Fair Value Measurements - Summary of Asset and Liability Fair Values (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Assets:
Deferred compensation investments (life insurance cash surrender value)	$ 11,863	$ 9,181
Total Assets	158,006	94,731
Liabilities:
Deferred executive compensation liability (Note 17(f))	8,352	6,458
Drug development liability (Note 16)	13,130	14,686
Ligand Contingent Consideration (Note 10 (b))	0	5,227
Talon CVR (Note 10 (a))	1,253	1,377
Corixa Liability	62	62
Financial and Nonfinancial Liabilities, Fair Value Disclosure	22,797	27,810
Bank CDs [Member]
Assets:
Marketable securities, fair value	5,991	245
Money Market Funds [Member]
Assets:
Marketable securities, fair value	128,563	80,116
Equity Securities [Member]
Assets:
Marketable securities, fair value	11,533	5,189
Mutual Funds [Member]
Assets:
Marketable securities, fair value	56
Level 1 [Member]
Assets:
Total Assets	11,533	5,189
Level 1 [Member] | Equity Securities [Member]
Assets:
Marketable securities, fair value	11,533	5,189
Level 2 [Member]
Assets:
Deferred compensation investments (life insurance cash surrender value)	11,863	9,181
Total Assets	146,473	89,542
Liabilities:
Deferred executive compensation liability (Note 17(f))	8,352	6,458
Financial and Nonfinancial Liabilities, Fair Value Disclosure	8,352	6,458
Level 2 [Member] | Bank CDs [Member]
Assets:
Marketable securities, fair value	5,991	245
Level 2 [Member] | Money Market Funds [Member]
Assets:
Marketable securities, fair value	128,563	80,116
Level 2 [Member] | Mutual Funds [Member]
Assets:
Marketable securities, fair value	56
Level 3 [Member]
Liabilities:
Drug development liability (Note 16)	13,130	14,686
Ligand Contingent Consideration (Note 10 (b))	0	5,227
Talon CVR (Note 10 (a))	1,253	1,377
Corixa Liability	62	62
Financial and Nonfinancial Liabilities, Fair Value Disclosure	$ 14,445	$ 21,352