Fair Value Measurement - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Contingent liabilities - Crystal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Payment for contingent consideration liabilities	$ 3,000	$ 1,800
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	998,324	656,665
Liabilities, fair value	9,017	12,741
Recurring | Contingent liabilities - Crystal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, fair value	2,659	6,477
Recurring | Contingent liabilities - CyDex
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, fair value	348	514
Recurring | Contingent liabilities - Metabasis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, fair value	5,935	5,551
Recurring | Liability for restricted investments owed to former licensees
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, fair value	75	199
Recurring | Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	939,989	601,217
Recurring | Investment in Viking common stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	48,425	46,191
Recurring | Investment in warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	9,910	9,257
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	61,408	56,774
Liabilities, fair value	75	199
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Contingent liabilities - Crystal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, fair value	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Contingent liabilities - CyDex
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, fair value	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Contingent liabilities - Metabasis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, fair value	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Liability for restricted investments owed to former licensees
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, fair value	75	199
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	3,073	1,326
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Investment in Viking common stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	48,425	46,191
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Investment in warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	9,910	9,257
Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	936,791	599,891
Liabilities, fair value	5,935	5,551
Recurring | Significant Other Observable Inputs (Level 2) | Contingent liabilities - Crystal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, fair value	0	0
Recurring | Significant Other Observable Inputs (Level 2) | Contingent liabilities - CyDex
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, fair value	0	0
Recurring | Significant Other Observable Inputs (Level 2) | Contingent liabilities - Metabasis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, fair value	5,935	5,551
Recurring | Significant Other Observable Inputs (Level 2) | Liability for restricted investments owed to former licensees
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, fair value	0	0
Recurring | Significant Other Observable Inputs (Level 2) | Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	936,791	599,891
Recurring | Significant Other Observable Inputs (Level 2) | Investment in Viking common stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	0	0
Recurring | Significant Other Observable Inputs (Level 2) | Investment in warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	0	0
Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	125	0
Liabilities, fair value	3,007	6,991
Recurring | Significant Unobservable Inputs (Level 3) | Contingent liabilities - Crystal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, fair value	2,659	6,477
Recurring | Significant Unobservable Inputs (Level 3) | Contingent liabilities - CyDex
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, fair value	348	514
Recurring | Significant Unobservable Inputs (Level 3) | Contingent liabilities - Metabasis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, fair value	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Liability for restricted investments owed to former licensees
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, fair value	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Short-term investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	125	0
Recurring | Significant Unobservable Inputs (Level 3) | Investment in Viking common stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Investment in warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	0	$ 0
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
Maximum | Transferred over Time | Development, Regulatory, & Commercial Milestones and Tiered Royalties
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gross contract asset	$ 375,000