semi-annual installments of principal	$ 21,875,000
Debt maturity date	Dec. 15, 2022
Effective interest rate		12.32%
Interest expense		$ 500,000
2022 Notes [Member] | Conversion Terms, Fundamental Changes [Member]
Schedule Of Debt Instruments [Line Items]
Redemption price as percentage of principal amount of notes plus accrued and unpaid interest		100.00%
2022 Notes [Member] | Hercules [Member]
Schedule Of Debt Instruments [Line Items]
Aggregate principal amount of loan		$ 40,000,000