Fair Value Measurements - Summary of Asset and Liability Fair Values (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Assets:
Marketable securities, fair value	$ 45
Total Assets	97,608	$ 94,731
Liabilities:
Deferred executive compensation liability	7,117	6,458
Deferred drug development liability	14,510
Deferred drug development costs		14,686
Ligand Contingent Consideration	6,000	5,227
Talon CVR	1,646	1,377
Corixa Liability	62	62
Total Liabilities	29,335	27,810
Bank CDs [Member]
Assets:
Marketable securities, fair value	246	245
Money market currency funds [Member]
Assets:
Marketable securities, fair value	80,146	80,116
Equity securities [Member]
Assets:
Marketable securities, fair value	7,520	5,189
Notes Receivable [Member]
Assets:
Marketable securities, fair value	0
Deferred compensation investments, including life insurance cash surrender value [Member]
Assets:
Marketable securities, fair value	9,651	9,181
Level 1 [Member]
Assets:
Total Assets	7,520	5,189
Level 1 [Member] | Equity securities [Member]
Assets:
Marketable securities, fair value	7,520	5,189
Level 2 [Member]
Assets:
Marketable securities, fair value	45
Total Assets	90,088	89,542
Liabilities:
Deferred executive compensation liability	7,117	6,458
Total Liabilities	7,117	6,458
Level 2 [Member] | Bank CDs [Member]
Assets:
Marketable securities, fair value	246	245
Level 2 [Member] | Money market currency funds [Member]
Assets:
Marketable securities, fair value	80,146	80,116
Level 2 [Member] | Deferred compensation investments, including life insurance cash surrender value [Member]
Assets:
Marketable securities, fair value	9,651	9,181
Level 3 [Member]
Assets:
Total Assets	0	0
Liabilities:
Deferred drug development liability	14,510
Deferred drug development costs		14,686
Ligand Contingent Consideration	6,000	5,227
Talon CVR	1,646	1,377
Corixa Liability	62	62
Total Liabilities	22,218	$ 21,352
Level 3 [Member] | Notes Receivable [Member]
Assets:
Marketable securities, fair value	$ 0