Long-term Debt - Additional Information (Detail)			3 Months Ended		9 Months Ended
	Jul. 28, 2015 USD ($) Tranche	Jun. 17, 2014 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Debt Instrument [Line Items]
Net proceeds from issuance of convertible notes						$ 192,921,000
PDL BioPharma
Debt Instrument [Line Items]
Proceeds from collaborators	$ 50,000,000				$ 313,000
Number of tranches | Tranche	2
Future Maximum Royalty Payments Receivable in 2015			$ 20,000,000		$ 20,000,000
Royalty rate in 2015			2.50%		2.50%
Future Maximum Royalty Payments Receivable in 2016			$ 20,000,000		$ 20,000,000
Royalty rate in 2016			5.00%		5.00%
Royalty rate in 2019			6.50%		6.50%
Future Maximum Royalty Payments Receivable in 2017			$ 20,000,000		$ 20,000,000
Internal rate of return					10.00%
Royalty rate in 2017			5.00%		5.00%
Future Maximum Royalty Payments Receivable in 2018			$ 20,000,000		$ 20,000,000
Royalty rate in 2018			5.00%		5.00%
Royalty rate in year five			5.00%		5.00%
Interest expense, debt					$ 1,300,000
PDL BioPharma | Put And Call Options
Debt Instrument [Line Items]
Internal rate of return	10.00%
PDL BioPharma | Put And Call Options | If exercised on or prior to the first anniversary of the closing date
Debt Instrument [Line Items]
Put and call options exercise price as percentage of amount paid			115.00%		115.00%
PDL BioPharma | Put And Call Options | If exercised after the first anniversary but on or prior to the second anniversary of the closing date
Debt Instrument [Line Items]
Put and call options exercise price as percentage of amount paid			120.00%		120.00%
PDL BioPharma | Put And Call Options | If exercised after the second anniversary of the closing date
Debt Instrument [Line Items]
Put and call options exercise price as percentage of amount paid			130.00%		130.00%
PDL BioPharma | Maximum
Debt Instrument [Line Items]
Royalty Commitments, amount			$ 150,000,000		$ 150,000,000
PDL BioPharma | To be received one year from the effective date
Debt Instrument [Line Items]
Franchise Revenue	$ 50,000,000
PDL BioPharma | To be received in two tranches between the six-month and twelve-month anniversary dates of the agreement
Debt Instrument [Line Items]
Franchise Revenue	$ 100,000,000
PDL BioPharma | Royalty rate for the remainder of the agreement if the Company draws down in excess of $150 million | Maximum
Debt Instrument [Line Items]
Royalty rate for excess withdrawal					7.50%
Senior Notes
Debt Instrument [Line Items]
Debt instrument, principal amount		$ 200,000,000	200,000,000		$ 200,000,000		$ 200,000,000
Net proceeds from issuance of convertible notes		192,900,000
Fees related to debt		6,000,000
Cost and expense related to debt		1,100,000
Expected life of debt					5 years
Interest expense, debt			$ 3,907,000	$ 3,717,000	$ 11,575,000	$ 4,253,000
Senior Notes | Convertible Note Hedge
Debt Instrument [Line Items]
Net proceeds from issuance of convertible notes		$ 43,200,000
Senior Notes | Liability Component
Debt Instrument [Line Items]
Debt instruments, effective interest rate			9.625%		9.625%