Fair Value Measurements - Summary of Asset and Liability Fair Values (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Assets:
Mutual funds	$ 3,062	$ 3,062
Total Assets	85,537us-gaap_AssetsFairValueDisclosure	84,400us-gaap_AssetsFairValueDisclosure
Liabilities:
Deferred executive compensation liability	5,593	4,694
Deferred development costs	15,119
Deferred development costs		15,785
Ligand Contingent Consideration	5,091	4,901
Talon CVR	2,689	2,379
Corixa Liability	62	62
Total Liabilities	28,554us-gaap_LiabilitiesFairValueDisclosure	27,821us-gaap_LiabilitiesFairValueDisclosure
Bank CDs [Member]
Assets:
Marketable securities, fair value	246	244
Money market funds [Member]
Assets:
Marketable securities, fair value	66,970	66,945
Equity securities and secured promissory note [Member]
Assets:
Marketable securities, fair value	7,944	7,191
Secured promissory note [Member]
Assets:
Marketable securities, fair value	0	0
Deferred compensation investments, including life insurance cash surrender value [Member]
Assets:
Marketable securities, fair value	7,315	6,958
Level 1 [Member]
Assets:
Total Assets	7,944	7,191
Level 1 [Member] \| Equity securities and secured promissory note [Member]
Assets:
Marketable securities, fair value	7,944	7,191
Level 2 [Member]
Assets:
Mutual funds	3,062	3,062
Total Assets	77,593	77,209
Liabilities:
Deferred executive compensation liability	5,593	4,694
Total Liabilities	5,593	4,694
Level 2 [Member] \| Bank CDs [Member]
Assets:
Marketable securities, fair value	246	244
Level 2 [Member] \| Money market funds [Member]
Assets:
Marketable securities, fair value	66,970	66,945
Level 2 [Member] \| Deferred compensation investments, including life insurance cash surrender value [Member]
Assets:
Marketable securities, fair value	7,315	6,958
Level 3 [Member]
Assets:
Total Assets	0	0
Liabilities:
Deferred development costs	15,119
Deferred development costs		15,785
Ligand Contingent Consideration	5,091	4,901
Talon CVR	2,689	2,379
Corixa Liability	62	62
Total Liabilities	22,961	23,127
Level 3 [Member] \| Secured promissory note [Member]
Assets:
Marketable securities, fair value	$ 0	$ 0

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Fair value of financial and nonfinancial obligations.

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