Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) $ in Thousands	1 Months Ended	3 Months Ended	6 Months Ended
	Jan. 31, 2010 contingent_value_right	Jun. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of CVR Series | contingent_value_right	4
Transferred over Time | Phase 3 clinical trial
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gross contract asset		$ 10,000	$ 10,000
Maximum | Transferred over Time | Development, regulatory, & commercial milestones and tiered royalties
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments		375,000	375,000
Metabasis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of CVRs issued per acquiree share | contingent_value_right	4
Number of CVRs issued from each CVR series | contingent_value_right	1
Frequency of cash payments to CVR holders	6 months
Mark-to-market adjustment of CVR liability		700	100
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment in Viking common stock		36,140	36,140	$ 63,122
Total assets		190,596	190,596	166,864
Amounts owed to former licensor		0	0	44
Total liabilities		3,572	3,572	3,557
Recurring | Short-term investments, excluding Viking
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value		154,456	154,456	103,742
Recurring | Contingent liabilities | CyDex
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent liabilities		85	85	84
Recurring | Contingent liabilities | Metabasis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent liabilities		3,487	3,487	3,429
Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment in Viking common stock				63,122
Total assets		45,379	45,379	67,114
Amounts owed to former licensor		0	0	44
Total liabilities		0	0	44
Recurring | Level 1 | Short-term investments, excluding Viking
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value		9,239	9,239	3,992
Recurring | Level 1 | Contingent liabilities | CyDex
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent liabilities		0	0	0
Recurring | Level 1 | Contingent liabilities | Metabasis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent liabilities		0	0	0
Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment in Viking common stock		0	0	0
Total assets		144,939	144,939	99,615
Amounts owed to former licensor		0	0	0
Total liabilities		3,487	3,487	3,429
Recurring | Level 2 | Short-term investments, excluding Viking
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value		144,939	144,939	99,615
Recurring | Level 2 | Contingent liabilities | CyDex
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent liabilities		0	0	0
Recurring | Level 2 | Contingent liabilities | Metabasis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent liabilities		3,487	3,487	3,429
Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment in Viking common stock		0	0	0
Total assets		278	278	135
Amounts owed to former licensor		0	0	0
Total liabilities		85	85	84
Recurring | Level 3 | Short-term investments, excluding Viking
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, fair value		278	278	135
Recurring | Level 3 | Contingent liabilities | CyDex
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent liabilities		85	85	84
Recurring | Level 3 | Contingent liabilities | Metabasis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent liabilities		$ 0	$ 0	$ 0